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d221dd5f |
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03-Mar-2024 |
Byungchul Park <byungchul@sk.com> |
mm, vmscan: retry kswapd's priority loop with cache_trim_mode off on failure With cache_trim_mode on, reclaim logic doesn't bother reclaiming anon pages. However, it should be more careful to use the mode because it's going to prevent anon pages from being reclaimed even if there are a huge number of anon pages that are cold and should be reclaimed. Even worse, that leads kswapd_failures to reach MAX_RECLAIM_RETRIES and stopping kswapd from functioning until direct reclaim eventually works to resume kswapd. So kswapd needs to retry its scan priority loop with cache_trim_mode off again if the mode doesn't work for reclaim. The problematic behavior can be reproduced by: CONFIG_NUMA_BALANCING enabled sysctl_numa_balancing_mode set to NUMA_BALANCING_MEMORY_TIERING numa node0 (8GB local memory, 16 CPUs) numa node1 (8GB slow tier memory, no CPUs) Sequence: 1) echo 3 > /proc/sys/vm/drop_caches 2) To emulate the system with full of cold memory in local DRAM, run the following dummy program and never touch the region: mmap(0, 8 * 1024 * 1024 * 1024, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_POPULATE, -1, 0); 3) Run any memory intensive work e.g. XSBench. 4) Check if numa balancing is working e.i. promotion/demotion. 5) Iterate 1) ~ 4) until numa balancing stops. With this, you could see that promotion/demotion are not working because kswapd has stopped due to ->kswapd_failures >= MAX_RECLAIM_RETRIES. Interesting vmstat delta's differences between before and after are like: +-----------------------+-------------------------------+ | interesting vmstat | before | after | +-----------------------+-------------------------------+ | nr_inactive_anon | 321935 | 1664772 | | nr_active_anon | 1780700 | 437834 | | nr_inactive_file | 30425 | 40882 | | nr_active_file | 14961 | 3012 | | pgpromote_success | 356 | 1293122 | | pgpromote_candidate | 21953245 | 1824148 | | pgactivate | 1844523 | 3311907 | | pgdeactivate | 50634 | 1554069 | | pgfault | 31100294 | 6518806 | | pgdemote_kswapd | 30856 | 2230821 | | pgscan_kswapd | 1861981 | 7667629 | | pgscan_anon | 1822930 | 7610583 | | pgscan_file | 39051 | 57046 | | pgsteal_anon | 386 | 2192033 | | pgsteal_file | 30470 | 38788 | | pageoutrun | 30 | 412 | | numa_hint_faults | 27418279 | 2875955 | | numa_pages_migrated | 356 | 1293122 | +-----------------------+-------------------------------+ Link: https://lkml.kernel.org/r/20240304082118.20499-1-byungchul@sk.com Signed-off-by: Byungchul Park <byungchul@sk.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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47932e70 |
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11-Mar-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: remove folio from deferred split list before uncharging it When freeing a large folio, we must remove it from the deferred split list before we uncharge it as each memcg has its own deferred split list (with associated lock) and removing a folio from the deferred split list while holding the wrong lock will corrupt that list and cause various related problems. Link: https://lore.kernel.org/linux-mm/367a14f7-340e-4b29-90ae-bc3fcefdd5f4@arm.com/ Link: https://lkml.kernel.org/r/20240311191835.312162-1-willy@infradead.org Fixes: f77171d241e3 (mm: allow non-hugetlb large folios to be batch processed) Fixes: 29f3843026cf (mm: free folios directly in move_folios_to_lru()) Fixes: bc2ff4cbc329 (mm: free folios in a batch in shrink_folio_list()) Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Debugged-by: Ryan Roberts <ryan.roberts@arm.com> Tested-by: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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29f38430 |
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27-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: free folios directly in move_folios_to_lru() The few folios which can't be moved to the LRU list (because their refcount dropped to zero) used to be returned to the caller to dispose of. Make this simpler to call by freeing the folios directly through free_unref_folios(). Link: https://lkml.kernel.org/r/20240227174254.710559-13-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bc2ff4cb |
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27-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: free folios in a batch in shrink_folio_list() Use free_unref_page_batch() to free the folios. This may increase the number of IPIs from calling try_to_unmap_flush() more often, but that's going to be very workload-dependent. It may even reduce the number of IPIs as we now batch-free large folios instead of freeing them one at a time. Link: https://lkml.kernel.org/r/20240227174254.710559-12-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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2864f3d0 |
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25-Feb-2024 |
Barry Song <v-songbaohua@oppo.com> |
mm: madvise: pageout: ignore references rather than clearing young While doing MADV_PAGEOUT, the current code will clear PTE young so that vmscan won't read young flags to allow the reclamation of madvised folios to go ahead. It seems we can do it by directly ignoring references, thus we can remove tlb flush in madvise and rmap overhead in vmscan. Regarding the side effect, in the original code, if a parallel thread runs side by side to access the madvised memory with the thread doing madvise, folios will get a chance to be re-activated by vmscan (though the time gap is actually quite small since checking PTEs is done immediately after clearing PTEs young). But with this patch, they will still be reclaimed. But this behaviour doing PAGEOUT and doing access at the same time is quite silly like DoS. So probably, we don't need to care. Or ignoring the new access during the quite small time gap is even better. For DAMON's DAMOS_PAGEOUT based on physical address region, we still keep its behaviour as is since a physical address might be mapped by multiple processes. MADV_PAGEOUT based on virtual address is actually much more aggressive on reclamation. To untouch paddr's DAMOS_PAGEOUT, we simply pass ignore_references as false in reclaim_pages(). A microbench as below has shown 6% decrement on the latency of MADV_PAGEOUT, #define PGSIZE 4096 main() { int i; #define SIZE 512*1024*1024 volatile long *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); for (i = 0; i < SIZE/sizeof(long); i += PGSIZE / sizeof(long)) p[i] = 0x11; madvise(p, SIZE, MADV_PAGEOUT); } w/o patch w/ patch root@10:~# time ./a.out root@10:~# time ./a.out real 0m49.634s real 0m46.334s user 0m0.637s user 0m0.648s sys 0m47.434s sys 0m44.265s Link: https://lkml.kernel.org/r/20240226005739.24350-1-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: SeongJae Park <sj@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4acef569 |
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13-Feb-2024 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: improve swappiness handling The reclaimable number of anon pages used to set initial reclaim priority is only based on get_swappiness(). Use can_reclaim_anon_pages() to include NUMA node demotion. Also move the swappiness handling of when !__GFP_IO in try_to_shrink_lruvec() into isolate_folios(). Link: https://lkml.kernel.org/r/20240214060538.3524462-6-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Donet Tom <donettom@linux.vnet.ibm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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cc25bbe1 |
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13-Feb-2024 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: improve struct lru_gen_mm_walk Rename max_seq to seq in struct lru_gen_mm_walk to keep consistent with struct lru_gen_mm_state. Note that seq is not always up to date with max_seq from lru_gen_folio. No functional changes. Link: https://lkml.kernel.org/r/20240214060538.3524462-5-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Donet Tom <donettom@linux.vnet.ibm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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2d823764 |
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13-Feb-2024 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: improve reset_mm_stats() struct lruvec* is already a field of struct lru_gen_mm_walk. Remove the parameter struct lruvec* into functions that already have access to struct lru_gen_mm_walk*. Also, we do not need to handle reset histogram stats when !should_walk_mmu(). Remove the call to reset_mm_stats() in iterate_mm_list_nowalk(). Link: https://lkml.kernel.org/r/20240214060538.3524462-4-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Donet Tom <donettom@linux.vnet.ibm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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51973cc9 |
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13-Feb-2024 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: improve should_run_aging() scan_control *sc does not need to be passed into should_run_aging(), as it provides only the reclaim priority. This can be moved to get_nr_to_scan(). Refactor should_run_aging() and get_nr_to_scan() to improve code readability. No functional changes. Link: https://lkml.kernel.org/r/20240214060538.3524462-3-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Donet Tom <donettom@linux.vnet.ibm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1ce2292c |
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13-Feb-2024 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: drop unused parameter Patch series "mm/mglru: code cleanup and refactoring" This provides MGLRU code cleanup and refactoring for better readability. This patch (of 5): struct scan_control *sc is currently passed into try_to_inc_max_seq() and run_aging(). This parameter is not used. Drop the unused parameter struct scan_control *sc. No functional change. Link: https://lkml.kernel.org/r/20240214060538.3524462-1-kinseyho@google.com Link: https://lkml.kernel.org/r/20240214060538.3524462-2-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Donet Tom <donettom@linux.vnet.ibm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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98141718 |
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04-Feb-2024 |
Hao Ge <gehao@kylinos.cn> |
mm/vmscan: make too_many_isolated return bool too_many_isolated() should return bool as does the similar too_many_isolated() in mm/compaction.c. Link: https://lkml.kernel.org/r/20240205042618.108140-1-gehao@kylinos.cn Signed-off-by: Hao Ge <gehao@kylinos.cn> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e321d7c9 |
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31-Jan-2024 |
Hao Ge <gehao@kylinos.cn> |
mm/vmscan: change the type of file from int to bool Change the type of file from int to bool because is_file_lru return bool Link: https://lkml.kernel.org/r/20240131103802.122920-1-gehao@kylinos.cn Signed-off-by: Hao Ge <gehao@kylinos.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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96200c91 |
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26-Jan-2024 |
Levi Yun <ppbuk5246@gmail.com> |
kswapd: replace try_to_freeze() with kthread_freezable_should_stop() Instead of using try_to_freeze, use kthread_freezable_should_stop in kswapd. By this, we can avoid unnecessary freezing when kswapd should stop. Link: https://lkml.kernel.org/r/20240126152556.58791-1-ppbuk5246@gmail.com Signed-off-by: Levi Yun <ppbuk5246@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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803de900 |
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20-Feb-2024 |
Vlastimil Babka <vbabka@suse.cz> |
mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sven van Ashbrook <svenva@chromium.org> Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBzPUVOZF%2Bg@mail.gmail.com/ Tested-by: Karthikeyan Ramasubramanian <kramasub@chromium.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Curtis Malainey <cujomalainey@chromium.org> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Takashi Iwai <tiwai@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5e0a760b |
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28-Dec-2023 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER commit 23baf831a32c ("mm, treewide: redefine MAX_ORDER sanely") has changed the definition of MAX_ORDER to be inclusive. This has caused issues with code that was not yet upstream and depended on the previous definition. To draw attention to the altered meaning of the define, rename MAX_ORDER to MAX_PAGE_ORDER. Link: https://lkml.kernel.org/r/20231228144704.14033-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b805ab3c |
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28-Dec-2023 |
Li Zhijian <lizhijian@fujitsu.com> |
mm/vmstat: move pgdemote_* out of CONFIG_NUMA_BALANCING Demotion can work well without CONFIG_NUMA_BALANCING. But the commit 23e9f0138963 ("mm/vmstat: move pgdemote_* to per-node stats") wrongly hid it behind CONFIG_NUMA_BALANCING. Fix it by moving them out of CONFIG_NUMA_BALANCING. Link: https://lkml.kernel.org/r/20231229022651.3229174-1-lizhijian@fujitsu.com Fixes: 23e9f0138963 ("mm/vmstat: move pgdemote_* to per-node stats") Signed-off-by: Li Zhijian <lizhijian@fujitsu.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7eb2d01a |
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27-Dec-2023 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: remove CONFIG_TRANSPARENT_HUGEPAGE Improve code readability by removing CONFIG_TRANSPARENT_HUGEPAGE, since the compiler should be able to automatically optimize out the code that promotes THPs during page table walks. No functional changes. Link: https://lkml.kernel.org/r/20231227141205.2200125-6-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Co-developed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Tested-by: Donet Tom <donettom@linux.vnet.ibm.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: kernel test robot <lkp@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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745b13e6 |
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27-Dec-2023 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: remove CONFIG_MEMCG Remove CONFIG_MEMCG in a refactoring to improve code readability at the cost of a few bytes in struct lru_gen_folio per node when CONFIG_MEMCG=n. Link: https://lkml.kernel.org/r/20231227141205.2200125-4-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Co-developed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Tested-by: Donet Tom <donettom@linux.vnet.ibm.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: kernel test robot <lkp@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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61dd3f24 |
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27-Dec-2023 |
Kinsey Ho <kinseyho@google.com> |
mm/mglru: add CONFIG_LRU_GEN_WALKS_MMU Add CONFIG_LRU_GEN_WALKS_MMU such that if disabled, the code that walks page tables to promote pages into the youngest generation will not be built. Also improves code readability by adding two helper functions get_mm_state() and get_next_mm(). Link: https://lkml.kernel.org/r/20231227141205.2200125-3-kinseyho@google.com Signed-off-by: Kinsey Ho <kinseyho@google.com> Co-developed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Tested-by: Donet Tom <donettom@linux.vnet.ibm.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: kernel test robot <lkp@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7d7ef0a4 |
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28-Nov-2023 |
Yosry Ahmed <yosryahmed@google.com> |
mm: memcg: restore subtree stats flushing Stats flushing for memcg currently follows the following rules: - Always flush the entire memcg hierarchy (i.e. flush the root). - Only one flusher is allowed at a time. If someone else tries to flush concurrently, they skip and return immediately. - A periodic flusher flushes all the stats every 2 seconds. The reason this approach is followed is because all flushes are serialized by a global rstat spinlock. On the memcg side, flushing is invoked from userspace reads as well as in-kernel flushers (e.g. reclaim, refault, etc). This approach aims to avoid serializing all flushers on the global lock, which can cause a significant performance hit under high concurrency. This approach has the following problems: - Occasionally a userspace read of the stats of a non-root cgroup will be too expensive as it has to flush the entire hierarchy [1]. - Sometimes the stats accuracy are compromised if there is an ongoing flush, and we skip and return before the subtree of interest is actually flushed, yielding stale stats (by up to 2s due to periodic flushing). This is more visible when reading stats from userspace, but can also affect in-kernel flushers. The latter problem is particulary a concern when userspace reads stats after an event occurs, but gets stats from before the event. Examples: - When memory usage / pressure spikes, a userspace OOM handler may look at the stats of different memcgs to select a victim based on various heuristics (e.g. how much private memory will be freed by killing this). Reading stale stats from before the usage spike in this case may cause a wrongful OOM kill. - A proactive reclaimer may read the stats after writing to memory.reclaim to measure the success of the reclaim operation. Stale stats from before reclaim may give a false negative. - Reading the stats of a parent and a child memcg may be inconsistent (child larger than parent), if the flush doesn't happen when the parent is read, but happens when the child is read. As for in-kernel flushers, they will occasionally get stale stats. No regressions are currently known from this, but if there are regressions, they would be very difficult to debug and link to the source of the problem. This patch aims to fix these problems by restoring subtree flushing, and removing the unified/coalesced flushing logic that skips flushing if there is an ongoing flush. This change would introduce a significant regression with global stats flushing thresholds. With per-memcg stats flushing thresholds, this seems to perform really well. The thresholds protect the underlying lock from unnecessary contention. This patch was tested in two ways to ensure the latency of flushing is up to par, on a machine with 384 cpus: - A synthetic test with 5000 concurrent workers in 500 cgroups doing allocations and reclaim, as well as 1000 readers for memory.stat (variation of [2]). No regressions were noticed in the total runtime. Note that significant regressions in this test are observed with global stats thresholds, but not with per-memcg thresholds. - A synthetic stress test for concurrently reading memcg stats while memory allocation/freeing workers are running in the background, provided by Wei Xu [3]. With 250k threads reading the stats every 100ms in 50k cgroups, 99.9% of reads take <= 50us. Less than 0.01% of reads take more than 1ms, and no reads take more than 100ms. [1] https://lore.kernel.org/lkml/CABWYdi0c6__rh-K7dcM_pkf9BJdTRtAU08M43KO9ME4-dsgfoQ@mail.gmail.com/ [2] https://lore.kernel.org/lkml/CAJD7tka13M-zVZTyQJYL1iUAYvuQ1fcHbCjcOBZcz6POYTV-4g@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CAAPL-u9D2b=iF5Lf_cRnKxUfkiEe0AMDTu6yhrUAzX0b6a6rDg@mail.gmail.com/ [akpm@linux-foundation.org: fix mm/zswap.c] [yosryahmed@google.com: remove stats flushing mutex] Link: https://lkml.kernel.org/r/CAJD7tkZgP3m-VVPn+fF_YuvXeQYK=tZZjJHj=dzD=CcSSpp2qg@mail.gmail.com Link: https://lkml.kernel.org/r/20231129032154.3710765-6-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Tested-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Chris Li <chrisl@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Ivan Babrou <ivan@cloudflare.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutny <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Tejun Heo <tj@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Wei Xu <weixugc@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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23e9f013 |
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02-Nov-2023 |
Li Zhijian <lizhijian@fujitsu.com> |
mm/vmstat: move pgdemote_* to per-node stats Demotion will migrate pages across nodes. Previously, only the global demotion statistics were accounted for. Changed them to per-node statistics, making it easier to observe where demotion occurs on each node. This will help to identify which nodes are under pressure. This patch also make pgdemote_* behind CONFIG_NUMA_BALANCING, since demotion is not available for !CONFIG_NUMA_BALANCING With this patch, here is a sample where node0 node1 are DRAM, node3 is PMEM: Global stats: $ grep demote /proc/vmstat pgdemote_kswapd 254288 pgdemote_direct 113497 pgdemote_khugepaged 0 Per-node stats: $ grep demote /sys/devices/system/node/node0/vmstat # demotion source pgdemote_kswapd 68454 pgdemote_direct 83431 pgdemote_khugepaged 0 $ grep demote /sys/devices/system/node/node1/vmstat # demotion source pgdemote_kswapd 185834 pgdemote_direct 30066 pgdemote_khugepaged 0 $ grep demote /sys/devices/system/node/node3/vmstat # demotion target pgdemote_kswapd 0 pgdemote_direct 0 pgdemote_khugepaged 0 Link: https://lkml.kernel.org/r/20231103031450.1456523-1-lizhijian@fujitsu.com Signed-off-by: Li Zhijian <lizhijian@fujitsu.com> Acked-by: "Huang, Ying" <ying.huang@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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c28ac3c7 |
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22-Dec-2023 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: skip special VMAs in lru_gen_look_around() Special VMAs like VM_PFNMAP can contain anon pages from COW. There isn't much profit in doing lookaround on them. Besides, they can trigger the pte_special() warning in get_pte_pfn(). Skip them in lru_gen_look_around(). Link: https://lkml.kernel.org/r/20231223045647.1566043-1-yuzhao@google.com Fixes: 018ee47f1489 ("mm: multi-gen LRU: exploit locality in rmap") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: syzbot+03fd9b3f71641f0ebf2d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/000000000000f9ff00060d14c256@google.com/ Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4376807b |
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07-Dec-2023 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: reclaim offlined memcgs harder In the effort to reduce zombie memcgs [1], it was discovered that the memcg LRU doesn't apply enough pressure on offlined memcgs. Specifically, instead of rotating them to the tail of the current generation (MEMCG_LRU_TAIL) for a second attempt, it moves them to the next generation (MEMCG_LRU_YOUNG) after the first attempt. Not applying enough pressure on offlined memcgs can cause them to build up, and this can be particularly harmful to memory-constrained systems. On Pixel 8 Pro, launching apps for 50 cycles: Before After Change Zombie memcgs 45 35 -22% [1] https://lore.kernel.org/CABdmKX2M6koq4Q0Cmp_-=wbP0Qa190HdEGGaHfxNS05gAkUtPA@mail.gmail.com/ Link: https://lkml.kernel.org/r/20231208061407.2125867-4-yuzhao@google.com Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: T.J. Mercier <tjmercier@google.com> Tested-by: T.J. Mercier <tjmercier@google.com> Cc: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com> Cc: Kairui Song <ryncsn@gmail.com> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8aa42061 |
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07-Dec-2023 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: respect min_ttl_ms with memcgs While investigating kswapd "consuming 100% CPU" [1] (also see "mm/mglru: try to stop at high watermarks"), it was discovered that the memcg LRU can breach the thrashing protection imposed by min_ttl_ms. Before the memcg LRU: kswapd() shrink_node_memcgs() mem_cgroup_iter() inc_max_seq() // always hit a different memcg lru_gen_age_node() mem_cgroup_iter() check the timestamp of the oldest generation After the memcg LRU: kswapd() shrink_many() restart: iterate the memcg LRU: inc_max_seq() // occasionally hit the same memcg if raced with lru_gen_rotate_memcg(): goto restart lru_gen_age_node() mem_cgroup_iter() check the timestamp of the oldest generation Specifically, when the restart happens in shrink_many(), it needs to stick with the (memcg LRU) generation it began with. In other words, it should neither re-read memcg_lru->seq nor age an lruvec of a different generation. Otherwise it can hit the same memcg multiple times without giving lru_gen_age_node() a chance to check the timestamp of that memcg's oldest generation (against min_ttl_ms). [1] https://lore.kernel.org/CAK8fFZ4DY+GtBA40Pm7Nn5xCHy+51w3sfxPqkqpqakSXYyX+Wg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20231208061407.2125867-3-yuzhao@google.com Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists") Signed-off-by: Yu Zhao <yuzhao@google.com> Tested-by: T.J. Mercier <tjmercier@google.com> Cc: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com> Cc: Kairui Song <ryncsn@gmail.com> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5095a2b2 |
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07-Dec-2023 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: try to stop at high watermarks The initial MGLRU patchset didn't include the memcg LRU support, and it relied on should_abort_scan(), added by commit f76c83378851 ("mm: multi-gen LRU: optimize multiple memcgs"), to "backoff to avoid overshooting their aggregate reclaim target by too much". Later on when the memcg LRU was added, should_abort_scan() was deemed unnecessary, and the test results [1] showed no side effects after it was removed by commit a579086c99ed ("mm: multi-gen LRU: remove eviction fairness safeguard"). However, that test used memory.reclaim, which sets nr_to_reclaim to SWAP_CLUSTER_MAX. So it can overshoot only by SWAP_CLUSTER_MAX-1 pages, i.e., from nr_reclaimed=nr_to_reclaim-1 to nr_reclaimed=nr_to_reclaim+SWAP_CLUSTER_MAX-1. Compared with the batch size kswapd sets to nr_to_reclaim, SWAP_CLUSTER_MAX is tiny. Therefore that test isn't able to reproduce the worst case scenario, i.e., kswapd overshooting GBs on large systems and "consuming 100% CPU" (see the Closes tag). Bring back a simplified version of should_abort_scan() on top of the memcg LRU, so that kswapd stops when all eligible zones are above their respective high watermarks plus a small delta to lower the chance of KSWAPD_HIGH_WMARK_HIT_QUICKLY. Note that this only applies to order-0 reclaim, meaning compaction-induced reclaim can still run wild (which is a different problem). On Android, launching 55 apps sequentially: Before After Change pgpgin 838377172 802955040 -4% pgpgout 38037080 34336300 -10% [1] https://lore.kernel.org/20221222041905.2431096-1-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20231208061407.2125867-2-yuzhao@google.com Fixes: a579086c99ed ("mm: multi-gen LRU: remove eviction fairness safeguard") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: Charan Teja Kalla <quic_charante@quicinc.com> Reported-by: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com> Closes: https://lore.kernel.org/CAK8fFZ4DY+GtBA40Pm7Nn5xCHy+51w3sfxPqkqpqakSXYyX+Wg@mail.gmail.com/ Tested-by: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com> Tested-by: Kalesh Singh <kaleshsingh@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Kairui Song <ryncsn@gmail.com> Cc: T.J. Mercier <tjmercier@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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08148805 |
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07-Dec-2023 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: fix underprotected page cache Unmapped folios accessed through file descriptors can be underprotected. Those folios are added to the oldest generation based on: 1. The fact that they are less costly to reclaim (no need to walk the rmap and flush the TLB) and have less impact on performance (don't cause major PFs and can be non-blocking if needed again). 2. The observation that they are likely to be single-use. E.g., for client use cases like Android, its apps parse configuration files and store the data in heap (anon); for server use cases like MySQL, it reads from InnoDB files and holds the cached data for tables in buffer pools (anon). However, the oldest generation can be very short lived, and if so, it doesn't provide the PID controller with enough time to respond to a surge of refaults. (Note that the PID controller uses weighted refaults and those from evicted generations only take a half of the whole weight.) In other words, for a short lived generation, the moving average smooths out the spike quickly. To fix the problem: 1. For folios that are already on LRU, if they can be beyond the tracking range of tiers, i.e., five accesses through file descriptors, move them to the second oldest generation to give them more time to age. (Note that tiers are used by the PID controller to statistically determine whether folios accessed multiple times through file descriptors are worth protecting.) 2. When adding unmapped folios to LRU, adjust the placement of them so that they are not too close to the tail. The effect of this is similar to the above. On Android, launching 55 apps sequentially: Before After Change workingset_refault_anon 25641024 25598972 0% workingset_refault_file 115016834 106178438 -8% Link: https://lkml.kernel.org/r/20231208061407.2125867-1-yuzhao@google.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: Charan Teja Kalla <quic_charante@quicinc.com> Tested-by: Kalesh Singh <kaleshsingh@google.com> Cc: T.J. Mercier <tjmercier@google.com> Cc: Kairui Song <ryncsn@gmail.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8c2214fc |
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03-Oct-2023 |
Jaewon Kim <jaewon31.kim@samsung.com> |
mm: multi-gen LRU: reuse some legacy trace events As the legacy lru provides, the mglru needs some trace events for debugging. Let's reuse following legacy events for the mglru. trace_mm_vmscan_lru_isolate trace_mm_vmscan_lru_shrink_inactive Here's an example mm_vmscan_lru_isolate: classzone=2 order=0 nr_requested=4096 nr_scanned=64 nr_skipped=0 nr_taken=64 lru=inactive_file mm_vmscan_lru_shrink_inactive: nid=0 nr_scanned=64 nr_reclaimed=63 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=1 nr_ref_keep=0 nr_unmap_fail=0 priority=2 flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC Link: https://lkml.kernel.org/r/20231003114155.21869-1-jaewon31.kim@samsung.com Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: SeongJae Park <sj@kernel.org> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: T.J. Mercier <tjmercier@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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76a0fb4f |
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20-Sep-2023 |
liwenyu <wenyuli@ex.bilibili.com> |
delayacct: add memory reclaim delay in get_page_from_freelist The current memory reclaim delay statistics only count the direct memory reclaim of the task in do_try_to_free_pages(). In systems with NUMA open, some tasks occasionally experience slower response times, but the total count of reclaim does not increase, using ftrace can show that node_reclaim has occurred. The memory reclaim occurring in get_page_from_freelist() is also due to heavy memory load. To get the impact of tasks in memory reclaim, this patch adds the statistics of the memory reclaim delay statistics for __node_reclaim(). Link: https://lkml.kernel.org/r/181C946095F0252B+7cc60eca-1abf-4502-aad3-ffd8ef89d910@ex.bilibili.com Signed-off-by: Wen Yu Li <wenyuli@ex.bilibili.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: <wangyun@bilibili.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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3dfbb555 |
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14-Sep-2023 |
Vlastimil Babka <vbabka@suse.cz> |
mm, vmscan: remove ISOLATE_UNMAPPED This isolate_mode_t flag is effectively unused since 89f6c88a6ab4 ("mm: __isolate_lru_page_prepare() in isolate_migratepages_block()") as sc->may_unmap is now checked directly (and only node_reclaim has a mode that sets it to 0). The last remaining place is mm_vmscan_lru_isolate tracepoint for the isolate_mode parameter. That one was mainly used to indicate the active/inactive mode, which the trace-vmscan-postprocess.pl script consumed, but that got silently broken. After fixing the script by the previous patch, it does not need the isolate_mode anymore. So just remove the parameter and with that the whole ISOLATE_UNMAPPED flag. Link: https://lkml.kernel.org/r/20230914131637.12204-4-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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811244a5 |
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13-Sep-2023 |
Xin Hao <vernhao@tencent.com> |
mm: memcg: add THP swap out info for anonymous reclaim At present, we support per-memcg reclaim strategy, however we do not know the number of transparent huge pages being reclaimed, as we know the transparent huge pages need to be splited before reclaim them, and they will bring some performance bottleneck effect. for example, when two memcg (A & B) are doing reclaim for anonymous pages at same time, and 'A' memcg is reclaiming a large number of transparent huge pages, we can better analyze that the performance bottleneck will be caused by 'A' memcg. therefore, in order to better analyze such problems, there add THP swap out info for per-memcg. [akpm@linux-foundation.orgL fix swap_writepage_fs(), per Johannes] Link: https://lkml.kernel.org/r/20230913213343.GB48476@cmpxchg.org Link: https://lkml.kernel.org/r/20230913164938.16918-1-vernhao@tencent.com Signed-off-by: Xin Hao <vernhao@tencent.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ed547ab6 |
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12-Sep-2023 |
liujinlong <liujinlong@kylinos.cn> |
mm: vmscan: modify an easily misunderstood function name When looking at the code in the memory part, I found that the purpose of the function prepare_scan_countis very different from the function name. It is easy to misunderstand when reading.The function prepare_scan_count mainly completes the assignment of the scan_control structure.Therefore, I suggest that the function name can be changed to prepare_scan_control, which is easier to understand. Link: https://lkml.kernel.org/r/20230912085923.27238-1-liujinlong@kylinos.cn Signed-off-by: liujinlong <liujinlong@kylinos.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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96f7b2b9 |
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11-Sep-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: vmscan: move shrinker-related code into a separate file The mm/vmscan.c file is too large, so separate the shrinker-related code from it into a separate file. No functional changes. Link: https://lkml.kernel.org/r/20230911092517.64141-3-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Christian König <christian.koenig@amd.com> Cc: Chuck Lever <cel@kernel.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Price <steven.price@arm.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Abhinav Kumar <quic_abhinavk@quicinc.com> Cc: Alasdair Kergon <agk@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Andreas Gruenbacher <agruenba@redhat.com> Cc: Anna Schumaker <anna@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Bob Peterson <rpeterso@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Carlos Llamas <cmllamas@google.com> Cc: Chandan Babu R <chandan.babu@oracle.com> Cc: Chao Yu <chao@kernel.org> Cc: Chris Mason <clm@fb.com> Cc: Coly Li <colyli@suse.de> Cc: Dai Ngo <Dai.Ngo@oracle.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Airlie <airlied@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Sterba <dsterba@suse.com> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> Cc: Gao Xiang <hsiangkao@linux.alibaba.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Jason Wang <jasowang@redhat.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Jeffle Xu <jefflexu@linux.alibaba.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Marijn Suijten <marijn.suijten@somainline.org> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Mike Snitzer <snitzer@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nadav Amit <namit@vmware.com> Cc: Neil Brown <neilb@suse.de> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Olga Kornievskaia <kolga@netapp.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rob Clark <robdclark@gmail.com> Cc: Rob Herring <robh@kernel.org> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Sean Paul <sean@poorly.run> Cc: Song Liu <song@kernel.org> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com> Cc: Tom Talpey <tom@talpey.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Cc: Yue Hu <huyue2@coolpad.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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037dd8f9 |
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06-Sep-2023 |
Angus Chen <angus.chen@jaguarmicro.com> |
mm/vmscan: print err before panic If panic is enable,the err information will not be printed before bugon, So swap it. Print the return value of PTR_ERR(pgdat->kswapd) also. Link: https://lkml.kernel.org/r/20230906083700.181-1-angus.chen@jaguarmicro.com Signed-off-by: Angus Chen <angus.chen@jaguarmicro.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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97144ce0 |
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25-Aug-2023 |
Vern Hao <vernhao@tencent.com> |
mm/vmscan: use folio_migratetype() instead of get_pageblock_migratetype() In skip_cma(), we can use folio_migratetype() to replace get_pageblock_migratetype(). Link: https://lkml.kernel.org/r/20230825075735.52436-1-user@VERNHAO-MC1 Signed-off-by: Vern Hao <vernhao@tencent.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Zhaoyang Huang <zhaoyang.huang@unisoc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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3d2c9087 |
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21-Aug-2023 |
David Hildenbrand <david@redhat.com> |
mm/swap: inline folio_set_swap_entry() and folio_swap_entry() Let's simply work on the folio directly and remove the helpers. Link: https://lkml.kernel.org/r/20230821160849.531668-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Chris Li <chrisl@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Vitaly Wool <vitaly.wool@konsulko.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b7108d66 |
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09-Aug-2023 |
Charan Teja Kalla <quic_charante@quicinc.com> |
Multi-gen LRU: skip CMA pages when they are not eligible This patch is based on the commit 5da226dbfce3("mm: skip CMA pages when they are not available") which skips cma pages reclaim when they are not eligible for the current allocation context. In mglru, such pages are added to the tail of the immediate generation to maintain better LRU order, which is unlike the case of conventional LRU where such pages are directly added to the head of the LRU list(akin to adding to head of the youngest generation in mglru). No observable issue without this patch on MGLRU, but logically it make sense to skip the CMA page reclaim when those pages can't be satisfied for the current allocation context. Link: https://lkml.kernel.org/r/1691568344-13475-1-git-send-email-quic_charante@quicinc.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zhaoyang Huang <zhaoyang.huang@unisoc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a3235ea2 |
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01-Aug-2023 |
Kalesh Singh <kaleshsingh@google.com> |
Multi-gen LRU: fix can_swap in lru_gen_look_around() walk->can_swap might be invalid since it's not guaranteed to be initialized for the particular lruvec. Instead deduce it from the folio type (anon/file). Link: https://lkml.kernel.org/r/20230802025606.346758-3-kaleshsingh@google.com Fixes: 018ee47f1489 ("mm: multi-gen LRU: exploit locality in rmap") Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> [mediatek] Tested-by: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Oleksandr Natalenko <oleksandr@natalenko.name> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Steven Barrett <steven@liquorix.net> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bb5e7f23 |
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01-Aug-2023 |
Kalesh Singh <kaleshsingh@google.com> |
Multi-gen LRU: avoid race in inc_min_seq() inc_max_seq() will try to inc_min_seq() if nr_gens == MAX_NR_GENS. This is because the generations are reused (the last oldest now empty generation will become the next youngest generation). inc_min_seq() is retried until successful, dropping the lru_lock and yielding the CPU on each failure, and retaking the lock before trying again: while (!inc_min_seq(lruvec, type, can_swap)) { spin_unlock_irq(&lruvec->lru_lock); cond_resched(); spin_lock_irq(&lruvec->lru_lock); } However, the initial condition that required incrementing the min_seq (nr_gens == MAX_NR_GENS) is not retested. This can change by another call to inc_max_seq() from run_aging() with force_scan=true from the debugfs interface. Since the eviction stalls when the nr_gens == MIN_NR_GENS, avoid unnecessarily incrementing the min_seq by rechecking the number of generations before each attempt. This issue was uncovered in previous discussion on the list by Yu Zhao and Aneesh Kumar [1]. [1] https://lore.kernel.org/linux-mm/CAOUHufbO7CaVm=xjEb1avDhHVvnC8pJmGyKcFf2iY_dpf+zR3w@mail.gmail.com/ Link: https://lkml.kernel.org/r/20230802025606.346758-2-kaleshsingh@google.com Fixes: d6c3af7d8a2b ("mm: multi-gen LRU: debugfs interface") Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> [mediatek] Tested-by: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Oleksandr Natalenko <oleksandr@natalenko.name> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Steven Barrett <steven@liquorix.net> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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669281ee |
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01-Aug-2023 |
Kalesh Singh <kaleshsingh@google.com> |
Multi-gen LRU: fix per-zone reclaim MGLRU has a LRU list for each zone for each type (anon/file) in each generation: long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; The min_seq (oldest generation) can progress independently for each type but the max_seq (youngest generation) is shared for both anon and file. This is to maintain a common frame of reference. In order for eviction to advance the min_seq of a type, all the per-zone lists in the oldest generation of that type must be empty. The eviction logic only considers pages from eligible zones for eviction or promotion. scan_folios() { ... for (zone = sc->reclaim_idx; zone >= 0; zone--) { ... sort_folio(); // Promote ... isolate_folio(); // Evict } ... } Consider the system has the movable zone configured and default 4 generations. The current state of the system is as shown below (only illustrating one type for simplicity): Type: ANON Zone DMA32 Normal Movable Device Gen 0 0 0 4GB 0 Gen 1 0 1GB 1MB 0 Gen 2 1MB 4GB 1MB 0 Gen 3 1MB 1MB 1MB 0 Now consider there is a GFP_KERNEL allocation request (eligible zone index <= Normal), evict_folios() will return without doing any work since there are no pages to scan in the eligible zones of the oldest generation. Reclaim won't make progress until triggered from a ZONE_MOVABLE allocation request; which may not happen soon if there is a lot of free memory in the movable zone. This can lead to OOM kills, although there is 1GB pages in the Normal zone of Gen 1 that we have not yet tried to reclaim. This issue is not seen in the conventional active/inactive LRU since there are no per-zone lists. If there are no (not enough) folios to scan in the eligible zones, move folios from ineligible zone (zone_index > reclaim_index) to the next generation. This allows for the progression of min_seq and reclaiming from the next generation (Gen 1). Qualcomm, Mediatek and raspberrypi [1] discovered this issue independently. [1] https://github.com/raspberrypi/linux/issues/5395 Link: https://lkml.kernel.org/r/20230802025606.346758-1-kaleshsingh@google.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Reported-by: Charan Teja Kalla <quic_charante@quicinc.com> Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> [mediatek] Tested-by: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Barry Song <baohua@kernel.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Oleksandr Natalenko <oleksandr@natalenko.name> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Steven Barrett <steven@liquorix.net> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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0201ebf2 |
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28-Jun-2023 |
David Howells <dhowells@redhat.com> |
mm: merge folio_has_private()/filemap_release_folio() call pairs Patch series "mm, netfs, fscache: Stop read optimisation when folio removed from pagecache", v7. This fixes an optimisation in fscache whereby we don't read from the cache for a particular file until we know that there's data there that we don't have in the pagecache. The problem is that I'm no longer using PG_fscache (aka PG_private_2) to indicate that the page is cached and so I don't get a notification when a cached page is dropped from the pagecache. The first patch merges some folio_has_private() and filemap_release_folio() pairs and introduces a helper, folio_needs_release(), to indicate if a release is required. The second patch is the actual fix. Following Willy's suggestions[1], it adds an AS_RELEASE_ALWAYS flag to an address_space that will make filemap_release_folio() always call ->release_folio(), even if PG_private/PG_private_2 aren't set. folio_needs_release() is altered to add a check for this. This patch (of 2): Make filemap_release_folio() check folio_has_private(). Then, in most cases, where a call to folio_has_private() is immediately followed by a call to filemap_release_folio(), we can get rid of the test in the pair. There are a couple of sites in mm/vscan.c that this can't so easily be done. In shrink_folio_list(), there are actually three cases (something different is done for incompletely invalidated buffers), but filemap_release_folio() elides two of them. In shrink_active_list(), we don't have have the folio lock yet, so the check allows us to avoid locking the page unnecessarily. A wrapper function to check if a folio needs release is provided for those places that still need to do it in the mm/ directory. This will acquire additional parts to the condition in a future patch. After this, the only remaining caller of folio_has_private() outside of mm/ is a check in fuse. Link: https://lkml.kernel.org/r/20230628104852.3391651-1-dhowells@redhat.com Link: https://lkml.kernel.org/r/20230628104852.3391651-2-dhowells@redhat.com Reported-by: Rohith Surabattula <rohiths.msft@gmail.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: David Howells <dhowells@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steve French <sfrench@samba.org> Cc: Shyam Prasad N <nspmangalore@gmail.com> Cc: Rohith Surabattula <rohiths.msft@gmail.com> Cc: Dave Wysochanski <dwysocha@redhat.com> Cc: Dominique Martinet <asmadeus@codewreck.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Xiubo Li <xiubli@redhat.com> Cc: Jingbo Xu <jefflexu@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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6867c7a3 |
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14-Aug-2023 |
T.J. Mercier <tjmercier@google.com> |
mm: multi-gen LRU: don't spin during memcg release When a memcg is in the process of being released mem_cgroup_tryget will fail because its reference count has already reached 0. This can happen during reclaim if the memcg has already been offlined, and we reclaim all remaining pages attributed to the offlined memcg. shrink_many attempts to skip the empty memcg in this case, and continue reclaiming from the remaining memcgs in the old generation. If there is only one memcg remaining, or if all remaining memcgs are in the process of being released then shrink_many will spin until all memcgs have finished being released. The release occurs through a workqueue, so it can take a while before kswapd is able to make any further progress. This fix results in reductions in kswapd activity and direct reclaim in a test where 28 apps (working set size > total memory) are repeatedly launched in a random sequence: A B delta ratio(%) allocstall_movable 5962 3539 -2423 -40.64 allocstall_normal 2661 2417 -244 -9.17 kswapd_high_wmark_hit_quickly 53152 7594 -45558 -85.71 pageoutrun 57365 11750 -45615 -79.52 Link: https://lkml.kernel.org/r/20230814151636.1639123-1-tjmercier@google.com Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists") Signed-off-by: T.J. Mercier <tjmercier@google.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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49b06385 |
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04-Aug-2023 |
Suren Baghdasaryan <surenb@google.com> |
mm: enable page walking API to lock vmas during the walk walk_page_range() and friends often operate under write-locked mmap_lock. With introduction of vma locks, the vmas have to be locked as well during such walks to prevent concurrent page faults in these areas. Add an additional member to mm_walk_ops to indicate locking requirements for the walk. The change ensures that page walks which prevent concurrent page faults by write-locking mmap_lock, operate correctly after introduction of per-vma locks. With per-vma locks page faults can be handled under vma lock without taking mmap_lock at all, so write locking mmap_lock would not stop them. The change ensures vmas are properly locked during such walks. A sample issue this solves is do_mbind() performing queue_pages_range() to queue pages for migration. Without this change a concurrent page can be faulted into the area and be left out of migration. Link: https://lkml.kernel.org/r/20230804152724.3090321-2-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org> Suggested-by: Jann Horn <jannh@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michel Lespinasse <michel@lespinasse.org> Cc: Peter Xu <peterx@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1bc545bf |
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20-Jun-2023 |
Yosry Ahmed <yosryahmed@google.com> |
mm/vmscan: fix root proactive reclaim unthrottling unbalanced node When memory.reclaim was introduced, it became the first case where cgroup_reclaim() is true for the root cgroup. Johannes concluded [1] that for most cases this is okay, except for one case. Historically, kswapd would throttle reclaim on a node if a lot of pages marked for reclaim are under writeback (aka the node is congested). This occurred by setting LRUVEC_CONGESTED bit in lruvec->flags. The bit would be cleared when the node is balanced. Similarly, cgroup reclaim would set the same bit when an lruvec is congested, and clear it on the way out of reclaim (to throttle local reclaimers). Before the introduction of memory.reclaim, the root memcg was the only target of kswapd reclaim, and non-root memcgs were the only targets of cgroup reclaim, so they would never interfere. Using the same bit for both was fine. After memory.reclaim, it is possible for cgroup reclaim on the root cgroup to clear the bit set by kswapd. This would result in reclaim on the node to be unthrottled before the node is balanced. Fix this by introducing separate bits for cgroup-level and node-level congestion. kswapd can unthrottle an lruvec that is marked as congested by cgroup reclaim (as the entire node should no longer be congested), but not vice versa (to prevent premature unthrottling before the entire node is balanced). [1]https://lore.kernel.org/lkml/20230405200150.GA35884@cmpxchg.org/ Link: https://lkml.kernel.org/r/20230621023101.432780-1-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Reported-by: Johannes Weiner <hannes@cmpxchg.org> Closes: https://lore.kernel.org/lkml/20230405200150.GA35884@cmpxchg.org/ Cc: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7a704474 |
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20-Jun-2023 |
Yosry Ahmed <yosryahmed@google.com> |
mm: memcg: rename and document global_reclaim() Evidently, global_reclaim() can be a confusing name. Especially that it used to exist before with a subtly different definition (removed by commit b5ead35e7e1d ("mm: vmscan: naming fixes: global_reclaim() and sane_reclaim()"). It can be interpreted as non-cgroup reclaim, even though it returns true for cgroup reclaim on the root memcg (through memory.reclaim). Rename it to root_reclaim() in an attempt to make it less ambiguous, and add documentation to it as well as cgroup_reclaim. Link: https://lkml.kernel.org/r/20230621023053.432374-1-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Reported-by: Johannes Weiner <hannes@cmpxchg.org> Closes: https://lore.kernel.org/lkml/20230405200150.GA35884@cmpxchg.org/ Acked-by: Yu Zhao <yuzhao@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e0b72c14 |
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21-Jun-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: remove check_move_unevictable_pages() All callers have now been converted to call check_move_unevictable_folios(). Link: https://lkml.kernel.org/r/20230621164557.3510324-7-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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814bc1de |
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19-Jun-2023 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: make memcg_lru->lock irq safe lru_gen_rotate_memcg() can happen in softirq if memory.soft_limit_in_bytes is set. This requires memcg_lru->lock to be irq safe. Lockdep warns on this. This problem only affects memcg v1. Link: https://lkml.kernel.org/r/20230619193821.2710944-1-yuzhao@google.com Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: syzbot+87c490fd2be656269b6a@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=87c490fd2be656269b6a Reviewed-by: Yosry Ahmed <yosryahmed@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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c33c7948 |
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12-Jun-2023 |
Ryan Roberts <ryan.roberts@arm.com> |
mm: ptep_get() conversion Convert all instances of direct pte_t* dereferencing to instead use ptep_get() helper. This means that by default, the accesses change from a C dereference to a READ_ONCE(). This is technically the correct thing to do since where pgtables are modified by HW (for access/dirty) they are volatile and therefore we should always ensure READ_ONCE() semantics. But more importantly, by always using the helper, it can be overridden by the architecture to fully encapsulate the contents of the pte. Arch code is deliberately not converted, as the arch code knows best. It is intended that arch code (arm64) will override the default with its own implementation that can (e.g.) hide certain bits from the core code, or determine young/dirty status by mixing in state from another source. Conversion was done using Coccinelle: ---- // $ make coccicheck \ // COCCI=ptepget.cocci \ // SPFLAGS="--include-headers" \ // MODE=patch virtual patch @ depends on patch @ pte_t *v; @@ - *v + ptep_get(v) ---- Then reviewed and hand-edited to avoid multiple unnecessary calls to ptep_get(), instead opting to store the result of a single call in a variable, where it is correct to do so. This aims to negate any cost of READ_ONCE() and will benefit arch-overrides that may be more complex. Included is a fix for an issue in an earlier version of this patch that was pointed out by kernel test robot. The issue arose because config MMU=n elides definition of the ptep helper functions, including ptep_get(). HUGETLB_PAGE=n configs still define a simple huge_ptep_clear_flush() for linking purposes, which dereferences the ptep. So when both configs are disabled, this caused a build error because ptep_get() is not defined. Fix by continuing to do a direct dereference when MMU=n. This is safe because for this config the arch code cannot be trying to virtualize the ptes because none of the ptep helpers are defined. Link: https://lkml.kernel.org/r/20230612151545.3317766-4-ryan.roberts@arm.com Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/ Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Potapenko <glider@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Dave Airlie <airlied@gmail.com> Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: SeongJae Park <sj@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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52fc0483 |
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08-Jun-2023 |
Hugh Dickins <hughd@google.com> |
mm/mglru: allow pte_offset_map_nolock() to fail MGLRU's walk_pte_range() use the safer pte_offset_map_nolock(), rather than pte_lockptr(), to get the ptl for its trylock. Just return false and move on to next extent if it fails, like when the trylock fails. Remove the VM_WARN_ON_ONCE(pmd_leaf) since that will happen, rarely. Link: https://lkml.kernel.org/r/51ece73e-7398-2e4a-2384-56708c87844f@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Zack Rusin <zackr@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e5797dc0 |
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06-Jun-2023 |
Miaohe Lin <linmiaohe@huawei.com> |
mm: vmscan: mark kswapd_run() and kswapd_stop() __meminit Add __meminit to kswapd_run() and kswapd_stop() to ensure they're default to __init when memory hotplug is not enabled. Link: https://lkml.kernel.org/r/20230606121813.242163-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Yu Zhao <yuzhao@google.com> Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5da226db |
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30-May-2023 |
Zhaoyang Huang <zhaoyang.huang@unisoc.com> |
mm: skip CMA pages when they are not available This patch fixes unproductive reclaiming of CMA pages by skipping them when they are not available for current context. It arises from the below OOM issue, which was caused by a large proportion of MIGRATE_CMA pages among free pages. [ 36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0 [ 36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB [ 36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB ... [ 36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC) [ 36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0 [ 36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0 This change further decreases the chance for wrong OOMs in the presence of a lot of CMA memory. [david@redhat.com: changelog addition] Link: https://lkml.kernel.org/r/1685501461-19290-1-git-send-email-zhaoyang.huang@unisoc.com Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: ke.wang <ke.wang@unisoc.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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71c3ad65 |
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09-Jun-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
Revert "mm: vmscan: make global slab shrink lockless" This reverts commit f95bdb700bc6bb74e1199b1f5f90c613e152cfa7. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. After discussion, we will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So revert the shrinker_srcu related changes first. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-8-qi.zheng@linux.dev Reported-by: kernel test robot <yujie.liu@intel.com> Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7cee3603 |
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09-Jun-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
Revert "mm: vmscan: make memcg slab shrink lockless" This reverts commit caa05325c9126c77ebf114edce51536a0d0a9a08. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. After discussion, we will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So revert the shrinker_srcu related changes first. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-7-qi.zheng@linux.dev Reported-by: kernel test robot <yujie.liu@intel.com> Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d6ecbcd7 |
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09-Jun-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
Revert "mm: vmscan: add shrinker_srcu_generation" This reverts commit 475733dda5aedba9e086379aafe6b5ffd53e8f5e. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. We will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So revert the shrinker_srcu related changes first. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-6-qi.zheng@linux.dev Reported-by: kernel test robot <yujie.liu@intel.com> Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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c534f7cc |
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09-Jun-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
Revert "mm: vmscan: hold write lock to reparent shrinker nr_deferred" This reverts commit b3cabea3c9153fd42fe5cb851ac58b51ea2b32b8. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. We will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. Because there will be other readers after reverting the shrinker_srcu related changes, so it is better to restore to hold read lock to reparent shrinker nr_deferred. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-4-qi.zheng@linux.dev Reported-by: kernel test robot <yujie.liu@intel.com> Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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07252b0f |
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09-Jun-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
Revert "mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers()" This reverts commit 1643db98d9b314e0a592d152603094fbf7ab906e. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. We will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So we still need shrinker_rwsem in synchronize_shrinkers() after reverting the shrinker_srcu related changes. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-3-qi.zheng@linux.dev Reported-by: kernel test robot <yujie.liu@intel.com> Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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47a7c01c |
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09-Jun-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
Revert "mm: shrinkers: convert shrinker_rwsem to mutex" Patch series "revert shrinker_srcu related changes". This patch (of 7): This reverts commit cf2e309ebca7bb0916771839f9b580b06c778530. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. After discussion, we will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So revert the shrinker_mutex back to shrinker_rwsem first. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-1-qi.zheng@linux.dev Link: https://lkml.kernel.org/r/20230609081518.3039120-2-qi.zheng@linux.dev Reported-by: kernel test robot <yujie.liu@intel.com> Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Kirill Tkhai <tkhai@ya.ru> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yujie Liu <yujie.liu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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501b2651 |
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30-May-2023 |
Marcelo Tosatti <mtosatti@redhat.com> |
vmstat: allow_direct_reclaim should use zone_page_state_snapshot A customer provided evidence indicating that a process was stalled in direct reclaim: - The process was trapped in throttle_direct_reclaim(). The function wait_event_killable() was called to wait condition allow_direct_reclaim(pgdat) for current node to be true. The allow_direct_reclaim(pgdat) examined the number of free pages on the node by zone_page_state() which just returns value in zone->vm_stat[NR_FREE_PAGES]. - On node #1, zone->vm_stat[NR_FREE_PAGES] was 0. However, the freelist on this node was not empty. - This inconsistent of vmstat value was caused by percpu vmstat on nohz_full cpus. Every increment/decrement of vmstat is performed on percpu vmstat counter at first, then pooled diffs are cumulated to the zone's vmstat counter in timely manner. However, on nohz_full cpus (in case of this customer's system, 48 of 52 cpus) these pooled diffs were not cumulated once the cpu had no event on it so that the cpu started sleeping infinitely. I checked percpu vmstat and found there were total 69 counts not cumulated to the zone's vmstat counter yet. - In this situation, kswapd did not help the trapped process. In pgdat_balanced(), zone_wakermark_ok_safe() examined the number of free pages on the node by zone_page_state_snapshot() which checks pending counts on percpu vmstat. Therefore kswapd could know there were 69 free pages correctly. Since zone->_watermark = {8, 20, 32}, kswapd did not work because 69 was greater than 32 as high watermark. Change allow_direct_reclaim to use zone_page_state_snapshot, which allows a more precise version of the vmstat counters to be used. allow_direct_reclaim will only be called from try_to_free_pages, which is not a hot path. Testing: Due to difficulties accessing the system, it has not been possible for the reproducer to test the patch (however its clear from available data and analysis that it should fix it). Link: https://lkml.kernel.org/r/20230530145335.677325196@redhat.com Reviewed-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Aaron Tomlin <atomlin@atomlin.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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3af0191a |
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23-May-2023 |
Kalesh Singh <kaleshsingh@google.com> |
Multi-gen LRU: fix workingset accounting On Android app cycle workloads, MGLRU showed a significant reduction in workingset refaults although pgpgin/pswpin remained relatively unchanged. This indicated MGLRU may be undercounting workingset refaults. This has impact on userspace programs, like Android's LMKD, that monitor workingset refault statistics to detect thrashing. It was found that refaults were only accounted if the MGLRU shadow entry was for a recently evicted folio. However, recently evicted folios should be accounted as workingset activation, and refaults should be accounted regardless of recency. Fix MGLRU's workingset refault and activation accounting to more closely match that of the conventional active/inactive LRU. Link: https://lkml.kernel.org/r/20230523205922.3852731-1-kaleshsingh@google.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Reported-by: Charan Teja Kalla <quic_charante@quicinc.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Cc: Oleksandr Natalenko <oleksandr@natalenko.name> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bd02df41 |
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22-May-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: add helpers in page table walks Add helpers to page table walking code: - Clarifies intent via name "should_walk_mmu" and "should_clear_pmd_young" - Avoids repeating same logic in two places Link: https://lkml.kernel.org/r/20230522112058.2965866-3-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Reviewed-by: Yuanchu Xie <yuanchu@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5c7e7a0d |
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22-May-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: cleanup lru_gen_soft_reclaim() lru_gen_soft_reclaim() gets the lruvec from the memcg and node ID to keep a cleaner interface on the caller side. Link: https://lkml.kernel.org/r/20230522112058.2965866-2-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Reviewed-by: Yuanchu Xie <yuanchu@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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0285762c |
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22-May-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: use macro for bitmap Use DECLARE_BITMAP macro when possible. Link: https://lkml.kernel.org/r/20230522112058.2965866-1-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Yuanchu Xie <yuanchu@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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3cf04937 |
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02-Jun-2023 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: compaction: have compaction_suitable() return bool Since it only returns COMPACT_CONTINUE or COMPACT_SKIPPED now, a bool return value simplifies the callsites. Link: https://lkml.kernel.org/r/20230602151204.GD161817@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f98a497e |
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19-May-2023 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: compaction: remove unnecessary is_via_compact_memory() checks Remove from all paths not reachable via /proc/sys/vm/compact_memory. Link: https://lkml.kernel.org/r/20230519123959.77335-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e8606320 |
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19-May-2023 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: compaction: refactor __compaction_suitable() __compaction_suitable() is supposed to check for available migration targets. However, it also checks whether the operation was requested via /proc/sys/vm/compact_memory, and whether the original allocation request can already succeed. These don't apply to all callsites. Move the checks out to the callers, so that later patches can deal with them one by one. No functional change intended. [hannes@cmpxchg.org: fix comment, per Vlastimil] Link: https://lkml.kernel.org/r/20230602144942.GC161817@cmpxchg.org Link: https://lkml.kernel.org/r/20230519123959.77335-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4e096ae1 |
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12-May-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: convert migrate_pages() to work on folios Almost all of the callers & implementors of migrate_pages() were already converted to use folios. compaction_alloc() & compaction_free() are trivial to convert a part of this patch and not worth splitting out. Link: https://lkml.kernel.org/r/20230513001101.276972-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5221b5a8 |
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16-May-2023 |
Kefeng Wang <wangkefeng.wang@huawei.com> |
mm: vmscan: use gfp_has_io_fs() Use gfp_has_io_fs() instead of open-code. Link: https://lkml.kernel.org/r/20230516063821.121844-12-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Len Brown <len.brown@intel.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Machek <pavel@ucw.cz> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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26e239b3 |
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02-May-2023 |
Joan Bruguera Micó <joanbrugueram@gmail.com> |
mm: shrinkers: fix race condition on debugfs cleanup When something registers and unregisters many shrinkers, such as: for x in $(seq 10000); do unshare -Ui true; done Sometimes the following error is printed to the kernel log: debugfs: Directory '...' with parent 'shrinker' already present! This occurs since commit badc28d4924b ("mm: shrinkers: fix deadlock in shrinker debugfs") / v6.2: Since the call to `debugfs_remove_recursive` was moved outside the `shrinker_rwsem`/`shrinker_mutex` lock, but the call to `ida_free` stayed inside, a newly registered shrinker can be re-assigned that ID and attempt to create the debugfs directory before the directory from the previous shrinker has been removed. The locking changes in commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless") made the race condition more likely, though it existed before then. Commit badc28d4924b ("mm: shrinkers: fix deadlock in shrinker debugfs") could be reverted since the issue is addressed should no longer occur since the count and scan operations are lockless since commit 20cd1892fcc3 ("mm: shrinkers: make count and scan in shrinker debugfs lockless"). However, since this is a contended lock, prefer instead moving `ida_free` outside the lock to avoid the race. Link: https://lkml.kernel.org/r/20230503013232.299211-1-joanbrugueram@gmail.com Fixes: badc28d4924b ("mm: shrinkers: fix deadlock in shrinker debugfs") Signed-off-by: Joan Bruguera Micó <joanbrugueram@gmail.com> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d824ec2a |
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28-Apr-2023 |
Jan Kara <jack@suse.cz> |
mm: do not reclaim private data from pinned page If the page is pinned, there's no point in trying to reclaim it. Furthermore if the page is from the page cache we don't want to reclaim fs-private data from the page because the pinning process may be writing to the page at any time and reclaiming fs private info on a dirty page can upset the filesystem (see link below). Link: https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz Link: https://lkml.kernel.org/r/20230428124140.30166-1-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7f63cf2d |
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13-Apr-2023 |
Kalesh Singh <kaleshsingh@google.com> |
mm: Multi-gen LRU: remove wait_event_killable() Android 14 and later default to MGLRU [1] and field telemetry showed occasional long tail latency (>100ms) in the reclaim path. Tracing revealed priority inversion in the reclaim path. In try_to_inc_max_seq(), when high priority tasks were blocked on wait_event_killable(), the preemption of the low priority task to call wake_up_all() caused those high priority tasks to wait longer than necessary. In general, this problem is not different from others of its kind, e.g., one caused by mutex_lock(). However, it is specific to MGLRU because it introduced the new wait queue lruvec->mm_state.wait. The purpose of this new wait queue is to avoid the thundering herd problem. If many direct reclaimers rush into try_to_inc_max_seq(), only one can succeed, i.e., the one to wake up the rest, and the rest who failed might cause premature OOM kills if they do not wait. So far there is no evidence supporting this scenario, based on how often the wait has been hit. And this begs the question how useful the wait queue is in practice. Based on Minchan's recommendation, which is in line with his commit 6d4675e60135 ("mm: don't be stuck to rmap lock on reclaim path") and the rest of the MGLRU code which also uses trylock when possible, remove the wait queue. [1] https://android-review.googlesource.com/q/I7ed7fbfd6ef9ce10053347528125dd98c39e50bf Link: https://lkml.kernel.org/r/20230413214326.2147568-1-kaleshsingh@google.com Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Suggested-by: Minchan Kim <minchan@kernel.org> Reported-by: Wei Wang <wvw@google.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Cc: Oleksandr Natalenko <oleksandr@natalenko.name> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ef05e689 |
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13-Apr-2023 |
Yosry Ahmed <yosryahmed@google.com> |
mm: vmscan: move set_task_reclaim_state() near flush_reclaim_state() Move set_task_reclaim_state() near flush_reclaim_state() so that all helpers manipulating reclaim_state are in close proximity. Link: https://lkml.kernel.org/r/20230413104034.1086717-3-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: NeilBrown <neilb@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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583c27a1 |
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13-Apr-2023 |
Yosry Ahmed <yosryahmed@google.com> |
mm: vmscan: ignore non-LRU-based reclaim in memcg reclaim Patch series "Ignore non-LRU-based reclaim in memcg reclaim", v6. Upon running some proactive reclaim tests using memory.reclaim, we noticed some tests flaking where writing to memory.reclaim would be successful even though we did not reclaim the requested amount fully Looking further into it, I discovered that *sometimes* we overestimate the number of reclaimed pages in memcg reclaim. Reclaimed pages through other means than LRU-based reclaim are tracked through reclaim_state in struct scan_control, which is stashed in current task_struct. These pages are added to the number of reclaimed pages through LRUs. For memcg reclaim, these pages generally cannot be linked to the memcg under reclaim and can cause an overestimated count of reclaimed pages. This short series tries to address that. Patch 1 ignores pages reclaimed outside of LRU reclaim in memcg reclaim. The pages are uncharged anyway, so even if we end up under-reporting reclaimed pages we will still succeed in making progress during charging. Patches 2-3 are just refactoring. Patch 2 moves set_reclaim_state() helper next to flush_reclaim_state(). Patch 3 adds a helper that wraps updating current->reclaim_state, and renames reclaim_state->reclaimed_slab to reclaim_state->reclaimed. This patch (of 3): We keep track of different types of reclaimed pages through reclaim_state->reclaimed_slab, and we add them to the reported number of reclaimed pages. For non-memcg reclaim, this makes sense. For memcg reclaim, we have no clue if those pages are charged to the memcg under reclaim. Slab pages are shared by different memcgs, so a freed slab page may have only been partially charged to the memcg under reclaim. The same goes for clean file pages from pruned inodes (on highmem systems) or xfs buffer pages, there is no simple way to currently link them to the memcg under reclaim. Stop reporting those freed pages as reclaimed pages during memcg reclaim. This should make the return value of writing to memory.reclaim, and may help reduce unnecessary reclaim retries during memcg charging. Writing to memory.reclaim on the root memcg is considered as cgroup_reclaim(), but for this case we want to include any freed pages, so use the global_reclaim() check instead of !cgroup_reclaim(). Generally, this should make the return value of try_to_free_mem_cgroup_pages() more accurate. In some limited cases (e.g. freed a slab page that was mostly charged to the memcg under reclaim), the return value of try_to_free_mem_cgroup_pages() can be underestimated, but this should be fine. The freed pages will be uncharged anyway, and we can charge the memcg the next time around as we usually do memcg reclaim in a retry loop. Link: https://lkml.kernel.org/r/20230413104034.1086717-1-yosryahmed@google.com Link: https://lkml.kernel.org/r/20230413104034.1086717-2-yosryahmed@google.com Fixes: f2fe7b09a52b ("mm: memcg/slab: charge individual slab objects instead of pages") Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: David Rientjes <rientjes@google.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: NeilBrown <neilb@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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54c4fe08 |
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11-Apr-2023 |
Haifeng Xu <haifeng.xu@shopee.com> |
mm/vmscan: simplify shrink_node() The difference between sc->nr_reclaimed and nr_reclaimed is computed three times. Introduce a new variable to record the value, so it only needs to be computed once. Link: https://lkml.kernel.org/r/20230411061757.12041-1-haifeng.xu@shopee.com Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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0d856cfe |
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30-Mar-2023 |
Yosry Ahmed <yosryahmed@google.com> |
vmscan: memcg: sleep when flushing stats during reclaim Memory reclaim is a sleepable context. Flushing is an expensive operaiton that scales with the number of cpus and the number of cgroups in the system, so avoid doing it atomically unnecessarily. This can slow down reclaim code if flushing stats is taking too long, but there is already multiple cond_resched()'s in reclaim code. Link: https://lkml.kernel.org/r/20230330191801.1967435-8-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Tejun Heo <tj@kernel.org> Cc: Vasily Averin <vasily.averin@linux.dev> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9fad9aee |
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30-Mar-2023 |
Yosry Ahmed <yosryahmed@google.com> |
memcg: sleep during flushing stats in safe contexts Currently, all contexts that flush memcg stats do so with sleeping not allowed. Some of these contexts are perfectly safe to sleep in, such as reading cgroup files from userspace or the background periodic flusher. Flushing is an expensive operation that scales with the number of cpus and the number of cgroups in the system, so avoid doing it atomically where possible. Refactor the code to make mem_cgroup_flush_stats() non-atomic (aka sleepable), and provide a separate atomic version. The atomic version is used in reclaim, refault, writeback, and in mem_cgroup_usage(). All other code paths are left to use the non-atomic version. This includes callbacks for userspace reads and the periodic flusher. Since refault is the only caller of mem_cgroup_flush_stats_ratelimited(), change it to mem_cgroup_flush_stats_atomic_ratelimited(). Reclaim and refault code paths are modified to do non-atomic flushing in separate later patches -- so it will eventually be changed back to mem_cgroup_flush_stats_ratelimited(). Link: https://lkml.kernel.org/r/20230330191801.1967435-6-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Tejun Heo <tj@kernel.org> Cc: Vasily Averin <vasily.averin@linux.dev> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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23baf831 |
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15-Mar-2023 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
mm, treewide: redefine MAX_ORDER sanely MAX_ORDER currently defined as number of orders page allocator supports: user can ask buddy allocator for page order between 0 and MAX_ORDER-1. This definition is counter-intuitive and lead to number of bugs all over the kernel. Change the definition of MAX_ORDER to be inclusive: the range of orders user can ask from buddy allocator is 0..MAX_ORDER now. [kirill@shutemov.name: fix min() warning] Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box [akpm@linux-foundation.org: fix another min_t warning] [kirill@shutemov.name: fixups per Zi Yan] Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name [akpm@linux-foundation.org: fix underlining in docs] Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/ Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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cf2e309e |
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13-Mar-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: shrinkers: convert shrinker_rwsem to mutex Now there are no readers of shrinker_rwsem, so we can simply replace it with mutex lock. Link: https://lkml.kernel.org/r/20230313112819.38938-9-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1643db98 |
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13-Mar-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers() Currently, the synchronize_shrinkers() is only used by TTM pool. It only requires that no shrinkers run in parallel, and doesn't care about registering and unregistering of shrinkers. Since slab shrink is protected by SRCU, synchronize_srcu() is sufficient to ensure that no shrinker is running in parallel. So the shrinker_rwsem in synchronize_shrinkers() is no longer needed, just remove it. Link: https://lkml.kernel.org/r/20230313112819.38938-8-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b3cabea3 |
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13-Mar-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: vmscan: hold write lock to reparent shrinker nr_deferred For now, reparent_shrinker_deferred() is the only holder of read lock of shrinker_rwsem. And it already holds the global cgroup_mutex, so it will not be called in parallel. Therefore, in order to convert shrinker_rwsem to shrinker_mutex later, here we change to hold the write lock of shrinker_rwsem to reparent. Link: https://lkml.kernel.org/r/20230313112819.38938-7-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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475733dd |
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13-Mar-2023 |
Kirill Tkhai <tkhai@ya.ru> |
mm: vmscan: add shrinker_srcu_generation After we make slab shrink lockless with SRCU, the longest sleep unregister_shrinker() will be a sleep waiting for all do_shrink_slab() calls. To avoid long unbreakable action in the unregister_shrinker(), add shrinker_srcu_generation to restore a check similar to the rwsem_is_contendent() check that we had before. And for memcg slab shrink, we unlock SRCU and continue iterations from the next shrinker id. Link: https://lkml.kernel.org/r/20230313112819.38938-5-zhengqi.arch@bytedance.com Signed-off-by: Kirill Tkhai <tkhai@ya.ru> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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caa05325 |
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13-Mar-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: vmscan: make memcg slab shrink lockless Like global slab shrink, this commit also uses SRCU to make memcg slab shrink lockless. We can reproduce the down_read_trylock() hotspot through the following script: ``` DIR="/root/shrinker/memcg/mnt" do_create() { mkdir -p /sys/fs/cgroup/memory/test mkdir -p /sys/fs/cgroup/perf_event/test echo 4G > /sys/fs/cgroup/memory/test/memory.limit_in_bytes for i in `seq 0 $1`; do mkdir -p /sys/fs/cgroup/memory/test/$i; echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs; echo $$ > /sys/fs/cgroup/perf_event/test/cgroup.procs; mkdir -p $DIR/$i; done } do_mount() { for i in `seq $1 $2`; do mount -t tmpfs $i $DIR/$i; done } do_touch() { for i in `seq $1 $2`; do echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs; echo $$ > /sys/fs/cgroup/perf_event/test/cgroup.procs; dd if=/dev/zero of=$DIR/$i/file$i bs=1M count=1 & done } case "$1" in touch) do_touch $2 $3 ;; test) do_create 4000 do_mount 0 4000 do_touch 0 3000 ;; *) exit 1 ;; esac ``` Save the above script, then run test and touch commands. Then we can use the following perf command to view hotspots: perf top -U -F 999 1) Before applying this patchset: 32.31% [kernel] [k] down_read_trylock 19.40% [kernel] [k] pv_native_safe_halt 16.24% [kernel] [k] up_read 15.70% [kernel] [k] shrink_slab 4.69% [kernel] [k] _find_next_bit 2.62% [kernel] [k] shrink_node 1.78% [kernel] [k] shrink_lruvec 0.76% [kernel] [k] do_shrink_slab 2) After applying this patchset: 27.83% [kernel] [k] _find_next_bit 16.97% [kernel] [k] shrink_slab 15.82% [kernel] [k] pv_native_safe_halt 9.58% [kernel] [k] shrink_node 8.31% [kernel] [k] shrink_lruvec 5.64% [kernel] [k] do_shrink_slab 3.88% [kernel] [k] mem_cgroup_iter At the same time, we use the following perf command to capture IPC information: perf stat -e cycles,instructions -G test -a --repeat 5 -- sleep 10 1) Before applying this patchset: Performance counter stats for 'system wide' (5 runs): 454187219766 cycles test ( +- 1.84% ) 78896433101 instructions test # 0.17 insn per cycle ( +- 0.44% ) 10.0020430 +- 0.0000366 seconds time elapsed ( +- 0.00% ) 2) After applying this patchset: Performance counter stats for 'system wide' (5 runs): 841954709443 cycles test ( +- 15.80% ) (98.69%) 527258677936 instructions test # 0.63 insn per cycle ( +- 15.11% ) (98.68%) 10.01064 +- 0.00831 seconds time elapsed ( +- 0.08% ) We can see that IPC drops very seriously when calling down_read_trylock() at high frequency. After using SRCU, the IPC is at a normal level. Link: https://lkml.kernel.org/r/20230313112819.38938-4-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Vlastimil Babka <Vbabka@suse.cz> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f95bdb70 |
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13-Mar-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: vmscan: make global slab shrink lockless The shrinker_rwsem is a global read-write lock in shrinkers subsystem, which protects most operations such as slab shrink, registration and unregistration of shrinkers, etc. This can easily cause problems in the following cases. 1) When the memory pressure is high and there are many filesystems mounted or unmounted at the same time, slab shrink will be affected (down_read_trylock() failed). Such as the real workload mentioned by Kirill Tkhai: ``` One of the real workloads from my experience is start of an overcommitted node containing many starting containers after node crash (or many resuming containers after reboot for kernel update). In these cases memory pressure is huge, and the node goes round in long reclaim. ``` 2) If a shrinker is blocked (such as the case mentioned in [1]) and a writer comes in (such as mount a fs), then this writer will be blocked and cause all subsequent shrinker-related operations to be blocked. Even if there is no competitor when shrinking slab, there may still be a problem. If we have a long shrinker list and we do not reclaim enough memory with each shrinker, then the down_read_trylock() may be called with high frequency. Because of the poor multicore scalability of atomic operations, this can lead to a significant drop in IPC (instructions per cycle). So many times in history ([2],[3],[4],[5]), some people wanted to replace shrinker_rwsem trylock with SRCU in the slab shrink, but all these patches were abandoned because SRCU was not unconditionally enabled. But now, since commit 1cd0bd06093c ("rcu: Remove CONFIG_SRCU"), the SRCU is unconditionally enabled. So it's time to use SRCU to protect readers who previously held shrinker_rwsem. This commit uses SRCU to make global slab shrink lockless, the memcg slab shrink is handled in the subsequent patch. [1]. https://lore.kernel.org/lkml/20191129214541.3110-1-ptikhomirov@virtuozzo.com/ [2]. https://lore.kernel.org/all/1437080113.3596.2.camel@stgolabs.net/ [3]. https://lore.kernel.org/lkml/1510609063-3327-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp/ [4]. https://lore.kernel.org/lkml/153365347929.19074.12509495712735843805.stgit@localhost.localdomain/ [5]. https://lore.kernel.org/lkml/20210927074823.5825-1-sultan@kerneltoast.com/ Link: https://lkml.kernel.org/r/20230313112819.38938-3-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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42c9db39 |
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13-Mar-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: vmscan: add a map_nr_max field to shrinker_info Patch series "make slab shrink lockless", v5. This patch series aims to make slab shrink lockless. 1. Background ============= On our servers, we often find the following system cpu hotspots: 52.22% [kernel] [k] down_read_trylock 19.60% [kernel] [k] up_read 8.86% [kernel] [k] shrink_slab 2.44% [kernel] [k] idr_find 1.25% [kernel] [k] count_shadow_nodes 1.18% [kernel] [k] shrink lruvec 0.71% [kernel] [k] mem_cgroup_iter 0.71% [kernel] [k] shrink_node 0.55% [kernel] [k] find_next_bit And we used bpftrace to capture its calltrace as follows: @[ down_read_trylock+1 shrink_slab+128 shrink_node+371 do_try_to_free_pages+232 try_to_free_pages+243 _alloc_pages_slowpath+771 _alloc_pages_nodemask+702 pagecache_get_page+255 filemap_fault+1361 ext4_filemap_fault+44 __do_fault+76 handle_mm_fault+3543 do_user_addr_fault+442 do_page_fault+48 page_fault+62 ]: 1161690 @[ down_read_trylock+1 shrink_slab+128 shrink_node+371 balance_pgdat+690 kswapd+389 kthread+246 ret_from_fork+31 ]: 8424884 @[ down_read_trylock+1 shrink_slab+128 shrink_node+371 do_try_to_free_pages+232 try_to_free_pages+243 __alloc_pages_slowpath+771 __alloc_pages_nodemask+702 __do_page_cache_readahead+244 filemap_fault+1674 ext4_filemap_fault+44 __do_fault+76 handle_mm_fault+3543 do_user_addr_fault+442 do_page_fault+48 page_fault+62 ]: 20917631 We can see that down_read_trylock() of shrinker_rwsem is being called with high frequency at that time. Because of the poor multicore scalability of atomic operations, this can lead to a significant drop in IPC (instructions per cycle). And more, the shrinker_rwsem is a global read-write lock in shrinkers subsystem, which protects most operations such as slab shrink, registration and unregistration of shrinkers, etc. This can easily cause problems in the following cases. 1) When the memory pressure is high and there are many filesystems mounted or unmounted at the same time, slab shrink will be affected (down_read_trylock() failed). Such as the real workload mentioned by Kirill Tkhai: ``` One of the real workloads from my experience is start of an overcommitted node containing many starting containers after node crash (or many resuming containers after reboot for kernel update). In these cases memory pressure is huge, and the node goes round in long reclaim. ``` 2) If a shrinker is blocked (such as the case mentioned in [1]) and a writer comes in (such as mount a fs), then this writer will be blocked and cause all subsequent shrinker-related operations to be blocked. [1]. https://lore.kernel.org/lkml/20191129214541.3110-1-ptikhomirov@virtuozzo.com/ All the above cases can be solved by replacing the shrinker_rwsem trylocks with SRCU. 2. Survey ========= Before doing the code implementation, I found that there were many similar submissions in the community: a. Davidlohr Bueso submitted a patch in 2015. Subject: [PATCH -next v2] mm: srcu-ify shrinkers Link: https://lore.kernel.org/all/1437080113.3596.2.camel@stgolabs.net/ Result: It was finally merged into the linux-next branch, but failed on arm allnoconfig (without CONFIG_SRCU) b. Tetsuo Handa submitted a patchset in 2017. Subject: [PATCH 1/2] mm,vmscan: Kill global shrinker lock. Link: https://lore.kernel.org/lkml/1510609063-3327-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp/ Result: Finally chose to use the current simple way (break when rwsem_is_contended()). And Christoph Hellwig suggested to using SRCU, but SRCU was not unconditionally enabled at the time. c. Kirill Tkhai submitted a patchset in 2018. Subject: [PATCH RFC 00/10] Introduce lockless shrink_slab() Link: https://lore.kernel.org/lkml/153365347929.19074.12509495712735843805.stgit@localhost.localdomain/ Result: At that time, SRCU was not unconditionally enabled, and there were some objections to enabling SRCU. Later, because Kirill's focus was moved to other things, this patchset was not continued to be updated. d. Sultan Alsawaf submitted a patch in 2021. Subject: [PATCH] mm: vmscan: Replace shrinker_rwsem trylocks with SRCU protection Link: https://lore.kernel.org/lkml/20210927074823.5825-1-sultan@kerneltoast.com/ Result: Rejected because SRCU was not unconditionally enabled. We can find that almost all these historical commits were abandoned because SRCU was not unconditionally enabled. But now SRCU has been unconditionally enable by Paul E. McKenney in 2023 [2], so it's time to replace shrinker_rwsem trylocks with SRCU. [2] https://lore.kernel.org/lkml/20230105003759.GA1769545@paulmck-ThinkPad-P17-Gen-1/ 3. Reproduction and testing =========================== We can reproduce the down_read_trylock() hotspot through the following script: ``` #!/bin/bash DIR="/root/shrinker/memcg/mnt" do_create() { mkdir -p /sys/fs/cgroup/memory/test mkdir -p /sys/fs/cgroup/perf_event/test echo 4G > /sys/fs/cgroup/memory/test/memory.limit_in_bytes for i in `seq 0 $1`; do mkdir -p /sys/fs/cgroup/memory/test/$i; echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs; echo $$ > /sys/fs/cgroup/perf_event/test/cgroup.procs; mkdir -p $DIR/$i; done } do_mount() { for i in `seq $1 $2`; do mount -t tmpfs $i $DIR/$i; done } do_touch() { for i in `seq $1 $2`; do echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs; echo $$ > /sys/fs/cgroup/perf_event/test/cgroup.procs; dd if=/dev/zero of=$DIR/$i/file$i bs=1M count=1 & done } case "$1" in touch) do_touch $2 $3 ;; test) do_create 4000 do_mount 0 4000 do_touch 0 3000 ;; *) exit 1 ;; esac ``` Save the above script, then run test and touch commands. Then we can use the following perf command to view hotspots: perf top -U -F 999 1) Before applying this patchset: 32.31% [kernel] [k] down_read_trylock 19.40% [kernel] [k] pv_native_safe_halt 16.24% [kernel] [k] up_read 15.70% [kernel] [k] shrink_slab 4.69% [kernel] [k] _find_next_bit 2.62% [kernel] [k] shrink_node 1.78% [kernel] [k] shrink_lruvec 0.76% [kernel] [k] do_shrink_slab 2) After applying this patchset: 27.83% [kernel] [k] _find_next_bit 16.97% [kernel] [k] shrink_slab 15.82% [kernel] [k] pv_native_safe_halt 9.58% [kernel] [k] shrink_node 8.31% [kernel] [k] shrink_lruvec 5.64% [kernel] [k] do_shrink_slab 3.88% [kernel] [k] mem_cgroup_iter At the same time, we use the following perf command to capture IPC information: perf stat -e cycles,instructions -G test -a --repeat 5 -- sleep 10 1) Before applying this patchset: Performance counter stats for 'system wide' (5 runs): 454187219766 cycles test ( +- 1.84% ) 78896433101 instructions test # 0.17 insn per cycle ( +- 0.44% ) 10.0020430 +- 0.0000366 seconds time elapsed ( +- 0.00% ) 2) After applying this patchset: Performance counter stats for 'system wide' (5 runs): 841954709443 cycles test ( +- 15.80% ) (98.69%) 527258677936 instructions test # 0.63 insn per cycle ( +- 15.11% ) (98.68%) 10.01064 +- 0.00831 seconds time elapsed ( +- 0.08% ) We can see that IPC drops very seriously when calling down_read_trylock() at high frequency. After using SRCU, the IPC is at a normal level. This patch (of 8): To prepare for the subsequent lockless memcg slab shrink, add a map_nr_max field to struct shrinker_info to records its own real shrinker_nr_max. Link: https://lkml.kernel.org/r/20230313112819.38938-1-zhengqi.arch@bytedance.com Link: https://lkml.kernel.org/r/20230313112819.38938-2-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Suggested-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <tkhai@ya.ru> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christian König <christian.koenig@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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32d32ef1 |
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13-Feb-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: improve design doc This patch improves the design doc. Specifically, 1. add a section for the per-memcg mm_struct list, and 2. add a section for the PID controller. Link: https://lkml.kernel.org/r/20230214035445.1250139-2-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9a52b2f3 |
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13-Feb-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: clean up sysfs code This patch cleans up the sysfs code. Specifically, 1. use sysfs_emit(), 2. use __ATTR_RW(), and 3. constify multi-gen LRU struct attribute_group. Link: https://lkml.kernel.org/r/20230214035445.1250139-1-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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54e6842d |
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10-Mar-2023 |
Mike Christie <michael.christie@oracle.com> |
fork/vm: Move common PF_IO_WORKER behavior to new flag This adds a new flag, PF_USER_WORKER, that's used for behavior common to to both PF_IO_WORKER and users like vhost which will use a new helper instead of create_io_thread because they require different behavior for operations like signal handling. The common behavior PF_USER_WORKER covers is the vm reclaim handling. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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be2d5756 |
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15-Feb-2023 |
Baolin Wang <baolin.wang@linux.alibaba.com> |
mm: change to return bool for folio_isolate_lru() Patch series "Change the return value for page isolation functions", v3. Now the page isolation functions did not return a boolean to indicate success or not, instead it will return a negative error when failed to isolate a page. So below code used in most places seem a boolean success/failure thing, which can confuse people whether the isolation is successful. if (folio_isolate_lru(folio)) continue; Moreover the page isolation functions only return 0 or -EBUSY, and most users did not care about the negative error except for few users, thus we can convert all page isolation functions to return a boolean value, which can remove the confusion to make code more clear. No functional changes intended in this patch series. This patch (of 4): Now the folio_isolate_lru() did not return a boolean value to indicate isolation success or not, however below code checking the return value can make people think that it was a boolean success/failure thing, which makes people easy to make mistakes (see the fix patch[1]). if (folio_isolate_lru(folio)) continue; Thus it's better to check the negative error value expilictly returned by folio_isolate_lru(), which makes code more clear per Linus's suggestion[2]. Moreover Matthew suggested we can convert the isolation functions to return a boolean[3], since most users did not care about the negative error value, and can also remove the confusing of checking return value. So this patch converts the folio_isolate_lru() to return a boolean value, which means return 'true' to indicate the folio isolation is successful, and 'false' means a failure to isolation. Meanwhile changing all users' logic of checking the isolation state. No functional changes intended. [1] https://lore.kernel.org/all/20230131063206.28820-1-Kuan-Ying.Lee@mediatek.com/T/#u [2] https://lore.kernel.org/all/CAHk-=wiBrY+O-4=2mrbVyxR+hOqfdJ=Do6xoucfJ9_5az01L4Q@mail.gmail.com/ [3] https://lore.kernel.org/all/Y+sTFqwMNAjDvxw3@casper.infradead.org/ Link: https://lkml.kernel.org/r/cover.1676424378.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/8a4e3679ed4196168efadf7ea36c038f2f7d5aa9.1676424378.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: SeongJae Park <sj@kernel.org> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f7a449f7 |
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13-Feb-2023 |
Roman Gushchin <roman.gushchin@linux.dev> |
mm: memcontrol: rename memcg_kmem_enabled() Currently there are two kmem-related helper functions with a confusing semantics: memcg_kmem_enabled() and mem_cgroup_kmem_disabled(). The problem is that an obvious expectation memcg_kmem_enabled() == !mem_cgroup_kmem_disabled(), can be false. mem_cgroup_kmem_disabled() is similar to mem_cgroup_disabled(): it returns true only if CONFIG_MEMCG_KMEM is not set or the kmem accounting is disabled using a boot time kernel option "cgroup.memory=nokmem". It never changes the value dynamically. memcg_kmem_enabled() is different: it always returns false until the first non-root memory cgroup will get online (assuming the kernel memory accounting is enabled). It's goal is to improve the performance on systems without the cgroupfs mounted/memory controller enabled or on the systems with only the root memory cgroup. To make things more obvious and avoid potential bugs, let's rename memcg_kmem_enabled() to memcg_kmem_online(). Link: https://lkml.kernel.org/r/20230213192922.1146370-1-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9f550d78 |
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13-Feb-2023 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: avoid futile retries Recall that the per-node memcg LRU has two generations and they alternate when the last memcg (of a given node) is moved from one to the other. Each generation is also sharded into multiple bins to improve scalability. A reclaimer starts with a random bin (in the old generation) and, if it fails, it will retry, i.e., to try the rest of the bins. If a reclaimer fails with the last memcg, it should move this memcg to the young generation first, which causes the generations to alternate, and then retry. Otherwise, the retries will be futile because all other bins are empty. Link: https://lkml.kernel.org/r/20230213075322.1416966-1-yuzhao@google.com Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: T.J. Mercier <tjmercier@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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abf08672 |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: simplify lru_gen_look_around() Update the folio generation in place with or without current->reclaim_state->mm_walk. The LRU lock is held for longer, if mm_walk is NULL and the number of folios to update is more than PAGEVEC_SIZE. This causes a measurable regression from the LRU lock contention during a microbencmark. But a tiny regression is not worth the complexity. Link: https://lkml.kernel.org/r/20230118001827.1040870-8-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b5ff4133 |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: improve walk_pmd_range() Improve readability of walk_pmd_range() and walk_pmd_range_locked(). Link: https://lkml.kernel.org/r/20230118001827.1040870-7-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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37cc9997 |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: improve lru_gen_exit_memcg() Add warnings and poison ->next. Link: https://lkml.kernel.org/r/20230118001827.1040870-6-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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36c7b4db |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: section for memcg LRU Move memcg LRU code into a dedicated section. Improve the design doc to outline its architecture. Link: https://lkml.kernel.org/r/20230118001827.1040870-5-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ccbbbb85 |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: section for Bloom filters Move Bloom filters code into a dedicated section. Improve the design doc to explain Bloom filter usage and connection between aging and eviction in their use. Link: https://lkml.kernel.org/r/20230118001827.1040870-4-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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db19a43d |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: section for rmap/PT walk feedback Add a section for lru_gen_look_around() in the code and the design doc. Link: https://lkml.kernel.org/r/20230118001827.1040870-3-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7b8144e6 |
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17-Jan-2023 |
T.J. Alumbaugh <talumbau@google.com> |
mm: multi-gen LRU: section for working set protection Patch series "mm: multi-gen LRU: improve". This patch series improves a few MGLRU functions, collects related functions, and adds additional documentation. This patch (of 7): Add a section for working set protection in the code and the design doc. The admin doc already contains its usage. Link: https://lkml.kernel.org/r/20230118001827.1040870-1-talumbau@google.com Link: https://lkml.kernel.org/r/20230118001827.1040870-2-talumbau@google.com Signed-off-by: T.J. Alumbaugh <talumbau@google.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8788f678 |
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30-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: add vma_has_recency() Add vma_has_recency() to indicate whether a VMA may exhibit temporal locality that the LRU algorithm relies on. This function returns false for VMAs marked by VM_SEQ_READ or VM_RAND_READ. While the former flag indicates linear access, i.e., a special case of spatial locality, both flags indicate a lack of temporal locality, i.e., the reuse of an area within a relatively small duration. "Recency" is chosen over "locality" to avoid confusion between temporal and spatial localities. Before this patch, the active/inactive LRU only ignored the accessed bit from VMAs marked by VM_SEQ_READ. After this patch, the active/inactive LRU and MGLRU share the same logic: they both ignore the accessed bit if vma_has_recency() returns false. For the active/inactive LRU, the following fio test showed a [6, 8]% increase in IOPS when randomly accessing mapped files under memory pressure. kb=$(awk '/MemTotal/ { print $2 }' /proc/meminfo) kb=$((kb - 8*1024*1024)) modprobe brd rd_nr=1 rd_size=$kb dd if=/dev/zero of=/dev/ram0 bs=1M mkfs.ext4 /dev/ram0 mount /dev/ram0 /mnt/ swapoff -a fio --name=test --directory=/mnt/ --ioengine=mmap --numjobs=8 \ --size=8G --rw=randrw --time_based --runtime=10m \ --group_reporting The discussion that led to this patch is here [1]. Additional test results are available in that thread. [1] https://lore.kernel.org/r/Y31s%2FK8T85jh05wH@google.com/ Link: https://lkml.kernel.org/r/20221230215252.2628425-1-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Righi <andrea.righi@canonical.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michael Larabel <Michael@MichaelLarabel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f386e931 |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: simplify arch_has_hw_pte_young() check Scanning page tables when hardware does not set the accessed bit has no real use cases. Link: https://lkml.kernel.org/r/20221222041905.2431096-9-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e9d4e1ee |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: clarify scan_control flags Among the flags in scan_control: 1. sc->may_swap, which indicates swap constraint due to memsw.max, is supported as usual. 2. sc->proactive, which indicates reclaim by memory.reclaim, may not opportunistically skip the aging path, since it is considered less latency sensitive. 3. !(sc->gfp_mask & __GFP_IO), which indicates IO constraint, lowers swappiness to prioritize file LRU, since clean file folios are more likely to exist. 4. sc->may_writepage and sc->may_unmap, which indicates opportunistic reclaim, are rejected, since unmapped clean folios are already prioritized. Scanning for more of them is likely futile and can cause high reclaim latency when there is a large number of memcgs. The rest are handled by the existing code. Link: https://lkml.kernel.org/r/20221222041905.2431096-8-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e4dde56c |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: per-node lru_gen_folio lists For each node, memcgs are divided into two generations: the old and the young. For each generation, memcgs are randomly sharded into multiple bins to improve scalability. For each bin, an RCU hlist_nulls is virtually divided into three segments: the head, the tail and the default. An onlining memcg is added to the tail of a random bin in the old generation. The eviction starts at the head of a random bin in the old generation. The per-node memcg generation counter, whose reminder (mod 2) indexes the old generation, is incremented when all its bins become empty. There are four operations: 1. MEMCG_LRU_HEAD, which moves an memcg to the head of a random bin in its current generation (old or young) and updates its "seg" to "head"; 2. MEMCG_LRU_TAIL, which moves an memcg to the tail of a random bin in its current generation (old or young) and updates its "seg" to "tail"; 3. MEMCG_LRU_OLD, which moves an memcg to the head of a random bin in the old generation, updates its "gen" to "old" and resets its "seg" to "default"; 4. MEMCG_LRU_YOUNG, which moves an memcg to the tail of a random bin in the young generation, updates its "gen" to "young" and resets its "seg" to "default". The events that trigger the above operations are: 1. Exceeding the soft limit, which triggers MEMCG_LRU_HEAD; 2. The first attempt to reclaim an memcg below low, which triggers MEMCG_LRU_TAIL; 3. The first attempt to reclaim an memcg below reclaimable size threshold, which triggers MEMCG_LRU_TAIL; 4. The second attempt to reclaim an memcg below reclaimable size threshold, which triggers MEMCG_LRU_YOUNG; 5. Attempting to reclaim an memcg below min, which triggers MEMCG_LRU_YOUNG; 6. Finishing the aging on the eviction path, which triggers MEMCG_LRU_YOUNG; 7. Offlining an memcg, which triggers MEMCG_LRU_OLD. Note that memcg LRU only applies to global reclaim, and the round-robin incrementing of their max_seq counters ensures the eventual fairness to all eligible memcgs. For memcg reclaim, it still relies on mem_cgroup_iter(). Link: https://lkml.kernel.org/r/20221222041905.2431096-7-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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77d4459a |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: shuffle should_run_aging() Move should_run_aging() next to its only caller left. Link: https://lkml.kernel.org/r/20221222041905.2431096-6-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7348cc91 |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: remove aging fairness safeguard Recall that the aging produces the youngest generation: first it scans for accessed folios and updates their gen counters; then it increments lrugen->max_seq. The current aging fairness safeguard for kswapd uses two passes to ensure the fairness to multiple eligible memcgs. On the first pass, which is shared with the eviction, it checks whether all eligible memcgs are low on cold folios. If so, it requires a second pass, on which it ages all those memcgs at the same time. With memcg LRU, the aging, while ensuring eventual fairness, will run when necessary. Therefore the current aging fairness safeguard for kswapd will not be needed. Note that memcg LRU only applies to global reclaim. For memcg reclaim, the aging can be unfair to different memcgs, i.e., their lrugen->max_seq can be incremented at different paces. Link: https://lkml.kernel.org/r/20221222041905.2431096-5-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a579086c |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: remove eviction fairness safeguard Recall that the eviction consumes the oldest generation: first it bucket-sorts folios whose gen counters were updated by the aging and reclaims the rest; then it increments lrugen->min_seq. The current eviction fairness safeguard for global reclaim has a dilemma: when there are multiple eligible memcgs, should it continue or stop upon meeting the reclaim goal? If it continues, it overshoots and increases direct reclaim latency; if it stops, it loses fairness between memcgs it has taken memory away from and those it has yet to. With memcg LRU, the eviction, while ensuring eventual fairness, will stop upon meeting its goal. Therefore the current eviction fairness safeguard for global reclaim will not be needed. Note that memcg LRU only applies to global reclaim. For memcg reclaim, the eviction will continue, even if it is overshooting. This becomes unconditional due to code simplification. Link: https://lkml.kernel.org/r/20221222041905.2431096-4-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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6df1b221 |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: rename lrugen->lists[] to lrugen->folios[] lru_gen_folio will be chained into per-node lists by the coming lrugen->list. Link: https://lkml.kernel.org/r/20221222041905.2431096-3-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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391655fe |
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21-Dec-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: rename lru_gen_struct to lru_gen_folio Patch series "mm: multi-gen LRU: memcg LRU", v3. Overview ======== An memcg LRU is a per-node LRU of memcgs. It is also an LRU of LRUs, since each node and memcg combination has an LRU of folios (see mem_cgroup_lruvec()). Its goal is to improve the scalability of global reclaim, which is critical to system-wide memory overcommit in data centers. Note that memcg reclaim is currently out of scope. Its memory bloat is a pointer to each lruvec and negligible to each pglist_data. In terms of traversing memcgs during global reclaim, it improves the best-case complexity from O(n) to O(1) and does not affect the worst-case complexity O(n). Therefore, on average, it has a sublinear complexity in contrast to the current linear complexity. The basic structure of an memcg LRU can be understood by an analogy to the active/inactive LRU (of folios): 1. It has the young and the old (generations), i.e., the counterparts to the active and the inactive; 2. The increment of max_seq triggers promotion, i.e., the counterpart to activation; 3. Other events trigger similar operations, e.g., offlining an memcg triggers demotion, i.e., the counterpart to deactivation. In terms of global reclaim, it has two distinct features: 1. Sharding, which allows each thread to start at a random memcg (in the old generation) and improves parallelism; 2. Eventual fairness, which allows direct reclaim to bail out at will and reduces latency without affecting fairness over some time. The commit message in patch 6 details the workflow: https://lore.kernel.org/r/20221222041905.2431096-7-yuzhao@google.com/ The following is a simple test to quickly verify its effectiveness. Test design: 1. Create multiple memcgs. 2. Each memcg contains a job (fio). 3. All jobs access the same amount of memory randomly. 4. The system does not experience global memory pressure. 5. Periodically write to the root memory.reclaim. Desired outcome: 1. All memcgs have similar pgsteal counts, i.e., stddev(pgsteal) over mean(pgsteal) is close to 0%. 2. The total pgsteal is close to the total requested through memory.reclaim, i.e., sum(pgsteal) over sum(requested) is close to 100%. Actual outcome [1]: MGLRU off MGLRU on stddev(pgsteal) / mean(pgsteal) 75% 20% sum(pgsteal) / sum(requested) 425% 95% #################################################################### MEMCGS=128 for ((memcg = 0; memcg < $MEMCGS; memcg++)); do mkdir /sys/fs/cgroup/memcg$memcg done start() { echo $BASHPID > /sys/fs/cgroup/memcg$memcg/cgroup.procs fio -name=memcg$memcg --numjobs=1 --ioengine=mmap \ --filename=/dev/zero --size=1920M --rw=randrw \ --rate=64m,64m --random_distribution=random \ --fadvise_hint=0 --time_based --runtime=10h \ --group_reporting --minimal } for ((memcg = 0; memcg < $MEMCGS; memcg++)); do start & done sleep 600 for ((i = 0; i < 600; i++)); do echo 256m >/sys/fs/cgroup/memory.reclaim sleep 6 done for ((memcg = 0; memcg < $MEMCGS; memcg++)); do grep "pgsteal " /sys/fs/cgroup/memcg$memcg/memory.stat done #################################################################### [1]: This was obtained from running the above script (touches less than 256GB memory) on an EPYC 7B13 with 512GB DRAM for over an hour. This patch (of 8): The new name lru_gen_folio will be more distinct from the coming lru_gen_memcg. Link: https://lkml.kernel.org/r/20221222041905.2431096-1-yuzhao@google.com Link: https://lkml.kernel.org/r/20221222041905.2431096-2-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5a9e3474 |
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21-Dec-2022 |
Vishal Moola (Oracle) <vishal.moola@gmail.com> |
mm/swap: convert deactivate_page() to folio_deactivate() Deactivate_page() has already been converted to use folios, this change converts it to take in a folio argument instead of calling page_folio(). It also renames the function folio_deactivate() to be more consistent with other folio functions. [akpm@linux-foundation.org: fix left-over comments, per Yu Zhao] Link: https://lkml.kernel.org/r/20221221180848.20774-5-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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badc28d4 |
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02-Feb-2023 |
Qi Zheng <zhengqi.arch@bytedance.com> |
mm: shrinkers: fix deadlock in shrinker debugfs The debugfs_remove_recursive() is invoked by unregister_shrinker(), which is holding the write lock of shrinker_rwsem. It will waits for the handler of debugfs file complete. The handler also needs to hold the read lock of shrinker_rwsem to do something. So it may cause the following deadlock: CPU0 CPU1 debugfs_file_get() shrinker_debugfs_count_show()/shrinker_debugfs_scan_write() unregister_shrinker() --> down_write(&shrinker_rwsem); debugfs_remove_recursive() // wait for (A) --> wait_for_completion(); // wait for (B) --> down_read_killable(&shrinker_rwsem) debugfs_file_put() -- (A) up_write() -- (B) The down_read_killable() can be killed, so that the above deadlock can be recovered. But it still requires an extra kill action, otherwise it will block all subsequent shrinker-related operations, so it's better to fix it. [akpm@linux-foundation.org: fix CONFIG_SHRINKER_DEBUG=n stub] Link: https://lkml.kernel.org/r/20230202105612.64641-1-zhengqi.arch@bytedance.com Fixes: 5035ebc644ae ("mm: shrinkers: introduce debugfs interface for memory shrinkers") Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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de08eaa6 |
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15-Jan-2023 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: fix crash during cgroup migration lru_gen_migrate_mm() assumes lru_gen_add_mm() runs prior to itself. This isn't true for the following scenario: CPU 1 CPU 2 clone() cgroup_can_fork() cgroup_procs_write() cgroup_post_fork() task_lock() lru_gen_migrate_mm() task_unlock() task_lock() lru_gen_add_mm() task_unlock() And when the above happens, kernel crashes because of linked list corruption (mm_struct->lru_gen.list). Link: https://lore.kernel.org/r/20230115134651.30028-1-msizanoen@qtmlabs.xyz/ Link: https://lkml.kernel.org/r/20230116034405.2960276-1-yuzhao@google.com Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: msizanoen <msizanoen@qtmlabs.xyz> Tested-by: msizanoen <msizanoen@qtmlabs.xyz> Cc: <stable@vger.kernel.org> [6.1+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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55ab834a |
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16-Dec-2022 |
Michal Hocko <mhocko@suse.com> |
Revert "mm: add nodes= arg to memory.reclaim" This reverts commit 12a5d3955227b0d7e04fb793ccceeb2a1dd275c5. Although it is recognized that a finer grained pro-active reclaim is something we need and want the semantic of this implementation is really ambiguous. In a follow up discussion it became clear that there are two essential usecases here. One is to use memory.reclaim to pro-actively reclaim memory and expectation is that the requested and reported amount of memory is uncharged from the memcg. Another usecase focuses on pro-active demotion when the memory is merely shuffled around to demotion targets while the overall charged memory stays unchanged. The current implementation considers demoted pages as reclaimed and that break both usecases. [1] has tried to address the reporting part but there are more issues with that summarized in [2] and follow up emails. Let's revert the nodemask based extension of the memcg pro-active reclaim for now until we settle with a more robust semantic. [1] http://lkml.kernel.org/r/http://lkml.kernel.org/r/20221206023406.3182800-1-almasrymina@google.com [2] http://lkml.kernel.org/r/Y5bsmpCyeryu3Zz1@dhcp22.suse.cz Link: https://lkml.kernel.org/r/Y5xASNe1x8cusiTx@dhcp22.suse.cz Fixes: 12a5d3955227b0d ("mm: add nodes= arg to memory.reclaim") Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: zefan li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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eb780dca |
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21-Oct-2022 |
Peter Zijlstra <peterz@infradead.org> |
mm: Remove pointless barrier() after pmdp_get_lockless() pmdp_get_lockless() should itself imply any ordering required. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20221022114425.298833095%40infradead.org
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dab6e717 |
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26-Nov-2020 |
Peter Zijlstra <peterz@infradead.org> |
mm: Rename pmd_read_atomic() There's no point in having the identical routines for PTE/PMD have different names. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20221022114424.841277397%40infradead.org
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c449deb2 |
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04-Dec-2022 |
Hugh Dickins <hughd@google.com> |
mm: memcg: fix swapcached stat accounting I'd been worried by high "swapcached" counts in memcg OOM reports, thought we had a problem freeing swapcache, but it was just the accounting that was wrong. Two issues: 1. When __remove_mapping() removes swapcache, __delete_from_swap_cache() relies on memcg_data for the right counts to be updated; but that had already been reset by mem_cgroup_swapout(). Swap those calls around - mem_cgroup_swapout() does not require the swapcached flag to be set. 6.1 commit ac35a4902374 ("mm: multi-gen LRU: minimal implementation") already made a similar swap for workingset_eviction(), but not for this. 2. memcg's "swapcached" count was added for memcg v2 stats, but displayed on OOM even for memcg v1: so mem_cgroup_move_account() ought to move it. Link: https://lkml.kernel.org/r/b8b96ee0-1e1e-85f8-df97-c82a11d7cd14@google.com Fixes: b6038942480e ("mm: memcg: add swapcache stat for memcg v2") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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12a5d395 |
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02-Dec-2022 |
Mina Almasry <almasrymina@google.com> |
mm: add nodes= arg to memory.reclaim The nodes= arg instructs the kernel to only scan the given nodes for proactive reclaim. For example use cases, consider a 2 tier memory system: nodes 0,1 -> top tier nodes 2,3 -> second tier $ echo "1m nodes=0" > memory.reclaim This instructs the kernel to attempt to reclaim 1m memory from node 0. Since node 0 is a top tier node, demotion will be attempted first. This is useful to direct proactive reclaim to specific nodes that are under pressure. $ echo "1m nodes=2,3" > memory.reclaim This instructs the kernel to attempt to reclaim 1m memory in the second tier, since this tier of memory has no demotion targets the memory will be reclaimed. $ echo "1m nodes=0,1" > memory.reclaim Instructs the kernel to reclaim memory from the top tier nodes, which can be desirable according to the userspace policy if there is pressure on the top tiers. Since these nodes have demotion targets, the kernel will attempt demotion first. Since commit 3f1509c57b1b ("Revert "mm/vmscan: never demote for memcg reclaim""), the proactive reclaim interface memory.reclaim does both reclaim and demotion. Reclaim and demotion incur different latency costs to the jobs in the cgroup. Demoted memory would still be addressable by the userspace at a higher latency, but reclaimed memory would need to incur a pagefault. The 'nodes' arg is useful to allow the userspace to control demotion and reclaim independently according to its policy: if the memory.reclaim is called on a node with demotion targets, it will attempt demotion first; if it is called on a node without demotion targets, it will only attempt reclaim. Link: https://lkml.kernel.org/r/20221202223533.1785418-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Muchun Song <songmuchun@bytedance.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Tejun Heo <tj@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: zefan li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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6b426d07 |
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01-Dec-2022 |
Mina Almasry <almasrymina@google.com> |
mm: disable top-tier fallback to reclaim on proactive reclaim Reclaiming directly from top tier nodes breaks the aging pipeline of memory tiers. If we have a RAM -> CXL -> storage hierarchy, we should demote from RAM to CXL and from CXL to storage. If we reclaim a page from RAM, it means we 'demote' it directly from RAM to storage, bypassing potentially a huge amount of pages colder than it in CXL. However disabling reclaim from top tier nodes entirely would cause ooms in edge scenarios where lower tier memory is unreclaimable for whatever reason, e.g. memory being mlocked() or too hot to reclaim. In these cases we would rather the job run with a performance regression rather than it oom altogether. However, we can disable reclaim from top tier nodes for proactive reclaim. That reclaim is not real memory pressure, and we don't have any cause to be breaking the aging pipeline. [akpm@linux-foundation.org: restore comment layout, per Ying Huang] Link: https://lkml.kernel.org/r/20221201233317.1394958-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Greg Thelen <gthelen@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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adb82130 |
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01-Dec-2022 |
Yosry Ahmed <yosryahmed@google.com> |
mm: memcg: fix stale protection of reclaim target memcg Patch series "mm: memcg: fix protection of reclaim target memcg", v3. This series fixes a bug in calculating the protection of the reclaim target memcg where we end up using stale effective protection values from the last reclaim operation, instead of completely ignoring the protection of the reclaim target as intended. More detailed explanation and examples in patch 1, which includes the fix. Patches 2 & 3 introduce a selftest case that catches the bug. This patch (of 3): When we are doing memcg reclaim, the intended behavior is that we ignore any protection (memory.min, memory.low) of the target memcg (but not its children). Ever since the patch pointed to by the "Fixes" tag, we actually read a stale value for the target memcg protection when deciding whether to skip the memcg or not because it is protected. If the stale value happens to be high enough, we don't reclaim from the target memcg. Essentially, in some cases we may falsely skip reclaiming from the target memcg of reclaim because we read a stale protection value from last time we reclaimed from it. During reclaim, mem_cgroup_calculate_protection() is used to determine the effective protection (emin and elow) values of a memcg. The protection of the reclaim target is ignored, but we cannot set their effective protection to 0 due to a limitation of the current implementation (see comment in mem_cgroup_protection()). Instead, we leave their effective protection values unchaged, and later ignore it in mem_cgroup_protection(). However, mem_cgroup_protection() is called later in shrink_lruvec()->get_scan_count(), which is after the mem_cgroup_below_{min/low}() checks in shrink_node_memcgs(). As a result, the stale effective protection values of the target memcg may lead us to skip reclaiming from the target memcg entirely, before calling shrink_lruvec(). This can be even worse with recursive protection, where the stale target memcg protection can be higher than its standalone protection. See two examples below (a similar version of example (a) is added to test_memcontrol in a later patch). (a) A simple example with proactive reclaim is as follows. Consider the following hierarchy: ROOT | A | B (memory.min = 10M) Consider the following scenario: - B has memory.current = 10M. - The system undergoes global reclaim (or memcg reclaim in A). - In shrink_node_memcgs(): - mem_cgroup_calculate_protection() calculates the effective min (emin) of B as 10M. - mem_cgroup_below_min() returns true for B, we do not reclaim from B. - Now if we want to reclaim 5M from B using proactive reclaim (memory.reclaim), we should be able to, as the protection of the target memcg should be ignored. - In shrink_node_memcgs(): - mem_cgroup_calculate_protection() immediately returns for B without doing anything, as B is the target memcg, relying on mem_cgroup_protection() to ignore B's stale effective min (still 10M). - mem_cgroup_below_min() reads the stale effective min for B and we skip it instead of ignoring its protection as intended, as we never reach mem_cgroup_protection(). (b) An more complex example with recursive protection is as follows. Consider the following hierarchy with memory_recursiveprot: ROOT | A (memory.min = 50M) | B (memory.min = 10M, memory.high = 40M) Consider the following scenario: - B has memory.current = 35M. - The system undergoes global reclaim (target memcg is NULL). - B will have an effective min of 50M (all of A's unclaimed protection). - B will not be reclaimed from. - Now allocate 10M more memory in B, pushing it above it's high limit. - The system undergoes memcg reclaim from B (target memcg is B). - Like example (a), we do nothing in mem_cgroup_calculate_protection(), then call mem_cgroup_below_min(), which will read the stale effective min for B (50M) and skip it. In this case, it's even worse because we are not just considering B's standalone protection (10M), but we are reading a much higher stale protection (50M) which will cause us to not reclaim from B at all. This is an artifact of commit 45c7f7e1ef17 ("mm, memcg: decouple e{low,min} state mutations from protection checks") which made mem_cgroup_calculate_protection() only change the state without returning any value. Before that commit, we used to return MEMCG_PROT_NONE for the target memcg, which would cause us to skip the mem_cgroup_below_{min/low}() checks. After that commit we do not return anything and we end up checking the min & low effective protections for the target memcg, which are stale. Update mem_cgroup_supports_protection() to also check if we are reclaiming from the target, and rename it to mem_cgroup_unprotected() (now returns true if we should not protect the memcg, much simpler logic). Link: https://lkml.kernel.org/r/20221202031512.1365483-1-yosryahmed@google.com Link: https://lkml.kernel.org/r/20221202031512.1365483-2-yosryahmed@google.com Fixes: 45c7f7e1ef17 ("mm, memcg: decouple e{low,min} state mutations from protection checks") Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Chris Down <chris@chrisdown.name> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vasily Averin <vasily.averin@linux.dev> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8ef9c32a |
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24-Nov-2022 |
Xu Panda <xu.panda@zte.com.cn> |
mm: vmscan: use sysfs_emit() to instead of scnprintf() Replace open-coded snprintf() with sysfs_emit() to simplify the code. Link: https://lkml.kernel.org/r/202211241929015476424@zte.com.cn Signed-off-by: Xu Panda <xu.panda@zte.com.cn> Signed-off-by: Yang Yang <yang.yang29@zte.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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931b6a8b |
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15-Nov-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: remove NULL checks on NODE_DATA() NODE_DATA() is preallocated for all possible nodes after commit 09f49dca570a ("mm: handle uninitialized numa nodes gracefully"). Checking its return value against NULL is now unnecessary. Link: https://lkml.kernel.org/r/20221116013808.3995280-2-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e83b39d6 |
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15-Nov-2022 |
Jan Kara <jack@suse.cz> |
mm: make drop_caches keep reclaiming on all nodes Currently, drop_caches are reclaiming node-by-node, looping on each node until reclaim could not make progress. This can however leave quite some slab entries (such as filesystem inodes) unreclaimed if objects say on node 1 keep objects on node 0 pinned. So move the "loop until no progress" loop to the node-by-node iteration to retry reclaim also on other nodes if reclaim on some nodes made progress. This fixes problem when drop_caches was not reclaiming lots of otherwise perfectly fine to reclaim inodes. Link: https://lkml.kernel.org/r/20221115123255.12559-1-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: You Zhou <you.zhou@intel.com> Reported-by: Pengfei Xu <pengfei.xu@intel.com> Tested-by: Pengfei Xu <pengfei.xu@intel.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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57e9cc50 |
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26-Oct-2022 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: split khugepaged stats from direct reclaim stats Direct reclaim stats are useful for identifying a potential source for application latency, as well as spotting issues with kswapd. However, khugepaged currently distorts the picture: as a kernel thread it doesn't impose allocation latencies on userspace, and it explicitly opts out of kswapd reclaim. Its activity showing up in the direct reclaim stats is misleading. Counting it as kswapd reclaim could also cause confusion when trying to understand actual kswapd behavior. Break out khugepaged from the direct reclaim counters into new pgsteal_khugepaged, pgdemote_khugepaged, pgscan_khugepaged counters. Test with a huge executable (CONFIG_READ_ONLY_THP_FOR_FS): pgsteal_kswapd 1342185 pgsteal_direct 0 pgsteal_khugepaged 3623 pgscan_kswapd 1345025 pgscan_direct 0 pgscan_khugepaged 3623 Link: https://lkml.kernel.org/r/20221026180133.377671-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Eric Bergen <ebergen@meta.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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0538a82c |
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13-Oct-2022 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: make rotations a secondary factor in balancing anon vs file We noticed a 2% webserver throughput regression after upgrading from 5.6. This could be tracked down to a shift in the anon/file reclaim balance (confirmed with swappiness) that resulted in worse reclaim efficiency and thus more kswapd activity for the same outcome. The change that exposed the problem is aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU"). By qualifying swapins based on their refault distance, it lowered the cost of anon reclaim in this workload, in turn causing (much) more anon scanning than before. Scanning the anon list is more expensive due to the higher ratio of mmapped pages that may rotate during reclaim, and so the result was an increase in %sys time. Right now, rotations aren't considered a cost when balancing scan pressure between LRUs. We can end up with very few file refaults putting all the scan pressure on hot anon pages that are rotated en masse, don't get reclaimed, and never push back on the file LRU again. We still only reclaim file cache in that case, but we burn a lot CPU rotating anon pages. It's "fair" from an LRU age POV, but doesn't reflect the real cost it imposes on the system. Consider rotations as a secondary factor in balancing the LRUs. This doesn't attempt to make a precise comparison between IO cost and CPU cost, it just says: if reloads are about comparable between the lists, or rotations are overwhelmingly different, adjust for CPU work. This fixed the regression on our webservers. It has since been deployed to the entire Meta fleet and hasn't caused any problems. Link: https://lkml.kernel.org/r/20221013193113.726425-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4aaf269c |
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22-Nov-2022 |
Juergen Gross <jgross@suse.com> |
mm: introduce arch_has_hw_nonleaf_pmd_young() When running as a Xen PV guests commit eed9a328aa1a ("mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG") can cause a protection violation in pmdp_test_and_clear_young(): BUG: unable to handle page fault for address: ffff8880083374d0 #PF: supervisor write access in kernel mode #PF: error_code(0x0003) - permissions violation PGD 3026067 P4D 3026067 PUD 3027067 PMD 7fee5067 PTE 8010000008337065 Oops: 0003 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 158 Comm: kswapd0 Not tainted 6.1.0-rc5-20221118-doflr+ #1 RIP: e030:pmdp_test_and_clear_young+0x25/0x40 This happens because the Xen hypervisor can't emulate direct writes to page table entries other than PTEs. This can easily be fixed by introducing arch_has_hw_nonleaf_pmd_young() similar to arch_has_hw_pte_young() and test that instead of CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG. Link: https://lkml.kernel.org/r/20221123064510.16225-1-jgross@suse.com Fixes: eed9a328aa1a ("mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG") Signed-off-by: Juergen Gross <jgross@suse.com> Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Acked-by: Yu Zhao <yuzhao@google.com> Tested-by: Sander Eikelenboom <linux@eikelenboom.it> Acked-by: David Hildenbrand <david@redhat.com> [core changes] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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81a70c21 |
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17-Nov-2022 |
Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> |
mm/cgroup/reclaim: fix dirty pages throttling on cgroup v1 balance_dirty_pages doesn't do the required dirty throttling on cgroupv1. See commit 9badce000e2c ("cgroup, writeback: don't enable cgroup writeback on traditional hierarchies"). Instead, the kernel depends on writeback throttling in shrink_folio_list to achieve the same goal. With large memory systems, the flusher may not be able to writeback quickly enough such that we will start finding pages in the shrink_folio_list already in writeback. Hence for cgroupv1 let's do a reclaim throttle after waking up the flusher. The below test which used to fail on a 256GB system completes till the the file system is full with this change. root@lp2:/sys/fs/cgroup/memory# mkdir test root@lp2:/sys/fs/cgroup/memory# cd test/ root@lp2:/sys/fs/cgroup/memory/test# echo 120M > memory.limit_in_bytes root@lp2:/sys/fs/cgroup/memory/test# echo $$ > tasks root@lp2:/sys/fs/cgroup/memory/test# dd if=/dev/zero of=/home/kvaneesh/test bs=1M Killed Link: https://lkml.kernel.org/r/20221118070603.84081-1-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: zefan li <lizefan.x@bytedance.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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359a5e14 |
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15-Nov-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: retry folios written back while isolated The page reclaim isolates a batch of folios from the tail of one of the LRU lists and works on those folios one by one. For a suitable swap-backed folio, if the swap device is async, it queues that folio for writeback. After the page reclaim finishes an entire batch, it puts back the folios it queued for writeback to the head of the original LRU list. In the meantime, the page writeback flushes the queued folios also by batches. Its batching logic is independent from that of the page reclaim. For each of the folios it writes back, the page writeback calls folio_rotate_reclaimable() which tries to rotate a folio to the tail. folio_rotate_reclaimable() only works for a folio after the page reclaim has put it back. If an async swap device is fast enough, the page writeback can finish with that folio while the page reclaim is still working on the rest of the batch containing it. In this case, that folio will remain at the head and the page reclaim will not retry it before reaching there. This patch adds a retry to evict_folios(). After evict_folios() has finished an entire batch and before it puts back folios it cannot free immediately, it retries those that may have missed the rotation. Before this patch, ~60% of folios swapped to an Intel Optane missed folio_rotate_reclaimable(). After this patch, ~99% of missed folios were reclaimed upon retry. This problem affects relatively slow async swap devices like Samsung 980 Pro much less and does not affect sync swap devices like zram or zswap at all. Link: https://lkml.kernel.org/r/20221116013808.3995280-1-yuzhao@google.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: "Yin, Fengwei" <fengwei.yin@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f53af428 |
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01-Aug-2022 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: fix extreme overreclaim and swap floods During proactive reclaim, we sometimes observe severe overreclaim, with several thousand times more pages reclaimed than requested. This trace was obtained from shrink_lruvec() during such an instance: prio:0 anon_cost:1141521 file_cost:7767 nr_reclaimed:4387406 nr_to_reclaim:1047 (or_factor:4190) nr=[7161123 345 578 1111] While he reclaimer requested 4M, vmscan reclaimed close to 16G, most of it by swapping. These requests take over a minute, during which the write() to memory.reclaim is unkillably stuck inside the kernel. Digging into the source, this is caused by the proportional reclaim bailout logic. This code tries to resolve a fundamental conflict: to reclaim roughly what was requested, while also aging all LRUs fairly and in accordance to their size, swappiness, refault rates etc. The way it attempts fairness is that once the reclaim goal has been reached, it stops scanning the LRUs with the smaller remaining scan targets, and adjusts the remainder of the bigger LRUs according to how much of the smaller LRUs was scanned. It then finishes scanning that remainder regardless of the reclaim goal. This works fine if priority levels are low and the LRU lists are comparable in size. However, in this instance, the cgroup that is targeted by proactive reclaim has almost no files left - they've already been squeezed out by proactive reclaim earlier - and the remaining anon pages are hot. Anon rotations cause the priority level to drop to 0, which results in reclaim targeting all of anon (a lot) and all of file (almost nothing). By the time reclaim decides to bail, it has scanned most or all of the file target, and therefor must also scan most or all of the enormous anon target. This target is thousands of times larger than the reclaim goal, thus causing the overreclaim. The bailout code hasn't changed in years, why is this failing now? The most likely explanations are two other recent changes in anon reclaim: 1. Before the series starting with commit 5df741963d52 ("mm: fix LRU balancing effect of new transparent huge pages"), the VM was overall relatively reluctant to swap at all, even if swap was configured. This means the LRU balancing code didn't come into play as often as it does now, and mostly in high pressure situations where pronounced swap activity wouldn't be as surprising. 2. For historic reasons, shrink_lruvec() loops on the scan targets of all LRU lists except the active anon one, meaning it would bail if the only remaining pages to scan were active anon - even if there were a lot of them. Before the series starting with commit ccc5dc67340c ("mm/vmscan: make active/inactive ratio as 1:1 for anon lru"), most anon pages would live on the active LRU; the inactive one would contain only a handful of preselected reclaim candidates. After the series, anon gets aged similarly to file, and the inactive list is the default for new anon pages as well, making it often the much bigger list. As a result, the VM is now more likely to actually finish large anon targets than before. Change the code such that only one SWAP_CLUSTER_MAX-sized nudge toward the larger LRU lists is made before bailing out on a met reclaim goal. This fixes the extreme overreclaim problem. Fairness is more subtle and harder to evaluate. No obvious misbehavior was observed on the test workload, in any case. Conceptually, fairness should primarily be a cumulative effect from regular, lower priority scans. Once the VM is in trouble and needs to escalate scan targets to make forward progress, fairness needs to take a backseat. This is also acknowledged by the myriad exceptions in get_scan_count(). This patch makes fairness decrease gradually, as it keeps fairness work static over increasing priority levels with growing scan targets. This should make more sense - although we may have to re-visit the exact values. Link: https://lkml.kernel.org/r/20220802162811.39216-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@surriel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e4fea72b |
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28-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mglru: mm/vmscan.c: fix imprecise comments Link: https://lkml.kernel.org/r/YzSWfFI+MOeb1ils@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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14aa8b2d |
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28-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm/mglru: don't sync disk for each aging cycle wakeup_flusher_threads() was added under the assumption that if a system runs out of clean cold pages, it might want to write back dirty pages more aggressively so that they can become clean and be dropped. However, doing so can breach the rate limit a system wants to impose on writeback, resulting in early SSD wearout. Link: https://lkml.kernel.org/r/YzSiWq9UEER5LKup@google.com Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Yu Zhao <yuzhao@google.com> Reported-by: Axel Rasmussen <axelrasmussen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9202d527b |
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02-Sep-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
memcg: convert mem_cgroup_swap_full() to take a folio All callers now have a folio, so convert the function to take a folio. Saves a couple of calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-48-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4081f744 |
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02-Sep-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/swap: convert put_swap_page() to put_swap_folio() With all callers now using a folio, we can convert this function. Link: https://lkml.kernel.org/r/20220902194653.1739778-14-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bdb0ed54 |
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02-Sep-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/swapfile: convert try_to_free_swap() to folio_free_swap() Add kernel-doc for folio_free_swap() and make it return bool. Add a try_to_free_swap() compatibility wrapper. Link: https://lkml.kernel.org/r/20220902194653.1739778-11-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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49fd9b6d |
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02-Sep-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: fix a lot of comments Patch series "MM folio changes for 6.1", v2. My focus this round has been on shmem. I believe it is now fully converted to folios. Of course, shmem interacts with a lot of the swap cache and other parts of the kernel, so there are patches all over the MM. This patch series survives a round of xfstests on tmpfs, which is nice, but hardly an exhaustive test. Hugh was nice enough to run a round of tests on it and found a bug which is fixed in this edition. This patch (of 57): A lot of comments mention pages when they should say folios. Fix them up. [akpm@linux-foundation.org: fixups for mglru additions] Link: https://lkml.kernel.org/r/20220902194653.1739778-1-willy@infradead.org Link: https://lkml.kernel.org/r/20220902194653.1739778-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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78ba531f |
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06-Sep-2022 |
Liam R. Howlett <Liam.Howlett@oracle.com> |
mm/vmscan: use vma iterator instead of vm_next Use the vma iterator in in get_next_vma() instead of the linked list. [yuzhao@google.com: mm/vmscan: use the proper VMA iterator] Link: https://lkml.kernel.org/r/Yx+QGOgHg1Wk8tGK@google.com Link: https://lkml.kernel.org/r/20220906194824.2110408-68-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Yu Zhao <yuzhao@google.com> Tested-by: Yu Zhao <yuzhao@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: SeongJae Park <sj@kernel.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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32008027 |
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18-Aug-2022 |
Jagdish Gediya <jvgediya.oss@gmail.com> |
mm/demotion: demote pages according to allocation fallback order Currently, a higher tier node can only be demoted to selected nodes on the next lower tier as defined by the demotion path. This strict demotion order does not work in all use cases (e.g. some use cases may want to allow cross-socket demotion to another node in the same demotion tier as a fallback when the preferred demotion node is out of space). This demotion order is also inconsistent with the page allocation fallback order when all the nodes in a higher tier are out of space: The page allocation can fall back to any node from any lower tier, whereas the demotion order doesn't allow that currently. This patch adds support to get all the allowed demotion targets for a memory tier. demote_page_list() function is now modified to utilize this allowed node mask as the fallback allocation mask. Link: https://lkml.kernel.org/r/20220818131042.113280-9-aneesh.kumar@linux.ibm.com Signed-off-by: Jagdish Gediya <jvgediya.oss@gmail.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Wei Xu <weixugc@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Bharata B Rao <bharata@amd.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hesham Almatary <hesham.almatary@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Yang Shi <shy828301@gmail.com> Cc: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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91952440 |
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18-Aug-2022 |
Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> |
mm/demotion: move memory demotion related code This moves memory demotion related code to mm/memory-tiers.c. No functional change in this patch. Link: https://lkml.kernel.org/r/20220818131042.113280-3-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Wei Xu <weixugc@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Bharata B Rao <bharata@amd.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hesham Almatary <hesham.almatary@huawei.com> Cc: Jagdish Gediya <jvgediya.oss@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Yang Shi <shy828301@gmail.com> Cc: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
07017acb |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: admin guide Add an admin guide. Link: https://lkml.kernel.org/r/20220918080010.2920238-14-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d6c3af7d |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: debugfs interface Add /sys/kernel/debug/lru_gen for working set estimation and proactive reclaim. These techniques are commonly used to optimize job scheduling (bin packing) in data centers [1][2]. Compared with the page table-based approach and the PFN-based approach, this lruvec-based approach has the following advantages: 1. It offers better choices because it is aware of memcgs, NUMA nodes, shared mappings and unmapped page cache. 2. It is more scalable because it is O(nr_hot_pages), whereas the PFN-based approach is O(nr_total_pages). Add /sys/kernel/debug/lru_gen_full for debugging. [1] https://dl.acm.org/doi/10.1145/3297858.3304053 [2] https://dl.acm.org/doi/10.1145/3503222.3507731 Link: https://lkml.kernel.org/r/20220918080010.2920238-13-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
1332a809 |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: thrashing prevention Add /sys/kernel/mm/lru_gen/min_ttl_ms for thrashing prevention, as requested by many desktop users [1]. When set to value N, it prevents the working set of N milliseconds from getting evicted. The OOM killer is triggered if this working set cannot be kept in memory. Based on the average human detectable lag (~100ms), N=1000 usually eliminates intolerable lags due to thrashing. Larger values like N=3000 make lags less noticeable at the risk of premature OOM kills. Compared with the size-based approach [2], this time-based approach has the following advantages: 1. It is easier to configure because it is agnostic to applications and memory sizes. 2. It is more reliable because it is directly wired to the OOM killer. [1] https://lore.kernel.org/r/Ydza%2FzXKY9ATRoh6@google.com/ [2] https://lore.kernel.org/r/20101028191523.GA14972@google.com/ Link: https://lkml.kernel.org/r/20220918080010.2920238-12-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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354ed597 |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: kill switch Add /sys/kernel/mm/lru_gen/enabled as a kill switch. Components that can be disabled include: 0x0001: the multi-gen LRU core 0x0002: walking page table, when arch_has_hw_pte_young() returns true 0x0004: clearing the accessed bit in non-leaf PMD entries, when CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=y [yYnN]: apply to all the components above E.g., echo y >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0007 echo 5 >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0005 NB: the page table walks happen on the scale of seconds under heavy memory pressure, in which case the mmap_lock contention is a lesser concern, compared with the LRU lock contention and the I/O congestion. So far the only well-known case of the mmap_lock contention happens on Android, due to Scudo [1] which allocates several thousand VMAs for merely a few hundred MBs. The SPF and the Maple Tree also have provided their own assessments [2][3]. However, if walking page tables does worsen the mmap_lock contention, the kill switch can be used to disable it. In this case the multi-gen LRU will suffer a minor performance degradation, as shown previously. Clearing the accessed bit in non-leaf PMD entries can also be disabled, since this behavior was not tested on x86 varieties other than Intel and AMD. [1] https://source.android.com/devices/tech/debug/scudo [2] https://lore.kernel.org/r/20220128131006.67712-1-michel@lespinasse.org/ [3] https://lore.kernel.org/r/20220426150616.3937571-1-Liam.Howlett@oracle.com/ Link: https://lkml.kernel.org/r/20220918080010.2920238-11-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
f76c8337 |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: optimize multiple memcgs When multiple memcgs are available, it is possible to use generations as a frame of reference to make better choices and improve overall performance under global memory pressure. This patch adds a basic optimization to select memcgs that can drop single-use unmapped clean pages first. Doing so reduces the chance of going into the aging path or swapping, which can be costly. A typical example that benefits from this optimization is a server running mixed types of workloads, e.g., heavy anon workload in one memcg and heavy buffered I/O workload in the other. Though this optimization can be applied to both kswapd and direct reclaim, it is only added to kswapd to keep the patchset manageable. Later improvements may cover the direct reclaim path. While ensuring certain fairness to all eligible memcgs, proportional scans of individual memcgs also require proper backoff to avoid overshooting their aggregate reclaim target by too much. Otherwise it can cause high direct reclaim latency. The conditions for backoff are: 1. At low priorities, for direct reclaim, if aging fairness or direct reclaim latency is at risk, i.e., aging one memcg multiple times or swapping after the target is met. 2. At high priorities, for global reclaim, if per-zone free pages are above respective watermarks. Server benchmark results: Mixed workloads: fio (buffered I/O): +[19, 21]% IOPS BW patch1-8: 1880k 7343MiB/s patch1-9: 2252k 8796MiB/s memcached (anon): +[119, 123]% Ops/sec KB/sec patch1-8: 862768.65 33514.68 patch1-9: 1911022.12 74234.54 Mixed workloads: fio (buffered I/O): +[75, 77]% IOPS BW 5.19-rc1: 1279k 4996MiB/s patch1-9: 2252k 8796MiB/s memcached (anon): +[13, 15]% Ops/sec KB/sec 5.19-rc1: 1673524.04 65008.87 patch1-9: 1911022.12 74234.54 Configurations: (changes since patch 6) cat mixed.sh modprobe brd rd_nr=2 rd_size=56623104 swapoff -a mkswap /dev/ram0 swapon /dev/ram0 mkfs.ext4 /dev/ram1 mount -t ext4 /dev/ram1 /mnt memtier_benchmark -S /var/run/memcached/memcached.sock \ -P memcache_binary -n allkeys --key-minimum=1 \ --key-maximum=50000000 --key-pattern=P:P -c 1 -t 36 \ --ratio 1:0 --pipeline 8 -d 2000 fio -name=mglru --numjobs=36 --directory=/mnt --size=1408m \ --buffered=1 --ioengine=io_uring --iodepth=128 \ --iodepth_batch_submit=32 --iodepth_batch_complete=32 \ --rw=randread --random_distribution=random --norandommap \ --time_based --ramp_time=10m --runtime=90m --group_reporting & pid=$! sleep 200 memtier_benchmark -S /var/run/memcached/memcached.sock \ -P memcache_binary -n allkeys --key-minimum=1 \ --key-maximum=50000000 --key-pattern=R:R -c 1 -t 36 \ --ratio 0:1 --pipeline 8 --randomize --distinct-client-seed kill -INT $pid wait Client benchmark results: no change (CONFIG_MEMCG=n) Link: https://lkml.kernel.org/r/20220918080010.2920238-10-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bd74fdae |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: support page table walks To further exploit spatial locality, the aging prefers to walk page tables to search for young PTEs and promote hot pages. A kill switch will be added in the next patch to disable this behavior. When disabled, the aging relies on the rmap only. NB: this behavior has nothing similar with the page table scanning in the 2.4 kernel [1], which searches page tables for old PTEs, adds cold pages to swapcache and unmaps them. To avoid confusion, the term "iteration" specifically means the traversal of an entire mm_struct list; the term "walk" will be applied to page tables and the rmap, as usual. An mm_struct list is maintained for each memcg, and an mm_struct follows its owner task to the new memcg when this task is migrated. Given an lruvec, the aging iterates lruvec_memcg()->mm_list and calls walk_page_range() with each mm_struct on this list to promote hot pages before it increments max_seq. When multiple page table walkers iterate the same list, each of them gets a unique mm_struct; therefore they can run concurrently. Page table walkers ignore any misplaced pages, e.g., if an mm_struct was migrated, pages it left in the previous memcg will not be promoted when its current memcg is under reclaim. Similarly, page table walkers will not promote pages from nodes other than the one under reclaim. This patch uses the following optimizations when walking page tables: 1. It tracks the usage of mm_struct's between context switches so that page table walkers can skip processes that have been sleeping since the last iteration. 2. It uses generational Bloom filters to record populated branches so that page table walkers can reduce their search space based on the query results, e.g., to skip page tables containing mostly holes or misplaced pages. 3. It takes advantage of the accessed bit in non-leaf PMD entries when CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=y. 4. It does not zigzag between a PGD table and the same PMD table spanning multiple VMAs. IOW, it finishes all the VMAs within the range of the same PMD table before it returns to a PGD table. This improves the cache performance for workloads that have large numbers of tiny VMAs [2], especially when CONFIG_PGTABLE_LEVELS=5. Server benchmark results: Single workload: fio (buffered I/O): no change Single workload: memcached (anon): +[8, 10]% Ops/sec KB/sec patch1-7: 1147696.57 44640.29 patch1-8: 1245274.91 48435.66 Configurations: no change Client benchmark results: kswapd profiles: patch1-7 48.16% lzo1x_1_do_compress (real work) 8.20% page_vma_mapped_walk (overhead) 7.06% _raw_spin_unlock_irq 2.92% ptep_clear_flush 2.53% __zram_bvec_write 2.11% do_raw_spin_lock 2.02% memmove 1.93% lru_gen_look_around 1.56% free_unref_page_list 1.40% memset patch1-8 49.44% lzo1x_1_do_compress (real work) 6.19% page_vma_mapped_walk (overhead) 5.97% _raw_spin_unlock_irq 3.13% get_pfn_folio 2.85% ptep_clear_flush 2.42% __zram_bvec_write 2.08% do_raw_spin_lock 1.92% memmove 1.44% alloc_zspage 1.36% memset Configurations: no change Thanks to the following developers for their efforts [3]. kernel test robot <lkp@intel.com> [1] https://lwn.net/Articles/23732/ [2] https://llvm.org/docs/ScudoHardenedAllocator.html [3] https://lore.kernel.org/r/202204160827.ekEARWQo-lkp@intel.com/ Link: https://lkml.kernel.org/r/20220918080010.2920238-9-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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018ee47f |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: exploit locality in rmap Searching the rmap for PTEs mapping each page on an LRU list (to test and clear the accessed bit) can be expensive because pages from different VMAs (PA space) are not cache friendly to the rmap (VA space). For workloads mostly using mapped pages, searching the rmap can incur the highest CPU cost in the reclaim path. This patch exploits spatial locality to reduce the trips into the rmap. When shrink_page_list() walks the rmap and finds a young PTE, a new function lru_gen_look_around() scans at most BITS_PER_LONG-1 adjacent PTEs. On finding another young PTE, it clears the accessed bit and updates the gen counter of the page mapped by this PTE to (max_seq%MAX_NR_GENS)+1. Server benchmark results: Single workload: fio (buffered I/O): no change Single workload: memcached (anon): +[3, 5]% Ops/sec KB/sec patch1-6: 1106168.46 43025.04 patch1-7: 1147696.57 44640.29 Configurations: no change Client benchmark results: kswapd profiles: patch1-6 39.03% lzo1x_1_do_compress (real work) 18.47% page_vma_mapped_walk (overhead) 6.74% _raw_spin_unlock_irq 3.97% do_raw_spin_lock 2.49% ptep_clear_flush 2.48% anon_vma_interval_tree_iter_first 1.92% folio_referenced_one 1.88% __zram_bvec_write 1.48% memmove 1.31% vma_interval_tree_iter_next patch1-7 48.16% lzo1x_1_do_compress (real work) 8.20% page_vma_mapped_walk (overhead) 7.06% _raw_spin_unlock_irq 2.92% ptep_clear_flush 2.53% __zram_bvec_write 2.11% do_raw_spin_lock 2.02% memmove 1.93% lru_gen_look_around 1.56% free_unref_page_list 1.40% memset Configurations: no change Link: https://lkml.kernel.org/r/20220918080010.2920238-8-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Barry Song <baohua@kernel.org> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
ac35a490 |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: minimal implementation To avoid confusion, the terms "promotion" and "demotion" will be applied to the multi-gen LRU, as a new convention; the terms "activation" and "deactivation" will be applied to the active/inactive LRU, as usual. The aging produces young generations. Given an lruvec, it increments max_seq when max_seq-min_seq+1 approaches MIN_NR_GENS. The aging promotes hot pages to the youngest generation when it finds them accessed through page tables; the demotion of cold pages happens consequently when it increments max_seq. Promotion in the aging path does not involve any LRU list operations, only the updates of the gen counter and lrugen->nr_pages[]; demotion, unless as the result of the increment of max_seq, requires LRU list operations, e.g., lru_deactivate_fn(). The aging has the complexity O(nr_hot_pages), since it is only interested in hot pages. The eviction consumes old generations. Given an lruvec, it increments min_seq when lrugen->lists[] indexed by min_seq%MAX_NR_GENS becomes empty. A feedback loop modeled after the PID controller monitors refaults over anon and file types and decides which type to evict when both types are available from the same generation. The protection of pages accessed multiple times through file descriptors takes place in the eviction path. Each generation is divided into multiple tiers. A page accessed N times through file descriptors is in tier order_base_2(N). Tiers do not have dedicated lrugen->lists[], only bits in folio->flags. The aforementioned feedback loop also monitors refaults over all tiers and decides when to protect pages in which tiers (N>1), using the first tier (N=0,1) as a baseline. The first tier contains single-use unmapped clean pages, which are most likely the best choices. In contrast to promotion in the aging path, the protection of a page in the eviction path is achieved by moving this page to the next generation, i.e., min_seq+1, if the feedback loop decides so. This approach has the following advantages: 1. It removes the cost of activation in the buffered access path by inferring whether pages accessed multiple times through file descriptors are statistically hot and thus worth protecting in the eviction path. 2. It takes pages accessed through page tables into account and avoids overprotecting pages accessed multiple times through file descriptors. (Pages accessed through page tables are in the first tier, since N=0.) 3. More tiers provide better protection for pages accessed more than twice through file descriptors, when under heavy buffered I/O workloads. Server benchmark results: Single workload: fio (buffered I/O): +[30, 32]% IOPS BW 5.19-rc1: 2673k 10.2GiB/s patch1-6: 3491k 13.3GiB/s Single workload: memcached (anon): -[4, 6]% Ops/sec KB/sec 5.19-rc1: 1161501.04 45177.25 patch1-6: 1106168.46 43025.04 Configurations: CPU: two Xeon 6154 Mem: total 256G Node 1 was only used as a ram disk to reduce the variance in the results. patch drivers/block/brd.c <<EOF 99,100c99,100 < gfp_flags = GFP_NOIO | __GFP_ZERO | __GFP_HIGHMEM; < page = alloc_page(gfp_flags); --- > gfp_flags = GFP_NOIO | __GFP_ZERO | __GFP_HIGHMEM | __GFP_THISNODE; > page = alloc_pages_node(1, gfp_flags, 0); EOF cat >>/etc/systemd/system.conf <<EOF CPUAffinity=numa NUMAPolicy=bind NUMAMask=0 EOF cat >>/etc/memcached.conf <<EOF -m 184320 -s /var/run/memcached/memcached.sock -a 0766 -t 36 -B binary EOF cat fio.sh modprobe brd rd_nr=1 rd_size=113246208 swapoff -a mkfs.ext4 /dev/ram0 mount -t ext4 /dev/ram0 /mnt mkdir /sys/fs/cgroup/user.slice/test echo 38654705664 >/sys/fs/cgroup/user.slice/test/memory.max echo $$ >/sys/fs/cgroup/user.slice/test/cgroup.procs fio -name=mglru --numjobs=72 --directory=/mnt --size=1408m \ --buffered=1 --ioengine=io_uring --iodepth=128 \ --iodepth_batch_submit=32 --iodepth_batch_complete=32 \ --rw=randread --random_distribution=random --norandommap \ --time_based --ramp_time=10m --runtime=5m --group_reporting cat memcached.sh modprobe brd rd_nr=1 rd_size=113246208 swapoff -a mkswap /dev/ram0 swapon /dev/ram0 memtier_benchmark -S /var/run/memcached/memcached.sock \ -P memcache_binary -n allkeys --key-minimum=1 \ --key-maximum=65000000 --key-pattern=P:P -c 1 -t 36 \ --ratio 1:0 --pipeline 8 -d 2000 memtier_benchmark -S /var/run/memcached/memcached.sock \ -P memcache_binary -n allkeys --key-minimum=1 \ --key-maximum=65000000 --key-pattern=R:R -c 1 -t 36 \ --ratio 0:1 --pipeline 8 --randomize --distinct-client-seed Client benchmark results: kswapd profiles: 5.19-rc1 40.33% page_vma_mapped_walk (overhead) 21.80% lzo1x_1_do_compress (real work) 7.53% do_raw_spin_lock 3.95% _raw_spin_unlock_irq 2.52% vma_interval_tree_iter_next 2.37% folio_referenced_one 2.28% vma_interval_tree_subtree_search 1.97% anon_vma_interval_tree_iter_first 1.60% ptep_clear_flush 1.06% __zram_bvec_write patch1-6 39.03% lzo1x_1_do_compress (real work) 18.47% page_vma_mapped_walk (overhead) 6.74% _raw_spin_unlock_irq 3.97% do_raw_spin_lock 2.49% ptep_clear_flush 2.48% anon_vma_interval_tree_iter_first 1.92% folio_referenced_one 1.88% __zram_bvec_write 1.48% memmove 1.31% vma_interval_tree_iter_next Configurations: CPU: single Snapdragon 7c Mem: total 4G ChromeOS MemoryPressure [1] [1] https://chromium.googlesource.com/chromiumos/platform/tast-tests/ Link: https://lkml.kernel.org/r/20220918080010.2920238-7-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
ec1c86b2 |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm: multi-gen LRU: groundwork Evictable pages are divided into multiple generations for each lruvec. The youngest generation number is stored in lrugen->max_seq for both anon and file types as they are aged on an equal footing. The oldest generation numbers are stored in lrugen->min_seq[] separately for anon and file types as clean file pages can be evicted regardless of swap constraints. These three variables are monotonically increasing. Generation numbers are truncated into order_base_2(MAX_NR_GENS+1) bits in order to fit into the gen counter in folio->flags. Each truncated generation number is an index to lrugen->lists[]. The sliding window technique is used to track at least MIN_NR_GENS and at most MAX_NR_GENS generations. The gen counter stores a value within [1, MAX_NR_GENS] while a page is on one of lrugen->lists[]. Otherwise it stores 0. There are two conceptually independent procedures: "the aging", which produces young generations, and "the eviction", which consumes old generations. They form a closed-loop system, i.e., "the page reclaim". Both procedures can be invoked from userspace for the purposes of working set estimation and proactive reclaim. These techniques are commonly used to optimize job scheduling (bin packing) in data centers [1][2]. To avoid confusion, the terms "hot" and "cold" will be applied to the multi-gen LRU, as a new convention; the terms "active" and "inactive" will be applied to the active/inactive LRU, as usual. The protection of hot pages and the selection of cold pages are based on page access channels and patterns. There are two access channels: one through page tables and the other through file descriptors. The protection of the former channel is by design stronger because: 1. The uncertainty in determining the access patterns of the former channel is higher due to the approximation of the accessed bit. 2. The cost of evicting the former channel is higher due to the TLB flushes required and the likelihood of encountering the dirty bit. 3. The penalty of underprotecting the former channel is higher because applications usually do not prepare themselves for major page faults like they do for blocked I/O. E.g., GUI applications commonly use dedicated I/O threads to avoid blocking rendering threads. There are also two access patterns: one with temporal locality and the other without. For the reasons listed above, the former channel is assumed to follow the former pattern unless VM_SEQ_READ or VM_RAND_READ is present; the latter channel is assumed to follow the latter pattern unless outlying refaults have been observed [3][4]. The next patch will address the "outlying refaults". Three macros, i.e., LRU_REFS_WIDTH, LRU_REFS_PGOFF and LRU_REFS_MASK, used later are added in this patch to make the entire patchset less diffy. A page is added to the youngest generation on faulting. The aging needs to check the accessed bit at least twice before handing this page over to the eviction. The first check takes care of the accessed bit set on the initial fault; the second check makes sure this page has not been used since then. This protocol, AKA second chance, requires a minimum of two generations, hence MIN_NR_GENS. [1] https://dl.acm.org/doi/10.1145/3297858.3304053 [2] https://dl.acm.org/doi/10.1145/3503222.3507731 [3] https://lwn.net/Articles/495543/ [4] https://lwn.net/Articles/815342/ Link: https://lkml.kernel.org/r/20220918080010.2920238-6-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f1e1a7be |
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18-Sep-2022 |
Yu Zhao <yuzhao@google.com> |
mm/vmscan.c: refactor shrink_node() This patch refactors shrink_node() to improve readability for the upcoming changes to mm/vmscan.c. Link: https://lkml.kernel.org/r/20220918080010.2920238-4-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Barry Song <baohua@kernel.org> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b4a0215e |
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27-Aug-2022 |
Kefeng Wang <wangkefeng.wang@huawei.com> |
mm: fix null-ptr-deref in kswapd_is_running() kswapd_run/stop() will set pgdat->kswapd to NULL, which could race with kswapd_is_running() in kcompactd(), kswapd_run/stop() kcompactd() kswapd_is_running() pgdat->kswapd // error or nomal ptr verify pgdat->kswapd // load non-NULL pgdat->kswapd pgdat->kswapd = NULL task_is_running(pgdat->kswapd) // Null pointer derefence KASAN reports the null-ptr-deref shown below, vmscan: Failed to start kswapd on node 0 ... BUG: KASAN: null-ptr-deref in kcompactd+0x440/0x504 Read of size 8 at addr 0000000000000024 by task kcompactd0/37 CPU: 0 PID: 37 Comm: kcompactd0 Kdump: loaded Tainted: G OE 5.10.60 #1 Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 Call trace: dump_backtrace+0x0/0x394 show_stack+0x34/0x4c dump_stack+0x158/0x1e4 __kasan_report+0x138/0x140 kasan_report+0x44/0xdc __asan_load8+0x94/0xd0 kcompactd+0x440/0x504 kthread+0x1a4/0x1f0 ret_from_fork+0x10/0x18 At present kswapd/kcompactd_run() and kswapd/kcompactd_stop() are protected by mem_hotplug_begin/done(), but without kcompactd(). There is no need to involve memory hotplug lock in kcompactd(), so let's add a new mutex to protect pgdat->kswapd accesses. Also, because the kcompactd task will check the state of kswapd task, it's better to call kcompactd_stop() before kswapd_stop() to reduce lock conflicts. [akpm@linux-foundation.org: add comments] Link: https://lkml.kernel.org/r/20220827111959.186838-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: David Hildenbrand <david@redhat.com> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d3629af5 |
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13-Aug-2022 |
Yang Yang <yang.yang29@zte.com.cn> |
mm/vmscan: make the annotations of refaults code at the right place After patch "mm/workingset: prepare the workingset detection infrastructure for anon LRU", we can handle the refaults of anonymous pages too. So the annotations of refaults should cover both of anonymous pages and file pages. Link: https://lkml.kernel.org/r/20220813080757.59131-1-yang.yang29@zte.com.cn Fixes: 170b04b7ae4963 ("mm/workingset: prepare the workingset detection infrastructure for anon LRU") Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: CGEL ZTE <cgel.zte@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e9c2dbc8 |
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07-Aug-2022 |
Yang Yang <yang.yang29@zte.com.cn> |
mm/vmscan: define macros for refaults in struct lruvec The magic number 0 and 1 are used in several places in vmscan.c. Define macros for them to improve code readability. Link: https://lkml.kernel.org/r/20220808005644.1721066-1-yang.yang29@zte.com.cn Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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36a3b14b |
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02-Sep-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: check folio_test_private(), not folio_get_private() These two predicates are the same for file pages, but are not the same for anonymous pages. Link: https://lkml.kernel.org/r/20220902192639.1737108-3-willy@infradead.org Fixes: 07f67a8dedc0 ("mm/vmscan: convert shrink_active_list() to use a folio") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reported-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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73b73bac |
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14-Jul-2022 |
Yosry Ahmed <yosryahmed@google.com> |
mm: vmpressure: don't count proactive reclaim in vmpressure memory.reclaim is a cgroup v2 interface that allows users to proactively reclaim memory from a memcg, without real memory pressure. Reclaim operations invoke vmpressure, which is used: (a) To notify userspace of reclaim efficiency in cgroup v1, and (b) As a signal for a memcg being under memory pressure for networking (see mem_cgroup_under_socket_pressure()). For (a), vmpressure notifications in v1 are not affected by this change since memory.reclaim is a v2 feature. For (b), the effects of the vmpressure signal (according to Shakeel [1]) are as follows: 1. Reducing send and receive buffers of the current socket. 2. May drop packets on the rx path. 3. May throttle current thread on the tx path. Since proactive reclaim is invoked directly by userspace, not by memory pressure, it makes sense not to throttle networking. Hence, this change makes sure that proactive reclaim caused by memory.reclaim does not trigger vmpressure. [1] https://lore.kernel.org/lkml/CALvZod68WdrXEmBpOkadhB5GPYmCXaDZzXH=yyGOCAjFRn4NDQ@mail.gmail.com/ [yosryahmed@google.com: update documentation] Link: https://lkml.kernel.org/r/20220721173015.2643248-1-yosryahmed@google.com Link: https://lkml.kernel.org/r/20220714064918.2576464-1-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: NeilBrown <neilb@suse.de> Cc: Alistair Popple <apopple@nvidia.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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14773bfa |
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20-Jul-2022 |
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
mm: shrinkers: fix double kfree on shrinker name syzbot is reporting double kfree() at free_prealloced_shrinker() [1], for destroy_unused_super() calls free_prealloced_shrinker() even if prealloc_shrinker() returned an error. Explicitly clear shrinker name when prealloc_shrinker() called kfree(). [roman.gushchin@linux.dev: zero shrinker->name in all cases where shrinker->name is freed] Link: https://lkml.kernel.org/r/YtgteTnQTgyuKUSY@castle Link: https://syzkaller.appspot.com/bug?extid=8b481578352d4637f510 [1] Link: https://lkml.kernel.org/r/ffa62ece-6a42-2644-16cf-0d33ef32c676@I-love.SAKURA.ne.jp Fixes: e33c267ab70de424 ("mm: shrinkers: provide shrinkers with names") Reported-by: syzbot <syzbot+8b481578352d4637f510@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e8da368a |
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20-Jun-2022 |
Yun-Ze Li <p76091292@gs.ncku.edu.tw> |
mm, docs: fix comments that mention mem_hotplug_end() Comments that mention mem_hotplug_end() are confusing as there is no function called mem_hotplug_end(). Fix them by replacing all the occurences of mem_hotplug_end() in the comments with mem_hotplug_done(). [akpm@linux-foundation.org: grammatical fixes] Link: https://lkml.kernel.org/r/20220620071516.1286101-1-p76091292@gs.ncku.edu.tw Signed-off-by: Yun-Ze Li <p76091292@gs.ncku.edu.tw> Cc: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ceff9d33 |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/swap: convert __delete_from_swap_cache() to a folio All callers now have a folio, so convert the entire function to operate on folios. Link: https://lkml.kernel.org/r/20220617175020.717127-23-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b98c359f |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: convert page_swap_flags to folio_swap_flags The only caller already has a folio, so push the folio->page conversion down a level. Link: https://lkml.kernel.org/r/20220617175020.717127-21-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5375336c |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: convert destroy_compound_page() to destroy_large_folio() All callers now have a folio, so push the folio->page conversion down to this function. [akpm@linux-foundation.org: uninline destroy_large_folio() to fix build issue] Link: https://lkml.kernel.org/r/20220617175020.717127-20-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a83f0551 |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: convert reclaim_pages() to use a folio Remove a few hidden calls to compound_head, saving 76 bytes of text. Link: https://lkml.kernel.org/r/20220617154248.700416-6-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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07f67a8d |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: convert shrink_active_list() to use a folio Remove a few hidden calls to compound_head, saving 411 bytes of text. Link: https://lkml.kernel.org/r/20220617154248.700416-5-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ff00a170 |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: convert move_pages_to_lru() to use a folio Remove a few hidden calls to compound_head, saving 387 bytes of text on my test configuration. Link: https://lkml.kernel.org/r/20220617154248.700416-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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166e3d32 |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: convert isolate_lru_pages() to use a folio Remove a few hidden calls to compound_head, saving 279 bytes of text. Link: https://lkml.kernel.org/r/20220617154248.700416-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b8cecb93 |
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17-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: convert reclaim_clean_pages_from_list() to folios Patch series "nvert much of vmscan to folios" vmscan always operates on folios since it puts the pages on the LRU list. Switching all of these functions from pages to folios saves 1483 bytes of text from removing all the baggage around calling compound_page() and similar functions. This patch (of 5): This is a straightforward conversion which removes several hidden calls to compound_head, saving 330 bytes of kernel text. Link: https://lkml.kernel.org/r/20220617154248.700416-1-willy@infradead.org Link: https://lkml.kernel.org/r/20220617154248.700416-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e33c267a |
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31-May-2022 |
Roman Gushchin <roman.gushchin@linux.dev> |
mm: shrinkers: provide shrinkers with names Currently shrinkers are anonymous objects. For debugging purposes they can be identified by count/scan function names, but it's not always useful: e.g. for superblock's shrinkers it's nice to have at least an idea of to which superblock the shrinker belongs. This commit adds names to shrinkers. register_shrinker() and prealloc_shrinker() functions are extended to take a format and arguments to master a name. In some cases it's not possible to determine a good name at the time when a shrinker is allocated. For such cases shrinker_debugfs_rename() is provided. The expected format is: <subsystem>-<shrinker_type>[:<instance>]-<id> For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair. After this change the shrinker debugfs directory looks like: $ cd /sys/kernel/debug/shrinker/ $ ls dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42 mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43 mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44 rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49 sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13 sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36 sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19 sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10 sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9 sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37 sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38 sb-dax-11 sb-proc-45 sb-tmpfs-35 sb-debugfs-7 sb-proc-46 sb-tmpfs-40 [roman.gushchin@linux.dev: fix build warnings] Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle Reported-by: kernel test robot <lkp@intel.com> Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Dave Chinner <dchinner@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5035ebc6 |
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31-May-2022 |
Roman Gushchin <roman.gushchin@linux.dev> |
mm: shrinkers: introduce debugfs interface for memory shrinkers This commit introduces the /sys/kernel/debug/shrinker debugfs interface which provides an ability to observe the state of individual kernel memory shrinkers. Because the feature adds some memory overhead (which shouldn't be large unless there is a huge amount of registered shrinkers), it's guarded by a config option (enabled by default). This commit introduces the "count" interface for each shrinker registered in the system. The output is in the following format: <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>... <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>... ... To reduce the size of output on machines with many thousands cgroups, if the total number of objects on all nodes is 0, the line is omitted. If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is printed as cgroup inode id. If the shrinker is not numa-aware, 0's are printed for all nodes except the first one. This commit gives debugfs entries simple numeric names, which are not very convenient. The following commit in the series will provide shrinkers with more meaningful names. [akpm@linux-foundation.org: remove WARN_ON_ONCE(), per Roman] Reported-by: syzbot+300d27c79fe6d4cbcc39@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/20220601032227.4076670-3-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com> Acked-by: Muchun Song <songmuchun@bytedance.com> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Dave Chinner <dchinner@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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77414d19 |
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04-Jun-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: Add check_move_unevictable_folios() Change the guts of check_move_unevictable_pages() over to use folios and add check_move_unevictable_pages() as a wrapper. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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3f1509c5 |
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18-May-2022 |
Johannes Weiner <hannes@cmpxchg.org> |
Revert "mm/vmscan: never demote for memcg reclaim" This reverts commit 3a235693d3930e1276c8d9cc0ca5807ef292cf0a. Its premise was that cgroup reclaim cares about freeing memory inside the cgroup, and demotion just moves them around within the cgroup limit. Hence, pages from toptier nodes should be reclaimed directly. However, with NUMA balancing now doing tier promotions, demotion is part of the page aging process. Global reclaim demotes the coldest toptier pages to secondary memory, where their life continues and from which they have a chance to get promoted back. Essentially, tiered memory systems have an LRU order that spans multiple nodes. When cgroup reclaims pages coming off the toptier directly, there can be colder pages on lower tier nodes that were demoted by global reclaim. This is an aging inversion, not unlike if cgroups were to reclaim directly from the active lists while there are inactive pages. Proactive reclaim is another factor. The goal of that it is to offload colder pages from expensive RAM to cheaper storage. When lower tier memory is available as an intermediate layer, we want offloading to take advantage of it instead of bypassing to storage. Revert the patch so that cgroups respect the LRU order spanning the memory hierarchy. Of note is a specific undercommit scenario, where all cgroup limits in the system add up to <= available toptier memory. In that case, shuffling pages out to lower tiers first to reclaim them from there is inefficient. This is something could be optimized/short-circuited later on (although care must be taken not to accidentally recreate the aging inversion). Let's ensure correctness first. Link: https://lkml.kernel.org/r/20220518190911.82400-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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6d4675e6 |
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19-May-2022 |
Minchan Kim <minchan@kernel.org> |
mm: don't be stuck to rmap lock on reclaim path The rmap locks(i_mmap_rwsem and anon_vma->root->rwsem) could be contended under memory pressure if processes keep working on their vmas(e.g., fork, mmap, munmap). It makes reclaim path stuck. In our real workload traces, we see kswapd is waiting the lock for 300ms+(worst case, a sec) and it makes other processes entering direct reclaim, which were also stuck on the lock. This patch makes lru aging path try_lock mode like shink_page_list so the reclaim context will keep working with next lru pages without being stuck. if it found the rmap lock contended, it rotates the page back to head of lru in both active/inactive lrus to make them consistent behavior, which is basic starting point rather than adding more heristic. Since this patch introduces a new "contended" field as out-param along with try_lock in-param in rmap_walk_control, it's not immutable any longer if the try_lock is set so remove const keywords on rmap related functions. Since rmap walking is already expensive operation, I doubt the const would help sizable benefit( And we didn't have it until 5.17). In a heavy app workload in Android, trace shows following statistics. It almost removes rmap lock contention from reclaim path. Martin Liu reported: Before: max_dur(ms) min_dur(ms) max-min(dur)ms avg_dur(ms) sum_dur(ms) count blocked_function 1632 0 1631 151.542173 31672 209 page_lock_anon_vma_read 601 0 601 145.544681 28817 198 rmap_walk_file After: max_dur(ms) min_dur(ms) max-min(dur)ms avg_dur(ms) sum_dur(ms) count blocked_function NaN NaN NaN NaN NaN 0.0 NaN 0 0 0 0.127645 1 12 rmap_walk_file [minchan@kernel.org: add comment, per Matthew] Link: https://lkml.kernel.org/r/YnNqeB5tUf6LZ57b@google.com Link: https://lkml.kernel.org/r/20220510215423.164547-1-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: John Dias <joaodias@google.com> Cc: Tim Murray <timmurray@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Martin Liu <liumartin@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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c28a0e96 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: remove remaining uses of page in shrink_page_list These are all straightforward conversions to the folio API. Link: https://lkml.kernel.org/r/20220504182857.4013401-16-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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246b6480 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: convert the activate_locked portion of shrink_page_list to folios This accounts the number of pages activated correctly for large folios. Link: https://lkml.kernel.org/r/20220504182857.4013401-14-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5441d490 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: move initialisation of mapping down Now that we don't interrogate the BDI for congestion, we can delay looking up the folio's mapping until we've got further through the function, reducing register pressure and saving a call to folio_mapping for folios we're adding to the swap cache. Link: https://lkml.kernel.org/r/20220504182857.4013401-13-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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64daa5d8 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: convert lazy freeing to folios Remove a hidden call to compound_head(), and account nr_pages instead of a single page. This matches the code in lru_lazyfree_fn() that accounts nr_pages to PGLAZYFREE. Link: https://lkml.kernel.org/r/20220504182857.4013401-12-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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0a36111c |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: convert page buffer handling to use folios This mostly just removes calls to compound_head() although nr_reclaimed should be incremented by the number of pages, not just 1. Link: https://lkml.kernel.org/r/20220504182857.4013401-11-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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49bd2bf9 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: convert dirty page handling to folios Mostly this just eliminates calls to compound_head(), but NR_VMSCAN_IMMEDIATE was being incremented by 1 instead of by nr_pages. Link: https://lkml.kernel.org/r/20220504182857.4013401-10-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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09c02e56 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
swap: convert add_to_swap() to take a folio The only caller already has a folio available, so this saves a conversion. Also convert the return type to boolean. Link: https://lkml.kernel.org/r/20220504182857.4013401-9-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d33e4e14 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: convert the writeback handling in shrink_page_list() to folios Slightly more efficient due to fewer calls to compound_head(). Link: https://lkml.kernel.org/r/20220504182857.4013401-7-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1bee2c16 |
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12-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
vmscan: use folio_mapped() in shrink_page_list() Remove some legacy function calls. Link: https://lkml.kernel.org/r/20220504182857.4013401-6-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ed657e55 |
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12-May-2022 |
Wei Yang <richard.weiyang@gmail.com> |
mm/vmscan: don't use NUMA_NO_NODE as indicator of page on different node Now we are sure there is at least one page on page_list, so it is safe to get the nid of it. This means it is not necessary to use NUMA_NO_NODE as an indicator for the beginning of iteration or a page on different node. Link: https://lkml.kernel.org/r/20220429014426.29223-2-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1ae65e27 |
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12-May-2022 |
Wei Yang <richard.weiyang@gmail.com> |
mm/vmscan: filter empty page_list at the beginning node_page_list would always be !empty on finishing the loop, except page_list is empty. Let's handle empty page_list before doing any real work including touching PF_MEMALLOC flag. Link: https://lkml.kernel.org/r/20220429014426.29223-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f19a27e3 |
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12-May-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: use helper folio_is_file_lru() Use helper folio_is_file_lru() to check whether folio is file lru. Minor readability improvement. [linmiaohe@huawei.com: use folio_is_file_lru()] Link: https://lkml.kernel.org/r/20220428105802.21389-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20220425111232.23182-7-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Huang, Ying <ying.huang@intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4355e4b2 |
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12-May-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: remove obsolete comment in kswapd_run Since commit 6b700b5b3c59 ("mm/vmscan.c: remove cpu online notification for now"), cpu online notification is removed. So kswapd won't move to proper cpus if cpus are hot-added. Remove this obsolete comment. Link: https://lkml.kernel.org/r/20220425111232.23182-6-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Huang, Ying <ying.huang@intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9aafcffc |
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12-May-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: take all base pages of THP into account when race with speculative reference If the page has buffers, shrink_page_list will try to free the buffer mappings associated with the page and try to free the page as well. In the rare race with speculative reference, the page will be freed shortly by speculative reference. But nr_reclaimed is not incremented correctly when we come across the THP. We need to account all the base pages in this case. Link: https://lkml.kernel.org/r/20220425111232.23182-5-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Huang, Ying <ying.huang@intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1fe47c0b |
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12-May-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: introduce helper function reclaim_page_list() Introduce helper function reclaim_page_list() to eliminate the duplicated code of doing shrink_page_list() and putback_lru_page. Also we can separate node reclaim from node page list operation this way. No functional change intended. Link: https://lkml.kernel.org/r/20220425111232.23182-3-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Huang, Ying <ying.huang@intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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32a331a7 |
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12-May-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: add a comment about MADV_FREE pages check in folio_check_dirty_writeback Patch series "A few cleanup and fixup patches for vmscan This series contains a few patches to remove obsolete comment, introduce helper to remove duplicated code and so no. Also we take all base pages of THP into account in rare race condition. More details can be found in the respective changelogs. This patch (of 6): The MADV_FREE pages check in folio_check_dirty_writeback is a bit hard to follow. Add a comment to make the code clear. Link: https://lkml.kernel.org/r/20220425111232.23182-2-linmiaohe@huawei.com Suggested-by: Huang, Ying <ying.huang@intel.com> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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048f6e1a |
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12-May-2022 |
Wei Yang <richard.weiyang@gmail.com> |
mm/vmscan: not necessary to re-init the list for each iteration node_page_list is defined with LIST_HEAD and be cleaned until list_empty. So it is not necessary to re-init it again. [akpm@linux-foundation.org: remove unneeded braces] Link: https://lkml.kernel.org/r/20220426021743.21007-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d8ff6fde |
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12-May-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: take min_slab_pages into account when try to call shrink_node Since commit 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from shrink_zone()"), slab reclaim and lru page reclaim are done together in the shrink_node. So we should take min_slab_pages into account when try to call shrink_node. Link: https://lkml.kernel.org/r/20220425112118.20924-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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2282679f |
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09-May-2022 |
NeilBrown <neilb@suse.de> |
mm: submit multipage write for SWP_FS_OPS swap-space swap_writepage() is given one page at a time, but may be called repeatedly in succession. For block-device swapspace, the blk_plug functionality allows the multiple pages to be combined together at lower layers. That cannot be used for SWP_FS_OPS as blk_plug may not exist - it is only active when CONFIG_BLOCK=y. Consequently all swap reads over NFS are single page reads. With this patch we pass a pointer-to-pointer via the wbc. swap_writepage can store state between calls - much like the pointer passed explicitly to swap_readpage. After calling swap_writepage() some number of times, the state will be passed to swap_write_unplug() which can submit the combined request. Link: https://lkml.kernel.org/r/164859778128.29473.5191868522654408537.stgit@noble.brown Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: David Howells <dhowells@redhat.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d791ea67 |
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09-May-2022 |
NeilBrown <neilb@suse.de> |
mm: reclaim mustn't enter FS for SWP_FS_OPS swap-space If swap-out is using filesystem operations (SWP_FS_OPS), then it is not safe to enter the FS for reclaim. So only down-grade the requirement for swap pages to __GFP_IO after checking that SWP_FS_OPS are not being used. This makes the calculation of "may_enter_fs" slightly more complex, so move it into a separate function. with that done, there is little value in maintaining the bool variable any more. So replace the may_enter_fs variable with a may_enter_fs() function. This removes any risk for the variable becoming out-of-date. Link: https://lkml.kernel.org/r/164859778124.29473.16176717935781721855.stgit@noble.brown Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: David Howells <dhowells@redhat.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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014bb1de |
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09-May-2022 |
NeilBrown <neilb@suse.de> |
mm: create new mm/swap.h header file Patch series "MM changes to improve swap-over-NFS support". Assorted improvements for swap-via-filesystem. This is a resend of these patches, rebased on current HEAD. The only substantial changes is that swap_dirty_folio has replaced swap_set_page_dirty. Currently swap-via-fs (SWP_FS_OPS) doesn't work for any filesystem. It has previously worked for NFS but that broke a few releases back. This series changes to use a new ->swap_rw rather than ->readpage and ->direct_IO. It also makes other improvements. There is a companion series already in linux-next which fixes various issues with NFS. Once both series land, a final patch is needed which changes NFS over to use ->swap_rw. This patch (of 10): Many functions declared in include/linux/swap.h are only used within mm/ Create a new "mm/swap.h" and move some of these declarations there. Remove the redundant 'extern' from the function declarations. [akpm@linux-foundation.org: mm/memory-failure.c needs mm/swap.h] Link: https://lkml.kernel.org/r/164859751830.29473.5309689752169286816.stgit@noble.brown Link: https://lkml.kernel.org/r/164859778120.29473.11725907882296224053.stgit@noble.brown Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: David Howells <dhowells@redhat.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b2cb6826 |
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29-Apr-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: fix comment for isolate_lru_pages Since commit 791b48b64232 ("mm: vmscan: scan until it finds eligible pages"), splicing any skipped pages to the tail of the LRU list won't put the system at risk of premature OOM but will waste lots of cpu cycles. Correct the comment accordingly. Link: https://lkml.kernel.org/r/20220416025231.8082-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5829f7db |
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29-Apr-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: fix comment for current_may_throttle Since commit 6d6435811c19 ("remove bdi_congested() and wb_congested() and related functions"), there is no congested backing device check anymore. Correct the comment accordingly. [akpm@linux-foundation.org: tweak grammar] Link: https://lkml.kernel.org/r/20220414120202.30082-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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02e458d8 |
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29-Apr-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: remove obsolete comment in get_scan_count Since commit 1431d4d11abb ("mm: base LRU balancing on an explicit cost model"), the relative value of each set of LRU lists is based on cost model instead of rotated/scanned ratio. Cleanup the relevant comment. Link: https://lkml.kernel.org/r/20220409030245.61211-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8b3a899a |
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29-Apr-2022 |
Wei Yang <richard.weiyang@gmail.com> |
mm/vmscan: sc->reclaim_idx must be a valid zone index lruvec_lru_size() is only used in get_scan_count(), so the only possible zone_idx is sc->reclaim_idx. Since sc->reclaim_idx is ensured to be a valid zone idex, we can remove the extra check for zone iteration. Link: https://lkml.kernel.org/r/20220317234624.23358-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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36c26128 |
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29-Apr-2022 |
Wei Yang <richard.weiyang@gmail.com> |
mm/vmscan: reclaim only affects managed_zones As mentioned in commit 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator") , reclaim only affects managed_zones. Let's adjust the code and comment accordingly. Link: https://lkml.kernel.org/r/20220327024101.10378-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8560cb1a |
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04-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Remove aops->freepage All implementations now use free_folio so we can delete the callers and the method. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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d2329aa0 |
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01-May-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Add free_folio address space operation Include documentation and convert the callers to use ->free_folio as well as ->freepage. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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68189fef |
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30-Apr-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Change try_to_free_buffers() to take a folio All but two of the callers already have a folio; pass a folio into try_to_free_buffers(). This removes the last user of cancel_dirty_page() so remove that wrapper function too. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Jeff Layton <jlayton@kernel.org>
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520f301c |
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17-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Convert is_dirty_writeback() to take a folio Pass a folio instead of a page to aops->is_dirty_writeback(). Convert both implementations and the caller. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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c574bbe9 |
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22-Mar-2022 |
Huang Ying <ying.huang@intel.com> |
NUMA balancing: optimize page placement for memory tiering system With the advent of various new memory types, some machines will have multiple types of memory, e.g. DRAM and PMEM (persistent memory). The memory subsystem of these machines can be called memory tiering system, because the performance of the different types of memory are usually different. In such system, because of the memory accessing pattern changing etc, some pages in the slow memory may become hot globally. So in this patch, the NUMA balancing mechanism is enhanced to optimize the page placement among the different memory types according to hot/cold dynamically. In a typical memory tiering system, there are CPUs, fast memory and slow memory in each physical NUMA node. The CPUs and the fast memory will be put in one logical node (called fast memory node), while the slow memory will be put in another (faked) logical node (called slow memory node). That is, the fast memory is regarded as local while the slow memory is regarded as remote. So it's possible for the recently accessed pages in the slow memory node to be promoted to the fast memory node via the existing NUMA balancing mechanism. The original NUMA balancing mechanism will stop to migrate pages if the free memory of the target node becomes below the high watermark. This is a reasonable policy if there's only one memory type. But this makes the original NUMA balancing mechanism almost do not work to optimize page placement among different memory types. Details are as follows. It's the common cases that the working-set size of the workload is larger than the size of the fast memory nodes. Otherwise, it's unnecessary to use the slow memory at all. So, there are almost always no enough free pages in the fast memory nodes, so that the globally hot pages in the slow memory node cannot be promoted to the fast memory node. To solve the issue, we have 2 choices as follows, a. Ignore the free pages watermark checking when promoting hot pages from the slow memory node to the fast memory node. This will create some memory pressure in the fast memory node, thus trigger the memory reclaiming. So that, the cold pages in the fast memory node will be demoted to the slow memory node. b. Define a new watermark called wmark_promo which is higher than wmark_high, and have kswapd reclaiming pages until free pages reach such watermark. The scenario is as follows: when we want to promote hot-pages from a slow memory to a fast memory, but fast memory's free pages would go lower than high watermark with such promotion, we wake up kswapd with wmark_promo watermark in order to demote cold pages and free us up some space. So, next time we want to promote hot-pages we might have a chance of doing so. The choice "a" may create high memory pressure in the fast memory node. If the memory pressure of the workload is high, the memory pressure may become so high that the memory allocation latency of the workload is influenced, e.g. the direct reclaiming may be triggered. The choice "b" works much better at this aspect. If the memory pressure of the workload is high, the hot pages promotion will stop earlier because its allocation watermark is higher than that of the normal memory allocation. So in this patch, choice "b" is implemented. A new zone watermark (WMARK_PROMO) is added. Which is larger than the high watermark and can be controlled via watermark_scale_factor. In addition to the original page placement optimization among sockets, the NUMA balancing mechanism is extended to be used to optimize page placement according to hot/cold among different memory types. So the sysctl user space interface (numa_balancing) is extended in a backward compatible way as follow, so that the users can enable/disable these functionality individually. The sysctl is converted from a Boolean value to a bits field. The definition of the flags is, - 0: NUMA_BALANCING_DISABLED - 1: NUMA_BALANCING_NORMAL - 2: NUMA_BALANCING_MEMORY_TIERING We have tested the patch with the pmbench memory accessing benchmark with the 80:20 read/write ratio and the Gauss access address distribution on a 2 socket Intel server with Optane DC Persistent Memory Model. The test results shows that the pmbench score can improve up to 95.9%. Thanks Andrew Morton to help fix the document format error. Link: https://lkml.kernel.org/r/20220221084529.1052339-3-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Wei Xu <weixugc@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Feng Tang <feng.tang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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96bd3e79 |
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22-Mar-2022 |
Charan Teja Kalla <quic_charante@quicinc.com> |
mm: vmscan: fix documentation for page_check_references() Commit b518154e59aa ("mm/vmscan: protect the workingset on anonymous LRU") requires to look twice for both mapped anon/file pages are used more than once to take the decission of reclaim or activation. Correct the documentation accordingly. Link: https://lkml.kernel.org/r/1646925640-21324-1-git-send-email-quic_charante@quicinc.com Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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89f6c88a |
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22-Mar-2022 |
Hugh Dickins <hughd@google.com> |
mm: __isolate_lru_page_prepare() in isolate_migratepages_block() __isolate_lru_page_prepare() conflates two unrelated functions, with the flags to one disjoint from the flags to the other; and hides some of the important checks outside of isolate_migratepages_block(), where the sequence is better to be visible. It comes from the days of lumpy reclaim, before compaction, when the combination made more sense. Move what's needed by mm/compaction.c isolate_migratepages_block() inline there, and what's needed by mm/vmscan.c isolate_lru_pages() inline there. Shorten "isolate_mode" to "mode", so the sequence of conditions is easier to read. Declare a "mapping" variable, to save one call to page_mapping() (but not another: calling again after page is locked is necessary). Simplify isolate_lru_pages() with a "move_to" list pointer. Link: https://lkml.kernel.org/r/879d62a8-91cc-d3c6-fb3b-69768236df68@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Alex Shi <alexs@kernel.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b698f0a1 |
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22-Mar-2022 |
Hugh Dickins <hughd@google.com> |
mm/fs: delete PF_SWAPWRITE PF_SWAPWRITE has been redundant since v3.2 commit ee72886d8ed5 ("mm: vmscan: do not writeback filesystem pages in direct reclaim"). Coincidentally, NeilBrown's current patch "remove inode_congested()" deletes may_write_to_inode(), which appeared to be the one function which took notice of PF_SWAPWRITE. But if you study the old logic, and the conditions under which may_write_to_inode() was called, you discover that flag and function have been pointless for a decade. Link: https://lkml.kernel.org/r/75e80e7-742d-e3bd-531-614db8961e4@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Cc: NeilBrown <neilb@suse.de> Cc: Jan Kara <jack@suse.de> Cc: "Darrick J. Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b9b1335e |
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22-Mar-2022 |
NeilBrown <neilb@suse.de> |
remove bdi_congested() and wb_congested() and related functions These functions are no longer useful as no BDIs report congestions any more. Removing the test on bdi_write_contested() in current_may_throttle() could cause a small change in behaviour, but only when PF_LOCAL_THROTTLE is set. So replace the calls by 'false' and simplify the code - and remove the functions. [akpm@linux-foundation.org: fix build] Link: https://lkml.kernel.org/r/164549983742.9187.2570198746005819592.stgit@noble.brown Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nilfs] Cc: Anna Schumaker <Anna.Schumaker@Netapp.com> Cc: Chao Yu <chao@kernel.org> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Layton <jlayton@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Lars Ellenberg <lars.ellenberg@linbit.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Paolo Valente <paolo.valente@linaro.org> Cc: Philipp Reisner <philipp.reisner@linbit.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fe55d563 |
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22-Mar-2022 |
NeilBrown <neilb@suse.de> |
remove inode_congested() inode_congested() reports if the backing-device for the inode is congested. No bdi reports congestion any more, so this always returns 'false'. So remove inode_congested() and related functions, and remove the call sites, assuming that inode_congested() always returns 'false'. Link: https://lkml.kernel.org/r/164549983741.9187.2174285592262191311.stgit@noble.brown Signed-off-by: NeilBrown <neilb@suse.de> Cc: Anna Schumaker <Anna.Schumaker@Netapp.com> Cc: Chao Yu <chao@kernel.org> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Layton <jlayton@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Lars Ellenberg <lars.ellenberg@linbit.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Paolo Valente <paolo.valente@linaro.org> Cc: Philipp Reisner <philipp.reisner@linbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d4b4084a |
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04-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: Turn can_split_huge_page() into can_split_folio() This function already required a head page to be passed, so this just adds type-safety and removes a few implicit calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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e0cd5e7f |
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17-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Convert pageout() to take a folio We always write out an entire folio at once. This conversion removes a few calls to compound_head() and gets the NR_VMSCAN_WRITE statistic right when writing out a large folio. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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d92013d1 |
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15-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Turn page_check_references() into folio_check_references() This function only has one caller, and it already has a folio. This removes a number of calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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c79b7b96 |
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17-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Account large folios correctly The statistics we gather should count the number of pages, not the number of folios. The logic in this function is somewhat convoluted, but even if we split the folio, I think the accounting is now correct. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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343b2888 |
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15-Aug-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Optimise shrink_page_list for non-PMD-sized folios A large folio which is smaller than a PMD does not need to do the extra work in try_to_unmap() of trying to split a PMD entry. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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820c4e2e |
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30-Sep-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Free non-shmem folios without splitting them We have to allocate memory in order to split a file-backed folio, so it's not a good idea to split them in the memory freeing path. It also doesn't work for XFS because pages have an extra reference count from page_has_private() and split_huge_page() expects that reference to have already been removed. Unfortunately, we still have to split shmem THPs because we can't handle swapping out an entire THP yet. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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869f7ee6 |
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15-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/rmap: Convert try_to_unmap() to take a folio Change all three callers and the worker function try_to_unmap_one(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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b3ac0413 |
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21-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/rmap: Turn page_referenced() into folio_referenced() Both its callers pass a page which was previously on an LRU list, so were passing a folio by definition. Use the type system to enforce that and remove a few calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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346cf613 |
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18-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: Add split_folio_to_list() This is a convenience function; split_huge_page_to_list() can take any page in a folio (and does so on purpose because that page will be the one which keeps the refcount). But it's convenient for the callers to pass the folio instead of the first page in the folio. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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e20c41b1 |
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17-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Turn page_check_dirty_writeback() into folio_check_dirty_writeback() Saves a few calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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5100da38 |
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12-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: Convert remove_mapping() to take a folio Add kernel-doc and return the number of pages removed in order to get the statistics right in __invalidate_mapping_pages(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
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be7c07d6 |
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23-Dec-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: Convert __remove_mapping() to take a folio This removes a few hidden calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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ca6d60f3 |
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21-Jan-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: Turn putback_lru_page() into folio_putback_lru() Add a putback_lru_page() wrapper. Removes a couple of compound_head() calls. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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3ecb0087 |
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27-Dec-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/memcg: Convert mem_cgroup_swapout() to take a folio This removes an assumption that THPs are the only kind of compound pages and removes a couple of hidden calls to compound_head. It also documents that you can't pass a tail page to mem_cgroup_swapout(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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8927f647 |
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23-Dec-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/workingset: Convert workingset_eviction() to take a folio This removes an assumption that THPs are the only kind of compound pages and removes a few hidden calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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d1d8a3b4 |
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24-Dec-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: Turn isolate_lru_page() into folio_isolate_lru() Add isolate_lru_page() as a wrapper around isolate_lru_folio(). TestClearPageLRU() would have always failed on a tail page, so returning -EBUSY is the same behaviour. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com>
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47d4f3ee |
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14-Feb-2022 |
Hugh Dickins <hughd@google.com> |
mm/thp: shrink_page_list() avoid splitting VM_LOCKED THP 4.8 commit 7751b2da6be0 ("vmscan: split file huge pages before paging them out") inserted a split_huge_page_to_list() into shrink_page_list() without considering the mlock case: no problem if the page has already been marked as Mlocked (the !page_evictable check much higher up will have skipped all this), but it has always been the case that races or omissions in setting Mlocked can rely on page reclaim to detect this and correct it before actually reclaiming - and that remains so, but what a shame if a hugepage is needlessly split before discovering it. It is surprising that page_check_references() returns PAGEREF_RECLAIM when VM_LOCKED, but there was a good reason for that: try_to_unmap_one() is where the condition is detected and corrected; and until now it could not be done in page_referenced_one(), because that does not always have the page locked. Now that mlock's requirement for page lock has gone, copy try_to_unmap_one()'s mlock restoration into page_referenced_one(), and let page_check_references() return PAGEREF_ACTIVATE in this case. But page_referenced_one() may find a pte mapping one part of a hugepage: what hold should a pte mapped in a VM_LOCKED area exert over the entire huge page? That's debatable. The approach taken here is to treat that pte mapping in page_referenced_one() as if not VM_LOCKED, and if no VM_LOCKED pmd mapping is found later in the walk, and lack of reference permits, then PAGEREF_RECLAIM take it to attempted splitting as before. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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b485c6f1 |
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11-Feb-2022 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: remove deadlock due to throttling failing to make progress A soft lockup bug in kcompactd was reported in a private bugzilla with the following visible in dmesg; watchdog: BUG: soft lockup - CPU#33 stuck for 26s! [kcompactd0:479] watchdog: BUG: soft lockup - CPU#33 stuck for 52s! [kcompactd0:479] watchdog: BUG: soft lockup - CPU#33 stuck for 78s! [kcompactd0:479] watchdog: BUG: soft lockup - CPU#33 stuck for 104s! [kcompactd0:479] The machine had 256G of RAM with no swap and an earlier failed allocation indicated that node 0 where kcompactd was run was potentially unreclaimable; Node 0 active_anon:29355112kB inactive_anon:2913528kB active_file:0kB inactive_file:0kB unevictable:64kB isolated(anon):0kB isolated(file):0kB mapped:8kB dirty:0kB writeback:0kB shmem:26780kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 23480320kB writeback_tmp:0kB kernel_stack:2272kB pagetables:24500kB all_unreclaimable? yes Vlastimil Babka investigated a crash dump and found that a task migrating pages was trying to drain PCP lists; PID: 52922 TASK: ffff969f820e5000 CPU: 19 COMMAND: "kworker/u128:3" Call Trace: __schedule schedule schedule_timeout wait_for_completion __flush_work __drain_all_pages __alloc_pages_slowpath.constprop.114 __alloc_pages alloc_migration_target migrate_pages migrate_to_node do_migrate_pages cpuset_migrate_mm_workfn process_one_work worker_thread kthread ret_from_fork This failure is specific to CONFIG_PREEMPT=n builds. The root of the problem is that kcompact0 is not rescheduling on a CPU while a task that has isolated a large number of the pages from the LRU is waiting on kcompact0 to reschedule so the pages can be released. While shrink_inactive_list() only loops once around too_many_isolated, reclaim can continue without rescheduling if sc->skipped_deactivate == 1 which could happen if there was no file LRU and the inactive anon list was not low. Link: https://lkml.kernel.org/r/20220203100326.GD3301@suse.de Fixes: d818fca1cac3 ("mm/vmscan: throttle reclaim and compaction when too may pages are isolated") Signed-off-by: Mel Gorman <mgorman@suse.de> Debugged-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e4b424b7 |
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14-Jan-2022 |
Gang Li <ligang.bdlg@bytedance.com> |
vmscan: make drop_slab_node static drop_slab_node is only used in drop_slab. So remove it's declaration from header file and add keyword static for it's definition. Link: https://lkml.kernel.org/r/20211111062445.5236-1-ligang.bdlg@bytedance.com Signed-off-by: Gang Li <ligang.bdlg@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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80082938 |
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31-Dec-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm: vmscan: reduce throttling due to a failure to make progress -fix Hugh Dickins reported the following My tmpfs swapping load (tweaked to use huge pages more heavily than in real life) is far from being a realistic load: but it was notably slowed down by your throttling mods in 5.16-rc, and this patch makes it well again - thanks. But: it very quickly hit NULL pointer until I changed that last line to if (first_pgdat) consider_reclaim_throttle(first_pgdat, sc); The likely issue is that huge pages are a major component of the test workload. When this is the case, first_pgdat may never get set if compaction is ready to continue due to this check if (IS_ENABLED(CONFIG_COMPACTION) && sc->order > PAGE_ALLOC_COSTLY_ORDER && compaction_ready(zone, sc)) { sc->compaction_ready = true; continue; } If this was true for every zone in the zonelist, first_pgdat would never get set resulting in a NULL pointer exception. Link: https://lkml.kernel.org/r/20211209095453.GM3366@techsingularity.net Fixes: 1b4e3f26f9f75 ("mm: vmscan: Reduce throttling due to a failure to make progress") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Rik van Riel <riel@surriel.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1b4e3f26 |
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02-Dec-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm: vmscan: Reduce throttling due to a failure to make progress Mike Galbraith, Alexey Avramov and Darrick Wong all reported similar problems due to reclaim throttling for excessive lengths of time. In Alexey's case, a memory hog that should go OOM quickly stalls for several minutes before stalling. In Mike and Darrick's cases, a small memcg environment stalled excessively even though the system had enough memory overall. Commit 69392a403f49 ("mm/vmscan: throttle reclaim when no progress is being made") introduced the problem although commit a19594ca4a8b ("mm/vmscan: increase the timeout if page reclaim is not making progress") made it worse. Systems at or near an OOM state that cannot be recovered must reach OOM quickly and memcg should kill tasks if a memcg is near OOM. To address this, only stall for the first zone in the zonelist, reduce the timeout to 1 tick for VMSCAN_THROTTLE_NOPROGRESS and only stall if the scan control nr_reclaimed is 0, kswapd is still active and there were excessive pages pending for writeback. If kswapd has stopped reclaiming due to excessive failures, do not stall at all so that OOM triggers relatively quickly. Similarly, if an LRU is simply congested, only lightly throttle similar to NOPROGRESS. Alexey's original case was the most straight forward for i in {1..3}; do tail /dev/zero; done On vanilla 5.16-rc1, this test stalled heavily, after the patch the test completes in a few seconds similar to 5.15. Alexey's second test case added watching a youtube video while tail runs 10 times. On 5.15, playback only jitters slightly, 5.16-rc1 stalls a lot with lots of frames missing and numerous audio glitches. With this patch applies, the video plays similarly to 5.15. [lkp@intel.com: Fix W=1 build warning] Link: https://lore.kernel.org/r/99e779783d6c7fce96448a3402061b9dc1b3b602.camel@gmx.de Link: https://lore.kernel.org/r/20211124011954.7cab9bb4@mail.inbox.lv Link: https://lore.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net Link: https://lore.kernel.org/r/20211202150614.22440-1-mgorman@techsingularity.net Link: https://linux-regtracking.leemhuis.info/regzbot/regression/20211124011954.7cab9bb4@mail.inbox.lv/ Reported-and-tested-by: Alexey Avramov <hakavlad@inbox.lv> Reported-and-tested-by: Mike Galbraith <efault@gmx.de> Reported-and-tested-by: Darrick J. Wong <djwong@kernel.org> Reported-by: kernel test robot <lkp@intel.com> Acked-by: Hugh Dickins <hughd@google.com> Tracked-by: Thorsten Leemhuis <regressions@leemhuis.info> Fixes: 69392a403f49 ("mm/vmscan: throttle reclaim when no progress is being made") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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51b8c1fe |
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08-Nov-2021 |
Johannes Weiner <hannes@cmpxchg.org> |
vfs: keep inodes with page cache off the inode shrinker LRU Historically (pre-2.5), the inode shrinker used to reclaim only empty inodes and skip over those that still contained page cache. This caused problems on highmem hosts: struct inode could put fill lowmem zones before the cache was getting reclaimed in the highmem zones. To address this, the inode shrinker started to strip page cache to facilitate reclaiming lowmem. However, this comes with its own set of problems: the shrinkers may drop actively used page cache just because the inodes are not currently open or dirty - think working with a large git tree. It further doesn't respect cgroup memory protection settings and can cause priority inversions between containers. Nowadays, the page cache also holds non-resident info for evicted cache pages in order to detect refaults. We've come to rely heavily on this data inside reclaim for protecting the cache workingset and driving swap behavior. We also use it to quantify and report workload health through psi. The latter in turn is used for fleet health monitoring, as well as driving automated memory sizing of workloads and containers, proactive reclaim and memory offloading schemes. The consequences of dropping page cache prematurely is that we're seeing subtle and not-so-subtle failures in all of the above-mentioned scenarios, with the workload generally entering unexpected thrashing states while losing the ability to reliably detect it. To fix this on non-highmem systems at least, going back to rotating inodes on the LRU isn't feasible. We've tried (commit a76cf1a474d7 ("mm: don't reclaim inodes with many attached pages")) and failed (commit 69056ee6a8a3 ("Revert "mm: don't reclaim inodes with many attached pages"")). The issue is mostly that shrinker pools attract pressure based on their size, and when objects get skipped the shrinkers remember this as deferred reclaim work. This accumulates excessive pressure on the remaining inodes, and we can quickly eat into heavily used ones, or dirty ones that require IO to reclaim, when there potentially is plenty of cold, clean cache around still. Instead, this patch keeps populated inodes off the inode LRU in the first place - just like an open file or dirty state would. An otherwise clean and unused inode then gets queued when the last cache entry disappears. This solves the problem without reintroducing the reclaim issues, and generally is a bit more scalable than having to wade through potentially hundreds of thousands of busy inodes. Locking is a bit tricky because the locks protecting the inode state (i_lock) and the inode LRU (lru_list.lock) don't nest inside the irq-safe page cache lock (i_pages.xa_lock). Page cache deletions are serialized through i_lock, taken before the i_pages lock, to make sure depopulated inodes are queued reliably. Additions may race with deletions, but we'll check again in the shrinker. If additions race with the shrinker itself, we're protected by the i_lock: if find_inode() or iput() win, the shrinker will bail on the elevated i_count or I_REFERENCED; if the shrinker wins and goes ahead with the inode, it will set I_FREEING and inhibit further igets(), which will cause the other side to create a new instance of the inode instead. Link: https://lkml.kernel.org/r/20210614211904.14420-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <guro@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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66ce520b |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: delay waking of tasks throttled on NOPROGRESS Tracing indicates that tasks throttled on NOPROGRESS are woken prematurely resulting in occasional massive spikes in direct reclaim activity. This patch wakes tasks throttled on NOPROGRESS if reclaim efficiency is at least 12%. Link: https://lkml.kernel.org/r/20211022144651.19914-9-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a19594ca |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: increase the timeout if page reclaim is not making progress Tracing of the stutterp workload showed the following delays 1 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=536000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=544000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=556000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=624000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=716000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usect_delayed=772000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usect_delayed=512000 reason=VMSCAN_THROTTLE_NOPROGRESS 16 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS 53 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS 116 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS 5907 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS 71741 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS All the throttling hit the full timeout and then there was wakeup delays meaning that the wakeups are premature as no other reclaimer such as kswapd has made progress. This patch increases the maximum timeout. Link: https://lkml.kernel.org/r/20211022144651.19914-8-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c3f4a9a2 |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: centralise timeout values for reclaim_throttle Neil Brown raised concerns about callers of reclaim_throttle specifying a timeout value. The original timeout values to congestion_wait() were probably pulled out of thin air or copy&pasted from somewhere else. This patch centralises the timeout values and selects a timeout based on the reason for reclaim throttling. These figures are also pulled out of the same thin air but better values may be derived Running a workload that is throttling for inappropriate periods and tracing mm_vmscan_throttled can be used to pick a more appropriate value. Excessive throttling would pick a lower timeout where as excessive CPU usage in reclaim context would select a larger timeout. Ideally a large value would always be used and the wakeups would occur before a timeout but that requires careful testing. Link: https://lkml.kernel.org/r/20211022144651.19914-7-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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69392a40 |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: throttle reclaim when no progress is being made Memcg reclaim throttles on congestion if no reclaim progress is made. This makes little sense, it might be due to writeback or a host of other factors. For !memcg reclaim, it's messy. Direct reclaim primarily is throttled in the page allocator if it is failing to make progress. Kswapd throttles if too many pages are under writeback and marked for immediate reclaim. This patch explicitly throttles if reclaim is failing to make progress. [vbabka@suse.cz: Remove redundant code] Link: https://lkml.kernel.org/r/20211022144651.19914-4-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d818fca1 |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: throttle reclaim and compaction when too may pages are isolated Page reclaim throttles on congestion if too many parallel reclaim instances have isolated too many pages. This makes no sense, excessive parallelisation has nothing to do with writeback or congestion. This patch creates an additional workqueue to sleep on when too many pages are isolated. The throttled tasks are woken when the number of isolated pages is reduced or a timeout occurs. There may be some false positive wakeups for GFP_NOIO/GFP_NOFS callers but the tasks will throttle again if necessary. [shy828301@gmail.com: Wake up from compaction context] [vbabka@suse.cz: Account number of throttled tasks only for writeback] Link: https://lkml.kernel.org/r/20211022144651.19914-3-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8cd7c588 |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: throttle reclaim until some writeback completes if congested Patch series "Remove dependency on congestion_wait in mm/", v5. This series that removes all calls to congestion_wait in mm/ and deletes wait_iff_congested. It's not a clever implementation but congestion_wait has been broken for a long time [1]. Even if congestion throttling worked, it was never a great idea. While excessive dirty/writeback pages at the tail of the LRU is one possibility that reclaim may be slow, there is also the problem of too many pages being isolated and reclaim failing for other reasons (elevated references, too many pages isolated, excessive LRU contention etc). This series replaces the "congestion" throttling with 3 different types. - If there are too many dirty/writeback pages, sleep until a timeout or enough pages get cleaned - If too many pages are isolated, sleep until enough isolated pages are either reclaimed or put back on the LRU - If no progress is being made, direct reclaim tasks sleep until another task makes progress with acceptable efficiency. This was initially tested with a mix of workloads that used to trigger corner cases that no longer work. A new test case was created called "stutterp" (pagereclaim-stutterp-noreaders in mmtests) using a freshly created XFS filesystem. Note that it may be necessary to increase the timeout of ssh if executing remotely as ssh itself can get throttled and the connection may timeout. stutterp varies the number of "worker" processes from 4 up to NR_CPUS*4 to check the impact as the number of direct reclaimers increase. It has four types of worker. - One "anon latency" worker creates small mappings with mmap() and times how long it takes to fault the mapping reading it 4K at a time - X file writers which is fio randomly writing X files where the total size of the files add up to the allowed dirty_ratio. fio is allowed to run for a warmup period to allow some file-backed pages to accumulate. The duration of the warmup is based on the best-case linear write speed of the storage. - Y file readers which is fio randomly reading small files - Z anon memory hogs which continually map (100-dirty_ratio)% of memory - Total estimated WSS = (100+dirty_ration) percentage of memory X+Y+Z+1 == NR_WORKERS varying from 4 up to NR_CPUS*4 The intent is to maximise the total WSS with a mix of file and anon memory where some anonymous memory must be swapped and there is a high likelihood of dirty/writeback pages reaching the end of the LRU. The test can be configured to have no background readers to stress dirty/writeback pages. The results below are based on having zero readers. The short summary of the results is that the series works and stalls until some event occurs but the timeouts may need adjustment. The test results are not broken down by patch as the series should be treated as one block that replaces a broken throttling mechanism with a working one. Finally, three machines were tested but I'm reporting the worst set of results. The other two machines had much better latencies for example. First the results of the "anon latency" latency stutterp 5.15.0-rc1 5.15.0-rc1 vanilla mm-reclaimcongest-v5r4 Amean mmap-4 31.4003 ( 0.00%) 2661.0198 (-8374.52%) Amean mmap-7 38.1641 ( 0.00%) 149.2891 (-291.18%) Amean mmap-12 60.0981 ( 0.00%) 187.8105 (-212.51%) Amean mmap-21 161.2699 ( 0.00%) 213.9107 ( -32.64%) Amean mmap-30 174.5589 ( 0.00%) 377.7548 (-116.41%) Amean mmap-48 8106.8160 ( 0.00%) 1070.5616 ( 86.79%) Stddev mmap-4 41.3455 ( 0.00%) 27573.9676 (-66591.66%) Stddev mmap-7 53.5556 ( 0.00%) 4608.5860 (-8505.23%) Stddev mmap-12 171.3897 ( 0.00%) 5559.4542 (-3143.75%) Stddev mmap-21 1506.6752 ( 0.00%) 5746.2507 (-281.39%) Stddev mmap-30 557.5806 ( 0.00%) 7678.1624 (-1277.05%) Stddev mmap-48 61681.5718 ( 0.00%) 14507.2830 ( 76.48%) Max-90 mmap-4 31.4243 ( 0.00%) 83.1457 (-164.59%) Max-90 mmap-7 41.0410 ( 0.00%) 41.0720 ( -0.08%) Max-90 mmap-12 66.5255 ( 0.00%) 53.9073 ( 18.97%) Max-90 mmap-21 146.7479 ( 0.00%) 105.9540 ( 27.80%) Max-90 mmap-30 193.9513 ( 0.00%) 64.3067 ( 66.84%) Max-90 mmap-48 277.9137 ( 0.00%) 591.0594 (-112.68%) Max mmap-4 1913.8009 ( 0.00%) 299623.9695 (-15555.96%) Max mmap-7 2423.9665 ( 0.00%) 204453.1708 (-8334.65%) Max mmap-12 6845.6573 ( 0.00%) 221090.3366 (-3129.64%) Max mmap-21 56278.6508 ( 0.00%) 213877.3496 (-280.03%) Max mmap-30 19716.2990 ( 0.00%) 216287.6229 (-997.00%) Max mmap-48 477923.9400 ( 0.00%) 245414.8238 ( 48.65%) For most thread counts, the time to mmap() is unfortunately increased. In earlier versions of the series, this was lower but a large number of throttling events were reaching their timeout increasing the amount of inefficient scanning of the LRU. There is no prioritisation of reclaim tasks making progress based on each tasks rate of page allocation versus progress of reclaim. The variance is also impacted for high worker counts but in all cases, the differences in latency are not statistically significant due to very large maximum outliers. Max-90 shows that 90% of the stalls are comparable but the Max results show the massive outliers which are increased to to stalling. It is expected that this will be very machine dependant. Due to the test design, reclaim is difficult so allocations stall and there are variances depending on whether THPs can be allocated or not. The amount of memory will affect exactly how bad the corner cases are and how often they trigger. The warmup period calculation is not ideal as it's based on linear writes where as fio is randomly writing multiple files from multiple tasks so the start state of the test is variable. For example, these are the latencies on a single-socket machine that had more memory Amean mmap-4 42.2287 ( 0.00%) 49.6838 * -17.65%* Amean mmap-7 216.4326 ( 0.00%) 47.4451 * 78.08%* Amean mmap-12 2412.0588 ( 0.00%) 51.7497 ( 97.85%) Amean mmap-21 5546.2548 ( 0.00%) 51.8862 ( 99.06%) Amean mmap-30 1085.3121 ( 0.00%) 72.1004 ( 93.36%) The overall system CPU usage and elapsed time is as follows 5.15.0-rc3 5.15.0-rc3 vanilla mm-reclaimcongest-v5r4 Duration User 6989.03 983.42 Duration System 7308.12 799.68 Duration Elapsed 2277.67 2092.98 The patches reduce system CPU usage by 89% as the vanilla kernel is rarely stalling. The high-level /proc/vmstats show 5.15.0-rc1 5.15.0-rc1 vanilla mm-reclaimcongest-v5r2 Ops Direct pages scanned 1056608451.00 503594991.00 Ops Kswapd pages scanned 109795048.00 147289810.00 Ops Kswapd pages reclaimed 63269243.00 31036005.00 Ops Direct pages reclaimed 10803973.00 6328887.00 Ops Kswapd efficiency % 57.62 21.07 Ops Kswapd velocity 48204.98 57572.86 Ops Direct efficiency % 1.02 1.26 Ops Direct velocity 463898.83 196845.97 Kswapd scanned less pages but the detailed pattern is different. The vanilla kernel scans slowly over time where as the patches exhibits burst patterns of scan activity. Direct reclaim scanning is reduced by 52% due to stalling. The pattern for stealing pages is also slightly different. Both kernels exhibit spikes but the vanilla kernel when reclaiming shows pages being reclaimed over a period of time where as the patches tend to reclaim in spikes. The difference is that vanilla is not throttling and instead scanning constantly finding some pages over time where as the patched kernel throttles and reclaims in spikes. Ops Percentage direct scans 90.59 77.37 For direct reclaim, vanilla scanned 90.59% of pages where as with the patches, 77.37% were direct reclaim due to throttling Ops Page writes by reclaim 2613590.00 1687131.00 Page writes from reclaim context are reduced. Ops Page writes anon 2932752.00 1917048.00 And there is less swapping. Ops Page reclaim immediate 996248528.00 107664764.00 The number of pages encountered at the tail of the LRU tagged for immediate reclaim but still dirty/writeback is reduced by 89%. Ops Slabs scanned 164284.00 153608.00 Slab scan activity is similar. ftrace was used to gather stall activity Vanilla ------- 1 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=16000 2 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=12000 8 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=8000 29 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=4000 82394 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=0 The fast majority of wait_iff_congested calls do not stall at all. What is likely happening is that cond_resched() reschedules the task for a short period when the BDI is not registering congestion (which it never will in this test setup). 1 writeback_congestion_wait: usec_timeout=100000 usec_delayed=120000 2 writeback_congestion_wait: usec_timeout=100000 usec_delayed=132000 4 writeback_congestion_wait: usec_timeout=100000 usec_delayed=112000 380 writeback_congestion_wait: usec_timeout=100000 usec_delayed=108000 778 writeback_congestion_wait: usec_timeout=100000 usec_delayed=104000 congestion_wait if called always exceeds the timeout as there is no trigger to wake it up. Bottom line: Vanilla will throttle but it's not effective. Patch series ------------ Kswapd throttle activity was always due to scanning pages tagged for immediate reclaim at the tail of the LRU 1 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK 4 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK 5 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK 6 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK 11 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK 11 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK 94 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK 112 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK The majority of events did not stall or stalled for a short period. Roughly 16% of stalls reached the timeout before expiry. For direct reclaim, the number of times stalled for each reason were 6624 reason=VMSCAN_THROTTLE_ISOLATED 93246 reason=VMSCAN_THROTTLE_NOPROGRESS 96934 reason=VMSCAN_THROTTLE_WRITEBACK The most common reason to stall was due to excessive pages tagged for immediate reclaim at the tail of the LRU followed by a failure to make forward. A relatively small number were due to too many pages isolated from the LRU by parallel threads For VMSCAN_THROTTLE_ISOLATED, the breakdown of delays was 9 usec_timeout=20000 usect_delayed=4000 reason=VMSCAN_THROTTLE_ISOLATED 12 usec_timeout=20000 usect_delayed=16000 reason=VMSCAN_THROTTLE_ISOLATED 83 usec_timeout=20000 usect_delayed=20000 reason=VMSCAN_THROTTLE_ISOLATED 6520 usec_timeout=20000 usect_delayed=0 reason=VMSCAN_THROTTLE_ISOLATED Most did not stall at all. A small number reached the timeout. For VMSCAN_THROTTLE_NOPROGRESS, the breakdown of stalls were all over the map 1 usec_timeout=500000 usect_delayed=324000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usec_timeout=500000 usect_delayed=332000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usec_timeout=500000 usect_delayed=348000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usec_timeout=500000 usect_delayed=360000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=228000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=260000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=340000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=364000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=372000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=428000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=460000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=464000 reason=VMSCAN_THROTTLE_NOPROGRESS 3 usec_timeout=500000 usect_delayed=244000 reason=VMSCAN_THROTTLE_NOPROGRESS 3 usec_timeout=500000 usect_delayed=252000 reason=VMSCAN_THROTTLE_NOPROGRESS 3 usec_timeout=500000 usect_delayed=272000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=188000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=268000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=328000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=380000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=392000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=432000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=204000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=220000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=412000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=436000 reason=VMSCAN_THROTTLE_NOPROGRESS 6 usec_timeout=500000 usect_delayed=488000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=212000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=300000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=316000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=472000 reason=VMSCAN_THROTTLE_NOPROGRESS 8 usec_timeout=500000 usect_delayed=248000 reason=VMSCAN_THROTTLE_NOPROGRESS 8 usec_timeout=500000 usect_delayed=356000 reason=VMSCAN_THROTTLE_NOPROGRESS 8 usec_timeout=500000 usect_delayed=456000 reason=VMSCAN_THROTTLE_NOPROGRESS 9 usec_timeout=500000 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS 9 usec_timeout=500000 usect_delayed=376000 reason=VMSCAN_THROTTLE_NOPROGRESS 9 usec_timeout=500000 usect_delayed=484000 reason=VMSCAN_THROTTLE_NOPROGRESS 10 usec_timeout=500000 usect_delayed=172000 reason=VMSCAN_THROTTLE_NOPROGRESS 10 usec_timeout=500000 usect_delayed=420000 reason=VMSCAN_THROTTLE_NOPROGRESS 10 usec_timeout=500000 usect_delayed=452000 reason=VMSCAN_THROTTLE_NOPROGRESS 11 usec_timeout=500000 usect_delayed=256000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=144000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=152000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=264000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=384000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=424000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=492000 reason=VMSCAN_THROTTLE_NOPROGRESS 13 usec_timeout=500000 usect_delayed=184000 reason=VMSCAN_THROTTLE_NOPROGRESS 13 usec_timeout=500000 usect_delayed=444000 reason=VMSCAN_THROTTLE_NOPROGRESS 14 usec_timeout=500000 usect_delayed=308000 reason=VMSCAN_THROTTLE_NOPROGRESS 14 usec_timeout=500000 usect_delayed=440000 reason=VMSCAN_THROTTLE_NOPROGRESS 14 usec_timeout=500000 usect_delayed=476000 reason=VMSCAN_THROTTLE_NOPROGRESS 16 usec_timeout=500000 usect_delayed=140000 reason=VMSCAN_THROTTLE_NOPROGRESS 17 usec_timeout=500000 usect_delayed=232000 reason=VMSCAN_THROTTLE_NOPROGRESS 17 usec_timeout=500000 usect_delayed=240000 reason=VMSCAN_THROTTLE_NOPROGRESS 17 usec_timeout=500000 usect_delayed=280000 reason=VMSCAN_THROTTLE_NOPROGRESS 18 usec_timeout=500000 usect_delayed=404000 reason=VMSCAN_THROTTLE_NOPROGRESS 20 usec_timeout=500000 usect_delayed=148000 reason=VMSCAN_THROTTLE_NOPROGRESS 20 usec_timeout=500000 usect_delayed=216000 reason=VMSCAN_THROTTLE_NOPROGRESS 20 usec_timeout=500000 usect_delayed=468000 reason=VMSCAN_THROTTLE_NOPROGRESS 21 usec_timeout=500000 usect_delayed=448000 reason=VMSCAN_THROTTLE_NOPROGRESS 23 usec_timeout=500000 usect_delayed=168000 reason=VMSCAN_THROTTLE_NOPROGRESS 23 usec_timeout=500000 usect_delayed=296000 reason=VMSCAN_THROTTLE_NOPROGRESS 25 usec_timeout=500000 usect_delayed=132000 reason=VMSCAN_THROTTLE_NOPROGRESS 25 usec_timeout=500000 usect_delayed=352000 reason=VMSCAN_THROTTLE_NOPROGRESS 26 usec_timeout=500000 usect_delayed=180000 reason=VMSCAN_THROTTLE_NOPROGRESS 27 usec_timeout=500000 usect_delayed=284000 reason=VMSCAN_THROTTLE_NOPROGRESS 28 usec_timeout=500000 usect_delayed=164000 reason=VMSCAN_THROTTLE_NOPROGRESS 29 usec_timeout=500000 usect_delayed=136000 reason=VMSCAN_THROTTLE_NOPROGRESS 30 usec_timeout=500000 usect_delayed=200000 reason=VMSCAN_THROTTLE_NOPROGRESS 30 usec_timeout=500000 usect_delayed=400000 reason=VMSCAN_THROTTLE_NOPROGRESS 31 usec_timeout=500000 usect_delayed=196000 reason=VMSCAN_THROTTLE_NOPROGRESS 32 usec_timeout=500000 usect_delayed=156000 reason=VMSCAN_THROTTLE_NOPROGRESS 33 usec_timeout=500000 usect_delayed=224000 reason=VMSCAN_THROTTLE_NOPROGRESS 35 usec_timeout=500000 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS 35 usec_timeout=500000 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS 36 usec_timeout=500000 usect_delayed=368000 reason=VMSCAN_THROTTLE_NOPROGRESS 36 usec_timeout=500000 usect_delayed=496000 reason=VMSCAN_THROTTLE_NOPROGRESS 37 usec_timeout=500000 usect_delayed=312000 reason=VMSCAN_THROTTLE_NOPROGRESS 38 usec_timeout=500000 usect_delayed=304000 reason=VMSCAN_THROTTLE_NOPROGRESS 40 usec_timeout=500000 usect_delayed=288000 reason=VMSCAN_THROTTLE_NOPROGRESS 43 usec_timeout=500000 usect_delayed=408000 reason=VMSCAN_THROTTLE_NOPROGRESS 55 usec_timeout=500000 usect_delayed=416000 reason=VMSCAN_THROTTLE_NOPROGRESS 56 usec_timeout=500000 usect_delayed=76000 reason=VMSCAN_THROTTLE_NOPROGRESS 58 usec_timeout=500000 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS 59 usec_timeout=500000 usect_delayed=208000 reason=VMSCAN_THROTTLE_NOPROGRESS 61 usec_timeout=500000 usect_delayed=68000 reason=VMSCAN_THROTTLE_NOPROGRESS 71 usec_timeout=500000 usect_delayed=192000 reason=VMSCAN_THROTTLE_NOPROGRESS 71 usec_timeout=500000 usect_delayed=480000 reason=VMSCAN_THROTTLE_NOPROGRESS 79 usec_timeout=500000 usect_delayed=60000 reason=VMSCAN_THROTTLE_NOPROGRESS 82 usec_timeout=500000 usect_delayed=320000 reason=VMSCAN_THROTTLE_NOPROGRESS 82 usec_timeout=500000 usect_delayed=92000 reason=VMSCAN_THROTTLE_NOPROGRESS 85 usec_timeout=500000 usect_delayed=64000 reason=VMSCAN_THROTTLE_NOPROGRESS 85 usec_timeout=500000 usect_delayed=80000 reason=VMSCAN_THROTTLE_NOPROGRESS 88 usec_timeout=500000 usect_delayed=84000 reason=VMSCAN_THROTTLE_NOPROGRESS 90 usec_timeout=500000 usect_delayed=160000 reason=VMSCAN_THROTTLE_NOPROGRESS 90 usec_timeout=500000 usect_delayed=292000 reason=VMSCAN_THROTTLE_NOPROGRESS 94 usec_timeout=500000 usect_delayed=56000 reason=VMSCAN_THROTTLE_NOPROGRESS 118 usec_timeout=500000 usect_delayed=88000 reason=VMSCAN_THROTTLE_NOPROGRESS 119 usec_timeout=500000 usect_delayed=72000 reason=VMSCAN_THROTTLE_NOPROGRESS 126 usec_timeout=500000 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS 146 usec_timeout=500000 usect_delayed=52000 reason=VMSCAN_THROTTLE_NOPROGRESS 148 usec_timeout=500000 usect_delayed=36000 reason=VMSCAN_THROTTLE_NOPROGRESS 148 usec_timeout=500000 usect_delayed=48000 reason=VMSCAN_THROTTLE_NOPROGRESS 159 usec_timeout=500000 usect_delayed=28000 reason=VMSCAN_THROTTLE_NOPROGRESS 178 usec_timeout=500000 usect_delayed=44000 reason=VMSCAN_THROTTLE_NOPROGRESS 183 usec_timeout=500000 usect_delayed=40000 reason=VMSCAN_THROTTLE_NOPROGRESS 237 usec_timeout=500000 usect_delayed=100000 reason=VMSCAN_THROTTLE_NOPROGRESS 266 usec_timeout=500000 usect_delayed=32000 reason=VMSCAN_THROTTLE_NOPROGRESS 313 usec_timeout=500000 usect_delayed=24000 reason=VMSCAN_THROTTLE_NOPROGRESS 347 usec_timeout=500000 usect_delayed=96000 reason=VMSCAN_THROTTLE_NOPROGRESS 470 usec_timeout=500000 usect_delayed=20000 reason=VMSCAN_THROTTLE_NOPROGRESS 559 usec_timeout=500000 usect_delayed=16000 reason=VMSCAN_THROTTLE_NOPROGRESS 964 usec_timeout=500000 usect_delayed=12000 reason=VMSCAN_THROTTLE_NOPROGRESS 2001 usec_timeout=500000 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS 2447 usec_timeout=500000 usect_delayed=8000 reason=VMSCAN_THROTTLE_NOPROGRESS 7888 usec_timeout=500000 usect_delayed=4000 reason=VMSCAN_THROTTLE_NOPROGRESS 22727 usec_timeout=500000 usect_delayed=0 reason=VMSCAN_THROTTLE_NOPROGRESS 51305 usec_timeout=500000 usect_delayed=500000 reason=VMSCAN_THROTTLE_NOPROGRESS The full timeout is often hit but a large number also do not stall at all. The remainder slept a little allowing other reclaim tasks to make progress. While this timeout could be further increased, it could also negatively impact worst-case behaviour when there is no prioritisation of what task should make progress. For VMSCAN_THROTTLE_WRITEBACK, the breakdown was 1 usec_timeout=100000 usect_delayed=44000 reason=VMSCAN_THROTTLE_WRITEBACK 2 usec_timeout=100000 usect_delayed=76000 reason=VMSCAN_THROTTLE_WRITEBACK 3 usec_timeout=100000 usect_delayed=80000 reason=VMSCAN_THROTTLE_WRITEBACK 5 usec_timeout=100000 usect_delayed=48000 reason=VMSCAN_THROTTLE_WRITEBACK 5 usec_timeout=100000 usect_delayed=84000 reason=VMSCAN_THROTTLE_WRITEBACK 6 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK 7 usec_timeout=100000 usect_delayed=88000 reason=VMSCAN_THROTTLE_WRITEBACK 11 usec_timeout=100000 usect_delayed=56000 reason=VMSCAN_THROTTLE_WRITEBACK 12 usec_timeout=100000 usect_delayed=64000 reason=VMSCAN_THROTTLE_WRITEBACK 16 usec_timeout=100000 usect_delayed=92000 reason=VMSCAN_THROTTLE_WRITEBACK 24 usec_timeout=100000 usect_delayed=68000 reason=VMSCAN_THROTTLE_WRITEBACK 28 usec_timeout=100000 usect_delayed=32000 reason=VMSCAN_THROTTLE_WRITEBACK 30 usec_timeout=100000 usect_delayed=60000 reason=VMSCAN_THROTTLE_WRITEBACK 30 usec_timeout=100000 usect_delayed=96000 reason=VMSCAN_THROTTLE_WRITEBACK 32 usec_timeout=100000 usect_delayed=52000 reason=VMSCAN_THROTTLE_WRITEBACK 42 usec_timeout=100000 usect_delayed=40000 reason=VMSCAN_THROTTLE_WRITEBACK 77 usec_timeout=100000 usect_delayed=28000 reason=VMSCAN_THROTTLE_WRITEBACK 99 usec_timeout=100000 usect_delayed=36000 reason=VMSCAN_THROTTLE_WRITEBACK 137 usec_timeout=100000 usect_delayed=24000 reason=VMSCAN_THROTTLE_WRITEBACK 190 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK 339 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK 518 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK 852 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK 3359 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK 7147 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK 83962 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK The majority hit the timeout in direct reclaim context although a sizable number did not stall at all. This is very different to kswapd where only a tiny percentage of stalls due to writeback reached the timeout. Bottom line, the throttling appears to work and the wakeup events may limit worst case stalls. There might be some grounds for adjusting timeouts but it's likely futile as the worst-case scenarios depend on the workload, memory size and the speed of the storage. A better approach to improve the series further would be to prioritise tasks based on their rate of allocation with the caveat that it may be very expensive to track. This patch (of 5): Page reclaim throttles on wait_iff_congested under the following conditions: - kswapd is encountering pages under writeback and marked for immediate reclaim implying that pages are cycling through the LRU faster than pages can be cleaned. - Direct reclaim will stall if all dirty pages are backed by congested inodes. wait_iff_congested is almost completely broken with few exceptions. This patch adds a new node-based workqueue and tracks the number of throttled tasks and pages written back since throttling started. If enough pages belonging to the node are written back then the throttled tasks will wake early. If not, the throttled tasks sleeps until the timeout expires. [neilb@suse.de: Uninterruptible sleep and simpler wakeups] [hdanton@sina.com: Avoid race when reclaim starts] [vbabka@suse.cz: vmstat irq-safe api, clarifications] Link: https://lore.kernel.org/linux-mm/45d8b7a6-8548-65f5-cccf-9f451d4ae3d4@kernel.dk/ [1] Link: https://lkml.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net Link: https://lkml.kernel.org/r/20211022144651.19914-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: NeilBrown <neilb@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Rik van Riel <riel@surriel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
cb75463c |
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05-Nov-2021 |
Kai Song <songkai01@inspur.com> |
mm/vmscan.c: fix -Wunused-but-set-variable warning We fix the following warning when building kernel with W=1: mm/vmscan.c:1362:6: warning: variable 'err' set but not used [-Wunused-but-set-variable] Link: https://lkml.kernel.org/r/20210924181218.21165-1-songkai01@inspur.com Signed-off-by: Kai Song <songkai01@inspur.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
880121be |
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15-Apr-2021 |
Christian König <ckoenig.leichtzumerken@gmail.com> |
mm/vmscan: add sync_shrinkers function v3 While unplugging a device the TTM shrinker implementation needs a barrier to make sure that all concurrent shrink operations are done and no other CPU is referring to a device specific pool any more. Taking and releasing the shrinker semaphore on the write side after unmapping and freeing all pages from the device pool should make sure that no shrinker is running in paralell. This allows us to avoid the contented mutex in the TTM pool implementation for every alloc/free operation. v2: rework the commit message to make clear why we need this v3: rename the function and add more doc as suggested by Daniel Signed-off-by: Christian König <christian.koenig@amd.com> Acked-by: Huang Rui <ray.huang@amd.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210820120528.81114-2-christian.koenig@amd.com
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#
0de340cb |
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29-Jun-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/memcg: Add folio_lruvec_relock_irq() and folio_lruvec_relock_irqsave() These are the folio equivalents of relock_page_lruvec_irq() and folio_lruvec_relock_irqsave(). Also convert page_matches_lruvec() to folio_matches_lruvec(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
e809c3fe |
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28-Jun-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/memcg: Add folio_lruvec_lock() and similar functions These are the folio equivalents of lock_page_lruvec() and similar functions. Also convert lruvec_memcg_debug() to take a folio. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
32d4f4b7 |
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08-Sep-2021 |
Rik van Riel <riel@surriel.com> |
mm,vmscan: fix divide by zero in get_scan_count Commit f56ce412a59d ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim") introduced a divide by zero corner case when oomd is being used in combination with cgroup memory.low protection. When oomd decides to kill a cgroup, it will force the cgroup memory to be reclaimed after killing the tasks, by writing to the memory.max file for that cgroup, forcing the remaining page cache and reclaimable slab to be reclaimed down to zero. Previously, on cgroups with some memory.low protection that would result in the memory being reclaimed down to the memory.low limit, or likely not at all, having the page cache reclaimed asynchronously later. With f56ce412a59d the oomd write to memory.max tries to reclaim all the way down to zero, which may race with another reclaimer, to the point of ending up with the divide by zero below. This patch implements the obvious fix. Link: https://lkml.kernel.org/r/20210826220149.058089c6@imladris.surriel.com Fixes: f56ce412a59d ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim") Signed-off-by: Rik van Riel <riel@surriel.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Chris Down <chris@chrisdown.name> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1399af7e |
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02-Sep-2021 |
Vlastimil Babka <vbabka@suse.cz> |
mm, vmscan: guarantee drop_slab_node() termination drop_slab_node() is called as part of echo 2>/proc/sys/vm/drop_caches operation. It iterates over all memcgs and calls shrink_slab() which in turn iterates over all slab shrinkers. Freed objects are counted and as long as the total number of freed objects from all memcgs and shrinkers is higher than 10, drop_slab_node() loops for another full memcgs*shrinkers iteration. This arbitrary constant threshold of 10 can result in effectively an infinite loop on a system with large number of memcgs and/or parallel activity that allocates new objects. This has been reported previously by Chunxin Zang [1] and recently by our customer. The previous report [1] has resulted in commit 069c411de40a ("mm/vmscan: fix infinite loop in drop_slab_node") which added a check for signals allowing the user to terminate the command writing to drop_caches. At the time it was also considered to make the threshold grow with each iteration to guarantee termination, but such patch hasn't been formally proposed yet. This patch implements the dynamically growing threshold. At first iteration it's enough to free one object to continue, and this threshold effectively doubles with each iteration. Our customer's feedback was positive. There is always a risk that this change will result on some system in a previously terminating drop_caches operation to terminate sooner and free fewer objects. Ideally the semantics would guarantee freeing all freeable objects that existed at the moment of starting the operation, while not looping forever for newly allocated objects, but that's not feasible to track. In the less ideal solution based on thresholds, arguably the termination guarantee is more important than the exhaustiveness guarantee. If there are reports of large regression wrt being exhaustive, we can tune how fast the threshold grows. [1] https://lore.kernel.org/lkml/20200909152047.27905-1-zangchunxin@bytedance.com/T/#u [vbabka@suse.cz: avoid undefined shift behaviour] Link: https://lkml.kernel.org/r/2f034e6f-a753-550a-f374-e4e23899d3d5@suse.cz Link: https://lkml.kernel.org/r/20210818152239.25502-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Chunxin Zang <zangchunxin@bytedance.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Chris Down <chris@chrisdown.name> Cc: Michal Hocko <mhocko@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2e786d9e |
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02-Sep-2021 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: add 'else' to remove check_pending label We could add 'else' to remove the somewhat odd check_pending label to make code core succinct. Link: https://lkml.kernel.org/r/20210717065911.61497-5-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alex Shi <alexs@kernel.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b87c517a |
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02-Sep-2021 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: remove unneeded return value of kswapd_run() The return value of kswapd_run() is unused now. Clean it up. Link: https://lkml.kernel.org/r/20210717065911.61497-4-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alex Shi <alexs@kernel.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
eaad1ae7 |
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02-Sep-2021 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: remove misleading setting to sc->priority The priority field of sc is used to control how many pages we should scan at once while we always traverse the list to shrink the pages in these functions. So these settings are unneeded and misleading. Link: https://lkml.kernel.org/r/20210717065911.61497-3-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Alex Shi <alexs@kernel.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d17be2d9 |
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02-Sep-2021 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/vmscan: remove the PageDirty check after MADV_FREE pages are page_ref_freezed Patch series "Cleanups for vmscan", v2. This series contains cleanups to remove unneeded return value, misleading setting and so on. Also this remove the PageDirty check after MADV_FREE pages are page_ref_freezed. More details can be found in the respective changelogs. This patch (of 4): If the MADV_FREE pages are redirtied before they could be reclaimed, put the pages back to anonymous LRU list by setting SwapBacked flag and the pages will be reclaimed in normal swapout way. But as Yu Zhao pointed out, "The page has only one reference left, which is from the isolation. After the caller puts the page back on lru and drops the reference, the page will be freed anyway. It doesn't matter which lru it goes." So we don't bother checking PageDirty here. [Yu Zhao's comment is also quoted in the code.] Link: https://lkml.kernel.org/r/20210717065911.61497-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210717065911.61497-2-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alex Shi <alexs@kernel.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
20b51af1 |
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02-Sep-2021 |
Huang Ying <ying.huang@intel.com> |
mm/migrate: add sysfs interface to enable reclaim migration Some method is obviously needed to enable reclaim-based migration. Just like traditional autonuma, there will be some workloads that will benefit like workloads with more "static" configurations where hot pages stay hot and cold pages stay cold. If pages come and go from the hot and cold sets, the benefits of this approach will be more limited. The benefits are truly workload-based and *not* hardware-based. We do not believe that there is a viable threshold where certain hardware configurations should have this mechanism enabled while others do not. To be conservative, earlier work defaulted to disable reclaim- based migration and did not include a mechanism to enable it. This proposes add a new sysfs file /sys/kernel/mm/numa/demotion_enabled as a method to enable it. We are open to any alternative that allows end users to enable this mechanism or disable it if workload harm is detected (just like traditional autonuma). Once this is enabled page demotion may move data to a NUMA node that does not fall into the cpuset of the allocating process. This could be construed to violate the guarantees of cpusets. However, since this is an opt-in mechanism, the assumption is that anyone enabling it is content to relax the guarantees. Link: https://lkml.kernel.org/r/20210721063926.3024591-9-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210715055145.195411-10-ying.huang@intel.com Signed-off-by: Huang Ying <ying.huang@intel.com> Originally-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Zi Yan <ziy@nvidia.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Keith Busch <kbusch@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3a235693 |
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02-Sep-2021 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm/vmscan: never demote for memcg reclaim Global reclaim aims to reduce the amount of memory used on a given node or set of nodes. Migrating pages to another node serves this purpose. memcg reclaim is different. Its goal is to reduce the total memory consumption of the entire memcg, across all nodes. Migration does not assist memcg reclaim because it just moves page contents between nodes rather than actually reducing memory consumption. Link: https://lkml.kernel.org/r/20210715055145.195411-9-ying.huang@intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Yang Shi <yang.shi@linux.alibaba.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a2a36488 |
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02-Sep-2021 |
Keith Busch <kbusch@kernel.org> |
mm/vmscan: Consider anonymous pages without swap Reclaim anonymous pages if a migration path is available now that demotion provides a non-swap recourse for reclaiming anon pages. Note that this check is subtly different from the can_age_anon_pages() checks. This mechanism checks whether a specific page in a specific context can actually be reclaimed, given current swap space and cgroup limits. can_age_anon_pages() is a much simpler and more preliminary check which just says whether there is a possibility of future reclaim. [kbusch@kernel.org: v11] Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210721063926.3024591-7-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2f368a9f |
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02-Sep-2021 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm/vmscan: add helper for querying ability to age anonymous pages Anonymous pages are kept on their own LRU(s). These lists could theoretically always be scanned and maintained. But, without swap, there is currently nothing the kernel can *do* with the results of a scanned, sorted LRU for anonymous pages. A check for '!total_swap_pages' currently serves as a valid check as to whether anonymous LRUs should be maintained. However, another method will be added shortly: page demotion. Abstract out the 'total_swap_pages' checks into a helper, give it a logically significant name, and check for the possibility of page demotion. [dave.hansen@linux.intel.com: v11] Link: https://lkml.kernel.org/r/20210715055145.195411-7-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210721063926.3024591-6-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210715055145.195411-7-ying.huang@intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Greg Thelen <gthelen@google.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Keith Busch <kbusch@kernel.org> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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668e4147 |
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02-Sep-2021 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm/vmscan: add page demotion counter Account the number of demoted pages. Add pgdemote_kswapd and pgdemote_direct VM counters showed in /proc/vmstat. [ daveh: - __count_vm_events() a bit, and made them look at the THP size directly rather than getting data from migrate_pages() ] Link: https://lkml.kernel.org/r/20210721063926.3024591-5-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210715055145.195411-6-ying.huang@intel.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Wei Xu <weixugc@google.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Greg Thelen <gthelen@google.com> Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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26aa2d19 |
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02-Sep-2021 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm/migrate: demote pages during reclaim This is mostly derived from a patch from Yang Shi: https://lore.kernel.org/linux-mm/1560468577-101178-10-git-send-email-yang.shi@linux.alibaba.com/ Add code to the reclaim path (shrink_page_list()) to "demote" data to another NUMA node instead of discarding the data. This always avoids the cost of I/O needed to read the page back in and sometimes avoids the writeout cost when the page is dirty. A second pass through shrink_page_list() will be made if any demotions fail. This essentially falls back to normal reclaim behavior in the case that demotions fail. Previous versions of this patch may have simply failed to reclaim pages which were eligible for demotion but were unable to be demoted in practice. For some cases, for example, MADV_PAGEOUT, the pages are always discarded instead of demoted to follow the kernel API definition. Because MADV_PAGEOUT is defined as freeing specified pages regardless in which tier they are. Note: This just adds the start of infrastructure for migration. It is actually disabled next to the FIXME in migrate_demote_page_ok(). [dave.hansen@linux.intel.com: v11] Link: https://lkml.kernel.org/r/20210715055145.195411-5-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210721063926.3024591-4-ying.huang@intel.com Link: https://lkml.kernel.org/r/20210715055145.195411-5-ying.huang@intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Wei Xu <weixugc@google.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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aa48e47e |
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02-Sep-2021 |
Shakeel Butt <shakeelb@google.com> |
memcg: infrastructure to flush memcg stats At the moment memcg stats are read in four contexts: 1. memcg stat user interfaces 2. dirty throttling 3. page fault 4. memory reclaim Currently the kernel flushes the stats for first two cases. Flushing the stats for remaining two casese may have performance impact. Always flushing the memcg stats on the page fault code path may negatively impacts the performance of the applications. In addition flushing in the memory reclaim code path, though treated as slowpath, can become the source of contention for the global lock taken for stat flushing because when system or memcg is under memory pressure, many tasks may enter the reclaim path. This patch uses following mechanisms to solve these challenges: 1. Periodically flush the stats from root memcg every 2 seconds. This will time limit the out of sync stats. 2. Asynchronously flush the stats after fixed number of stat updates. In the worst case the stat can be out of sync by O(nr_cpus * BATCH) for 2 seconds. 3. For avoiding thundering herd to flush the stats particularly from the memory reclaim context, introduce memcg local spinlock and let only one flusher active at a time. This could have been done through cgroup_rstat_lock lock but that lock is used by other subsystem and for userspace reading memcg stats. So, it is better to keep flushers introduced by this patch decoupled from cgroup_rstat_lock. However we would have to use irqsafe version of rstat flush but that is fine as this code path will be flushing for whole tree and do the work for everyone. No one will be waiting for that worker. [shakeelb@google.com: fix sleep-in-wrong context bug] Link: https://lkml.kernel.org/r/20210716212137.1391164-2-shakeelb@google.com Link: https://lkml.kernel.org/r/20210714013948.270662-2-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Roman Gushchin <guro@fb.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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30472509 |
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02-Sep-2021 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: remove irqsave/restore locking from contexts with irqs enabled The page cache deletion paths all have interrupts enabled, so no need to use irqsafe/irqrestore locking variants. They used to have irqs disabled by the memcg lock added in commit c4843a7593a9 ("memcg: add per cgroup dirty page accounting"), but that has since been replaced by memcg taking the page lock instead, commit 0a31bc97c80c ("mm: memcontrol: rewrite uncharge AP"). Link: https://lkml.kernel.org/r/20210614211904.14420-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4f3eaf45 |
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02-Sep-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: report a more useful address for reclaim acquisition A recent lockdep report included these lines: [ 96.177910] 3 locks held by containerd/770: [ 96.177934] #0: ffff88810815ea28 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x115/0x770 [ 96.177999] #1: ffffffff82915020 (rcu_read_lock){....}-{1:2}, at: get_swap_device+0x33/0x140 [ 96.178057] #2: ffffffff82955ba0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30 While it was not useful to that bug report to know where the reclaim lock had been acquired, it might be useful under other circumstances. Allow the caller of __fs_reclaim_acquire to specify the instruction pointer to use. Link: https://lkml.kernel.org/r/20210719185709.1755149-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Omar Sandoval <osandov@fb.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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57f29762 |
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19-Aug-2021 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: fix missing psi annotation for node_reclaim() In a debugging session the other day, Rik noticed that node_reclaim() was missing memstall annotations. This means we'll miss pressure and lost productivity resulting from reclaim on an overloaded local NUMA node when vm.zone_reclaim_mode is enabled. There haven't been any reports, but that's likely because vm.zone_reclaim_mode hasn't been a commonly used feature recently, and the intersection between such setups and psi users is probably nil. But secondary memory such as CXL-connected DIMMS, persistent memory etc, and the page demotion patches that handle them (https://lore.kernel.org/lkml/20210401183216.443C4443@viggo.jf.intel.com/) could soon make this a more common codepath again. Link: https://lkml.kernel.org/r/20210818152457.35846-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Rik van Riel <riel@surriel.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f56ce412 |
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19-Aug-2021 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim We've noticed occasional OOM killing when memory.low settings are in effect for cgroups. This is unexpected and undesirable as memory.low is supposed to express non-OOMing memory priorities between cgroups. The reason for this is proportional memory.low reclaim. When cgroups are below their memory.low threshold, reclaim passes them over in the first round, and then retries if it couldn't find pages anywhere else. But when cgroups are slightly above their memory.low setting, page scan force is scaled down and diminished in proportion to the overage, to the point where it can cause reclaim to fail as well - only in that case we currently don't retry, and instead trigger OOM. To fix this, hook proportional reclaim into the same retry logic we have in place for when cgroups are skipped entirely. This way if reclaim fails and some cgroups were scanned with diminished pressure, we'll try another full-force cycle before giving up and OOMing. [akpm@linux-foundation.org: coding-style fixes] Link: https://lkml.kernel.org/r/20210817180506.220056-1-hannes@cmpxchg.org Fixes: 9783aa9917f8 ("mm, memcg: proportional memory.{low,min} reclaim") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Leon Yang <lnyng@fb.com> Reviewed-by: Rik van Riel <riel@surriel.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Chris Down <chris@chrisdown.name> Acked-by: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> [5.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f611fab7 |
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30-Jun-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: remove kerneldoc-like comment from isolate_lru_pages Patch series "Clean W=1 build warnings for mm/". This is a janitorial only. During development of a tool to catch build warnings early to avoid tripping the Intel lkp-robot, I noticed that mm/ is not clean for W=1. This is generally harmless but there is no harm in cleaning it up. It disrupts git blame a little but on relatively obvious lines that are unlikely to be git blame targets. This patch (of 13): make W=1 generates the following warning for vmscan.c mm/vmscan.c:1814: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst It is not a kerneldoc comment and isolate_lru_pages() is a static function. While the detailed comment is nice, it does not need to be exposed via kernel-doc. Link: https://lkml.kernel.org/r/20210520084809.8576-1-mgorman@techsingularity.net Link: https://lkml.kernel.org/r/20210520084809.8576-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1fb08ac6 |
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30-Jun-2021 |
Yang Shi <shy828301@gmail.com> |
mm: rmap: make try_to_unmap() void function Currently try_to_unmap() return bool value by checking page_mapcount(), however this may return false positive since page_mapcount() doesn't check all subpages of compound page. The total_mapcount() could be used instead, but its cost is higher since it traverses all subpages. Actually the most callers of try_to_unmap() don't care about the return value at all. So just need check if page is still mapped by page_mapped() when necessary. And page_mapped() does bail out early when it finds mapped subpage. Link: https://lkml.kernel.org/r/bb27e3fe-6036-b637-5086-272befbfe3da@google.com Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jue Wang <juew@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Wang Yugui <wangyugui@e16-tech.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2d2b8d2b |
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30-Jun-2021 |
Yu Zhao <yuzhao@google.com> |
mm/vmscan.c: fix potential deadlock in reclaim_pages() Theoretically without the protect from memalloc_noreclaim_save() and memalloc_noreclaim_restore(), reclaim_pages() can go into the block I/O layer recursively and deadlock. Querying 'reclaim_pages' in our kernel crash databases didn't yield any results. So the deadlock seems unlikely to happen. A possible explanation is that the only user of reclaim_pages(), i.e., MADV_PAGEOUT, is usually called before memory pressure builds up, e.g., on Android and Chrome OS. Under such a condition, allocations in the block I/O layer can be fulfilled without diverting to direct reclaim and therefore the recursion is avoided. Link: https://lkml.kernel.org/r/20210622074642.785473-1-yuzhao@google.com Link: https://lkml.kernel.org/r/20210614194727.2684053-1-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c49c2c47 |
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28-Jun-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/page_alloc: limit the number of pages on PCP lists when reclaim is active When kswapd is active then direct reclaim is potentially active. In either case, it is possible that a zone would be balanced if pages were not trapped on PCP lists. Instead of draining remote pages, simply limit the size of the PCP lists while kswapd is active. Link: https://lkml.kernel.org/r/20210525080119.5455-6-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9ef56b78 |
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28-Jun-2021 |
Muchun Song <songmuchun@bytedance.com> |
mm: vmscan: remove noinline_for_stack The noinline_for_stack is introduced by commit 666356297ec4 ("vmscan: set up pagevec as late as possible in shrink_inactive_list()"), its purpose is to delay the allocation of pagevec as late as possible to save stack memory. But the commit 2bcf88796381 ("mm: take pagevecs off reclaim stack") replace pagevecs by lists of pages_to_free. So we do not need noinline_for_stack, just remove it (let the compiler decide whether to inline). Link: https://lkml.kernel.org/r/20210417043538.9793-9-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7467c391 |
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28-Jun-2021 |
Muchun Song <songmuchun@bytedance.com> |
mm: memcontrol: rename lruvec_holds_page_lru_lock to page_matches_lruvec lruvec_holds_page_lru_lock() doesn't check anything about locking and is used to check whether the page belongs to the lruvec. So rename it to page_matches_lruvec(). Link: https://lkml.kernel.org/r/20210417043538.9793-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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68d68ff6 |
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04-May-2021 |
Zhiyuan Dai <daizhiyuan@phytium.com.cn> |
mm/mempool: minor coding style tweaks Various coding style tweaks to various files under mm/ [daizhiyuan@phytium.com.cn: mm/swapfile: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614223624-16055-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/sparse: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614227288-19363-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/vmscan: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614227649-19853-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/compaction: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614228218-20770-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/oom_kill: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614228360-21168-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/shmem: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614228504-21491-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/page_alloc: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614228613-21754-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/filemap: minor coding style tweaks] Link: https://lkml.kernel.org/r/1614228936-22337-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/mlock: minor coding style tweaks] Link: https://lkml.kernel.org/r/1613956588-2453-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/frontswap: minor coding style tweaks] Link: https://lkml.kernel.org/r/1613962668-15045-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/vmalloc: minor coding style tweaks] Link: https://lkml.kernel.org/r/1613963379-15988-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/memory_hotplug: minor coding style tweaks] Link: https://lkml.kernel.org/r/1613971784-24878-1-git-send-email-daizhiyuan@phytium.com.cn [daizhiyuan@phytium.com.cn: mm/mempolicy: minor coding style tweaks] Link: https://lkml.kernel.org/r/1613972228-25501-1-git-send-email-daizhiyuan@phytium.com.cn Link: https://lkml.kernel.org/r/1614222374-13805-1-git-send-email-daizhiyuan@phytium.com.cn Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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18bb473e |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: shrink deferred objects proportional to priority The number of deferred objects might get windup to an absurd number, and it results in clamp of slab objects. It is undesirable for sustaining workingset. So shrink deferred objects proportional to priority and cap nr_deferred to twice of cache items. The idea is borrowed from Dave Chinner's patch: https://lore.kernel.org/linux-xfs/20191031234618.15403-13-david@fromorbit.com/ Tested with kernel build and vfs metadata heavy workload in our production environment, no regression is spotted so far. Link: https://lkml.kernel.org/r/20210311190845.9708-14-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a178015c |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: memcontrol: reparent nr_deferred when memcg offline Now shrinker's nr_deferred is per memcg for memcg aware shrinkers, add to parent's corresponding nr_deferred when memcg offline. Link: https://lkml.kernel.org/r/20210311190845.9708-13-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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476b30a0 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: don't need allocate shrinker->nr_deferred for memcg aware shrinkers Now nr_deferred is available on per memcg level for memcg aware shrinkers, so don't need allocate shrinker->nr_deferred for such shrinkers anymore. The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or memcg is disabled by kernel command line, then shrinker's SHRINKER_MEMCG_AWARE flag would be cleared. This makes the implementation of this patch simpler. Link: https://lkml.kernel.org/r/20210311190845.9708-12-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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86750830 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: use per memcg nr_deferred of shrinker Use per memcg's nr_deferred for memcg aware shrinkers. The shrinker's nr_deferred will be used in the following cases: 1. Non memcg aware shrinkers 2. !CONFIG_MEMCG 3. memcg is disabled by boot parameter Link: https://lkml.kernel.org/r/20210311190845.9708-11-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3c6f17e6 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: add per memcg shrinker nr_deferred Currently the number of deferred objects are per shrinker, but some slabs, for example, vfs inode/dentry cache are per memcg, this would result in poor isolation among memcgs. The deferred objects typically are generated by __GFP_NOFS allocations, one memcg with excessive __GFP_NOFS allocations may blow up deferred objects, then other innocent memcgs may suffer from over shrink, excessive reclaim latency, etc. For example, two workloads run in memcgA and memcgB respectively, workload in B is vfs heavy workload. Workload in A generates excessive deferred objects, then B's vfs cache might be hit heavily (drop half of caches) by B's limit reclaim or global reclaim. We observed this hit in our production environment which was running vfs heavy workload shown as the below tracing log: <...>-409454 [016] .... 28286961.747146: mm_shrink_slab_start: super_cache_scan+0x0/0x1a0 ffff9a83046f3458: nid: 1 objects to shrink 3641681686040 gfp_flags GFP_HIGHUSER_MOVABLE|__GFP_ZERO pgs_scanned 1 lru_pgs 15721 cache items 246404277 delta 31345 total_scan 123202138 <...>-409454 [022] .... 28287105.928018: mm_shrink_slab_end: super_cache_scan+0x0/0x1a0 ffff9a83046f3458: nid: 1 unused scan count 3641681686040 new scan count 3641798379189 total_scan 602 last shrinker return val 123186855 The vfs cache and page cache ratio was 10:1 on this machine, and half of caches were dropped. This also resulted in significant amount of page caches were dropped due to inodes eviction. Make nr_deferred per memcg for memcg aware shrinkers would solve the unfairness and bring better isolation. The following patch will add nr_deferred to parent memcg when memcg offline. To preserve nr_deferred when reparenting memcgs to root, root memcg needs shrinker_info allocated too. When memcg is not enabled (!CONFIG_MEMCG or memcg disabled), the shrinker's nr_deferred would be used. And non memcg aware shrinkers use shrinker's nr_deferred all the time. Link: https://lkml.kernel.org/r/20210311190845.9708-10-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
41ca668a |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: use a new flag to indicate shrinker is registered Currently registered shrinker is indicated by non-NULL shrinker->nr_deferred. This approach is fine with nr_deferred at the shrinker level, but the following patches will move MEMCG_AWARE shrinkers' nr_deferred to memcg level, so their shrinker->nr_deferred would always be NULL. This would prevent the shrinkers from unregistering correctly. Remove SHRINKER_REGISTERING since we could check if shrinker is registered successfully by the new flag. Link: https://lkml.kernel.org/r/20210311190845.9708-9-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
468ab843 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: add shrinker_info_protected() helper The shrinker_info is dereferenced in a couple of places via rcu_dereference_protected with different calling conventions, for example, using mem_cgroup_nodeinfo helper or dereferencing memcg->nodeinfo[nid]->shrinker_info. And the later patch will add more dereference places. So extract the dereference into a helper to make the code more readable. No functional change. [akpm@linux-foundation.org: retain rcu_dereference_protected() in free_shrinker_info(), per Hugh] Link: https://lkml.kernel.org/r/20210311190845.9708-8-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e4262c4f |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: memcontrol: rename shrinker_map to shrinker_info The following patch is going to add nr_deferred into shrinker_map, the change will make shrinker_map not only include map anymore, so rename it to "memcg_shrinker_info". And this should make the patch adding nr_deferred cleaner and readable and make review easier. Also remove the "memcg_" prefix. Link: https://lkml.kernel.org/r/20210311190845.9708-7-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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72673e86 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: use kvfree_rcu instead of call_rcu Using kvfree_rcu() to free the old shrinker_maps instead of call_rcu(). We don't have to define a dedicated callback for call_rcu() anymore. Link: https://lkml.kernel.org/r/20210311190845.9708-6-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a2fb1261 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: remove memcg_shrinker_map_size Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both. Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the bit map. Link: https://lkml.kernel.org/r/20210311190845.9708-5-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d27cf2aa |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: use shrinker_rwsem to protect shrinker_maps allocation Since memcg_shrinker_map_size just can be changed under holding shrinker_rwsem exclusively, the read side can be protected by holding read lock, so it sounds superfluous to have a dedicated mutex. Kirill Tkhai suggested use write lock since: * We want the assignment to shrinker_maps is visible for shrink_slab_memcg(). * The rcu_dereference_protected() dereferrencing in shrink_slab_memcg(), but in case of we use READ lock in alloc_shrinker_maps(), the dereferrencing is not actually protected. * READ lock makes alloc_shrinker_info() racy against memory allocation fail. alloc_shrinker_info()->free_shrinker_info() may free memory right after shrink_slab_memcg() dereferenced it. You may say shrink_slab_memcg()->mem_cgroup_online() protects us from it? Yes, sure, but this is not the thing we want to remember in the future, since this spreads modularity. And a test with heavy paging workload didn't show write lock makes things worse. Link: https://lkml.kernel.org/r/20210311190845.9708-4-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2bfd3637 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: consolidate shrinker_maps handling code The shrinker map management is not purely memcg specific, it is at the intersection between memory cgroup and shrinkers. It's allocation and assignment of a structure, and the only memcg bit is the map is being stored in a memcg structure. So move the shrinker_maps handling code into vmscan.c for tighter integration with shrinker code, and remove the "memcg_" prefix. There is no functional change. Link: https://lkml.kernel.org/r/20210311190845.9708-3-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8efb4b59 |
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04-May-2021 |
Yang Shi <shy828301@gmail.com> |
mm: vmscan: use nid from shrink_control for tracepoint Patch series "Make shrinker's nr_deferred memcg aware", v10. Recently huge amount one-off slab drop was seen on some vfs metadata heavy workloads, it turned out there were huge amount accumulated nr_deferred objects seen by the shrinker. On our production machine, I saw absurd number of nr_deferred shown as the below tracing result: <...>-48776 [032] .... 27970562.458916: mm_shrink_slab_start: super_cache_scan+0x0/0x1a0 ffff9a83046f3458: nid: 0 objects to shrink 2531805877005 gfp_flags GFP_HIGHUSER_MOVABLE pgs_scanned 32 lru_pgs 9300 cache items 1667 delta 11 total_scan 833 There are 2.5 trillion deferred objects on one node, assuming all of them are dentry (192 bytes per object), so the total size of deferred on one node is ~480TB. It is definitely ridiculous. I managed to reproduce this problem with kernel build workload plus negative dentry generator. First step, run the below kernel build test script: NR_CPUS=`cat /proc/cpuinfo | grep -e processor | wc -l` cd /root/Buildarea/linux-stable for i in `seq 1500`; do cgcreate -g memory:kern_build echo 4G > /sys/fs/cgroup/memory/kern_build/memory.limit_in_bytes echo 3 > /proc/sys/vm/drop_caches cgexec -g memory:kern_build make clean > /dev/null 2>&1 cgexec -g memory:kern_build make -j$NR_CPUS > /dev/null 2>&1 cgdelete -g memory:kern_build done Then run the below negative dentry generator script: NR_CPUS=`cat /proc/cpuinfo | grep -e processor | wc -l` mkdir /sys/fs/cgroup/memory/test echo $$ > /sys/fs/cgroup/memory/test/tasks for i in `seq $NR_CPUS`; do while true; do FILE=`head /dev/urandom | tr -dc A-Za-z0-9 | head -c 64` cat $FILE 2>/dev/null done & done Then kswapd will shrink half of dentry cache in just one loop as the below tracing result showed: kswapd0-475 [028] .... 305968.252561: mm_shrink_slab_start: super_cache_scan+0x0/0x190 0000000024acf00c: nid: 0 objects to shrink 4994376020 gfp_flags GFP_KERNEL cache items 93689873 delta 45746 total_scan 46844936 priority 12 kswapd0-475 [021] .... 306013.099399: mm_shrink_slab_end: super_cache_scan+0x0/0x190 0000000024acf00c: nid: 0 unused scan count 4994376020 new scan count 4947576838 total_scan 8 last shrinker return val 46844928 There were huge number of deferred objects before the shrinker was called, the behavior does match the code but it might be not desirable from the user's stand of point. The excessive amount of nr_deferred might be accumulated due to various reasons, for example: * GFP_NOFS allocation * Significant times of small amount scan (< scan_batch, 1024 for vfs metadata) However the LRUs of slabs are per memcg (memcg-aware shrinkers) but the deferred objects is per shrinker, this may have some bad effects: * Poor isolation among memcgs. Some memcgs which happen to have frequent limit reclaim may get nr_deferred accumulated to a huge number, then other innocent memcgs may take the fall. In our case the main workload was hit. * Unbounded deferred objects. There is no cap for deferred objects, it can outgrow ridiculously as the tracing result showed. * Easy to get out of control. Although shrinkers take into account deferred objects, but it can go out of control easily. One misconfigured memcg could incur absurd amount of deferred objects in a period of time. * Sort of reclaim problems, i.e. over reclaim, long reclaim latency, etc. There may be hundred GB slab caches for vfe metadata heavy workload, shrink half of them may take minutes. We observed latency spike due to the prolonged reclaim. These issues also have been discussed in https://lore.kernel.org/linux-mm/20200916185823.5347-1-shy828301@gmail.com/. The patchset is the outcome of that discussion. So this patchset makes nr_deferred per-memcg to tackle the problem. It does: * Have memcg_shrinker_deferred per memcg per node, just like what shrinker_map does. Instead it is an atomic_long_t array, each element represent one shrinker even though the shrinker is not memcg aware, this simplifies the implementation. For memcg aware shrinkers, the deferred objects are just accumulated to its own memcg. The shrinkers just see nr_deferred from its own memcg. Non memcg aware shrinkers still use global nr_deferred from struct shrinker. * Once the memcg is offlined, its nr_deferred will be reparented to its parent along with LRUs. * The root memcg has memcg_shrinker_deferred array too. It simplifies the handling of reparenting to root memcg. * Cap nr_deferred to 2x of the length of lru. The idea is borrowed from Dave Chinner's series (https://lore.kernel.org/linux-xfs/20191031234618.15403-1-david@fromorbit.com/) The downside is each memcg has to allocate extra memory to store the nr_deferred array. On our production environment, there are typically around 40 shrinkers, so each memcg needs ~320 bytes. 10K memcgs would need ~3.2MB memory. It seems fine. We have been running the patched kernel on some hosts of our fleet (test and production) for months, it works very well. The monitor data shows the working set is sustained as expected. This patch (of 13): The tracepoint's nid should show what node the shrink happens on, the start tracepoint uses nid from shrinkctl, but the nid might be set to 0 before end tracepoint if the shrinker is not NUMA aware, so the tracing log may show the shrink happens on one node but end up on the other node. It seems confusing. And the following patch will remove using nid directly in do_shrink_slab(), this patch also helps cleanup the code. Link: https://lkml.kernel.org/r/20210311190845.9708-1-shy828301@gmail.com Link: https://lkml.kernel.org/r/20210311190845.9708-2-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b6676de8 |
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04-May-2021 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm/vmscan: move RECLAIM* bits to uapi header It is currently not obvious that the RECLAIM_* bits are part of the uapi since they are defined in vmscan.c. Move them to a uapi header to make it obvious. This should have no functional impact. Link: https://lkml.kernel.org/r/20210219172557.08074910@viggo.jf.intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Ben Widawsky <ben.widawsky@intel.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Daniel Wagner <dwagner@suse.de> Cc: "Tobin C. Harding" <tobin@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ae37c7ff |
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04-May-2021 |
Oscar Salvador <osalvador@suse.de> |
mm: make alloc_contig_range handle in-use hugetlb pages alloc_contig_range() will fail if it finds a HugeTLB page within the range, without a chance to handle them. Since HugeTLB pages can be migrated as any LRU or Movable page, it does not make sense to bail out without trying. Enable the interface to recognize in-use HugeTLB pages so we can migrate them, and have much better chances to succeed the call. Link: https://lkml.kernel.org/r/20210419075413.1064-7-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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51998364 |
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24-Feb-2021 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm/vmscan: restore zone_reclaim_mode ABI I went to go add a new RECLAIM_* mode for the zone_reclaim_mode sysctl. Like a good kernel developer, I also went to go update the documentation. I noticed that the bits in the documentation didn't match the bits in the #defines. The VM never explicitly checks the RECLAIM_ZONE bit. The bit is, however implicitly checked when checking 'node_reclaim_mode==0'. The RECLAIM_ZONE #define was removed in a cleanup. That, by itself is fine. But, when the bit was removed (bit 0) the _other_ bit locations also got changed. That's not OK because the bit values are documented to mean one specific thing. Users surely do not expect the meaning to change from kernel to kernel. The end result is that if someone had a script that did: sysctl vm.zone_reclaim_mode=1 it would have gone from enabling node reclaim for clean unmapped pages to writing out pages during node reclaim after the commit in question. That's not great. Put the bits back the way they were and add a comment so something like this is a bit harder to do again. Update the documentation to make it clear that the first bit is ignored. Link: https://lkml.kernel.org/r/20210219172555.FF0CDF23@viggo.jf.intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Fixes: 648b5cf368e0 ("mm/vmscan: remove unused RECLAIM_OFF/RECLAIM_ZONE") Reviewed-by: Ben Widawsky <ben.widawsky@intel.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Daniel Wagner <dwagner@suse.de> Cc: "Tobin C. Harding" <tobin@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Qian Cai <cai@lca.pw> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2091339d |
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24-Feb-2021 |
Yu Zhao <yuzhao@google.com> |
mm/vmscan.c: make lruvec_lru_size() static All other references to the function were removed after commit b910718a948a ("mm: vmscan: detect file thrashing at the reclaim root"). Link: https://lore.kernel.org/linux-mm/20201207220949.830352-11-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-11-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bc711271 |
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24-Feb-2021 |
Yu Zhao <yuzhao@google.com> |
mm: VM_BUG_ON lru page flags Move scattered VM_BUG_ONs to two essential places that cover all lru list additions and deletions. Link: https://lore.kernel.org/linux-mm/20201207220949.830352-8-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-8-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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87560179 |
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24-Feb-2021 |
Yu Zhao <yuzhao@google.com> |
mm: add __clear_page_lru_flags() to replace page_off_lru() Similar to page_off_lru(), the new function does non-atomic clearing of PageLRU() in addition to PageActive() and PageUnevictable(), on a page that has no references left. If PageActive() and PageUnevictable() are both set, refuse to clear either and leave them to bad_page(). This is a behavior change that is meant to help debug. Link: https://lore.kernel.org/linux-mm/20201207220949.830352-7-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-7-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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46ae6b2c |
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24-Feb-2021 |
Yu Zhao <yuzhao@google.com> |
mm/swap.c: don't pass "enum lru_list" to del_page_from_lru_list() The parameter is redundant in the sense that it can be potentially extracted from the "struct page" parameter by page_lru(). We need to make sure that existing PageActive() or PageUnevictable() remains until the function returns. A few places don't conform, and simple reordering fixes them. This patch may have left page_off_lru() seemingly odd, and we'll take care of it in the next patch. Link: https://lore.kernel.org/linux-mm/20201207220949.830352-6-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-6-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3a9c9788 |
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24-Feb-2021 |
Yu Zhao <yuzhao@google.com> |
mm: don't pass "enum lru_list" to lru list addition functions The "enum lru_list" parameter to add_page_to_lru_list() and add_page_to_lru_list_tail() is redundant in the sense that it can be extracted from the "struct page" parameter by page_lru(). A caveat is that we need to make sure PageActive() or PageUnevictable() is correctly set or cleared before calling these two functions. And they are indeed. Link: https://lore.kernel.org/linux-mm/20201207220949.830352-4-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-4-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
42895ea7 |
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24-Feb-2021 |
Yu Zhao <yuzhao@google.com> |
mm/vmscan.c: use add_page_to_lru_list() Patch series "mm: lru related cleanups", v2. The cleanups are intended to reduce the verbosity in lru list operations and make them less error-prone. A typical example would be how the patches change __activate_page(): static void __activate_page(struct page *page, struct lruvec *lruvec) { if (!PageActive(page) && !PageUnevictable(page)) { - int lru = page_lru_base_type(page); int nr_pages = thp_nr_pages(page); - del_page_from_lru_list(page, lruvec, lru); + del_page_from_lru_list(page, lruvec); SetPageActive(page); - lru += LRU_ACTIVE; - add_page_to_lru_list(page, lruvec, lru); + add_page_to_lru_list(page, lruvec); trace_mm_lru_activate(page); There are a few more places like __activate_page() and they are unnecessarily repetitive in terms of figuring out which list a page should be added onto or deleted from. And with the duplicated code removed, they are easier to read, IMO. Patch 1 to 5 basically cover the above. Patch 6 and 7 make code more robust by improving bug reporting. Patch 8, 9 and 10 take care of some dangling helpers left in header files. This patch (of 10): There is add_page_to_lru_list(), and move_pages_to_lru() should reuse it, not duplicate it. Link: https://lkml.kernel.org/r/20210122220600.906146-1-yuzhao@google.com Link: https://lore.kernel.org/linux-mm/20201207220949.830352-2-yuzhao@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-2-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Roman Gushchin <guro@fb.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c2135f7c |
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24-Feb-2021 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/vmscan: __isolate_lru_page_prepare() cleanup The function just returns 2 results, so using a 'switch' to deal with its result is unnecessary. Also simplify it to a bool func as Vlastimil suggested. Also remove 'goto' by reusing list_move(), and take Matthew Wilcox's suggestion to update comments in function. Link: https://lkml.kernel.org/r/728874d7-2d93-4049-68c1-dcc3b2d52ccd@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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feb889fb |
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16-Jan-2021 |
Linus Torvalds <torvalds@linux-foundation.org> |
mm: don't put pinned pages into the swap cache So technically there is nothing wrong with adding a pinned page to the swap cache, but the pinning obviously means that the page can't actually be free'd right now anyway, so it's a bit pointless. However, the real problem is not with it being a bit pointless: the real issue is that after we've added it to the swap cache, we'll try to unmap the page. That will succeed, because the code in mm/rmap.c doesn't know or care about pinned pages. Even the unmapping isn't fatal per se, since the page will stay around in memory due to the pinning, and we do hold the connection to it using the swap cache. But when we then touch it next and take a page fault, the logic in do_swap_page() will map it back into the process as a possibly read-only page, and we'll then break the page association on the next COW fault. Honestly, this issue could have been fixed in any of those other places: (a) we could refuse to unmap a pinned page (which makes conceptual sense), or (b) we could make sure to re-map a pinned page writably in do_swap_page(), or (c) we could just make do_wp_page() not COW the pinned page (which was what we historically did before that "mm: do_wp_page() simplification" commit). But while all of them are equally valid models for breaking this chain, not putting pinned pages into the swap cache in the first place is the simplest one by far. It's also the safest one: the reason why do_wp_page() was changed in the first place was that getting the "can I re-use this page" wrong is so fraught with errors. If you do it wrong, you end up with an incorrectly shared page. As a result, using "page_maybe_dma_pinned()" in either do_wp_page() or do_swap_page() would be a serious bug since it is only a (very good) heuristic. Re-using the page requires a hard black-and-white rule with no room for ambiguity. In contrast, saying "this page is very likely dma pinned, so let's not add it to the swap cache and try to unmap it" is an obviously safe thing to do, and if the heuristic might very rarely be a false positive, no harm is done. Fixes: 09854ba94c6a ("mm: do_wp_page() simplification") Reported-and-tested-by: Martin Raiber <martin@urbackup.org> Cc: Pavel Begunkov <asml.silence@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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15b44736 |
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15-Dec-2020 |
Hugh Dickins <hughd@google.com> |
mm/lru: revise the comments of lru_lock Since we changed the pgdat->lru_lock to lruvec->lru_lock, it's time to fix the incorrect comments in code. Also fixed some zone->lru_lock comment error from ancient time. etc. I struggled to understand the comment above move_pages_to_lru() (surely it never calls page_referenced()), and eventually realized that most of it had got separated from shrink_active_list(): move that comment back. Link: https://lkml.kernel.org/r/1604566549-62481-20-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Jann Horn <jannh@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2a5e4e34 |
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15-Dec-2020 |
Alexander Duyck <alexander.h.duyck@linux.intel.com> |
mm/lru: introduce relock_page_lruvec() Add relock_page_lruvec() to replace repeated same code, no functional change. When testing for relock we can avoid the need for RCU locking if we simply compare the page pgdat and memcg pointers versus those that the lruvec is holding. By doing this we can avoid the extra pointer walks and accesses of the memory cgroup. In addition we can avoid the checks entirely if lruvec is currently NULL. [alex.shi@linux.alibaba.com: use page_memcg()] Link: https://lkml.kernel.org/r/66d8e79d-7ec6-bfbc-1c82-bf32db3ae5b7@linux.alibaba.com Link: https://lkml.kernel.org/r/1604566549-62481-19-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Tejun Heo <tj@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
6168d0da |
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15-Dec-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/lru: replace pgdat lru_lock with lruvec lock This patch moves per node lru_lock into lruvec, thus bring a lru_lock for each of memcg per node. So on a large machine, each of memcg don't have to suffer from per node pgdat->lru_lock competition. They could go fast with their self lru_lock. After move memcg charge before lru inserting, page isolation could serialize page's memcg, then per memcg lruvec lock is stable and could replace per node lru lock. In isolate_migratepages_block(), compact_unlock_should_abort and lock_page_lruvec_irqsave are open coded to work with compact_control. Also add a debug func in locking which may give some clues if there are sth out of hands. Daniel Jordan's testing show 62% improvement on modified readtwice case on his 2P * 10 core * 2 HT broadwell box. https://lore.kernel.org/lkml/20200915165807.kpp7uhiw7l3loofu@ca-dmjordan1.us.oracle.com/ Hugh Dickins helped on the patch polish, thanks! [alex.shi@linux.alibaba.com: fix comment typo] Link: https://lkml.kernel.org/r/5b085715-292a-4b43-50b3-d73dc90d1de5@linux.alibaba.com [alex.shi@linux.alibaba.com: use page_memcg()] Link: https://lkml.kernel.org/r/5a4c2b72-7ee8-2478-fc0e-85eb83aafec4@linux.alibaba.com Link: https://lkml.kernel.org/r/1604566549-62481-18-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rong Chen <rong.a.chen@intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9df41314 |
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15-Dec-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/compaction: do page isolation first in compaction Currently, compaction would get the lru_lock and then do page isolation which works fine with pgdat->lru_lock, since any page isoltion would compete for the lru_lock. If we want to change to memcg lru_lock, we have to isolate the page before getting lru_lock, thus isoltion would block page's memcg change which relay on page isoltion too. Then we could safely use per memcg lru_lock later. The new page isolation use previous introduced TestClearPageLRU() + pgdat lru locking which will be changed to memcg lru lock later. Hugh Dickins <hughd@google.com> fixed following bugs in this patch's early version: Fix lots of crashes under compaction load: isolate_migratepages_block() must clean up appropriately when rejecting a page, setting PageLRU again if it had been cleared; and a put_page() after get_page_unless_zero() cannot safely be done while holding locked_lruvec - it may turn out to be the final put_page(), which will take an lruvec lock when PageLRU. And move __isolate_lru_page_prepare back after get_page_unless_zero to make trylock_page() safe: trylock_page() is not safe to use at this time: its setting PG_locked can race with the page being freed or allocated ("Bad page"), and can also erase flags being set by one of those "sole owners" of a freshly allocated page who use non-atomic __SetPageFlag(). Link: https://lkml.kernel.org/r/1604566549-62481-16-git-send-email-alex.shi@linux.alibaba.com Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d25b5bd8 |
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15-Dec-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/lru: introduce TestClearPageLRU() Currently lru_lock still guards both lru list and page's lru bit, that's ok. but if we want to use specific lruvec lock on the page, we need to pin down the page's lruvec/memcg during locking. Just taking lruvec lock first may be undermined by the page's memcg charge/migration. To fix this problem, we will clear the lru bit out of locking and use it as pin down action to block the page isolation in memcg changing. So now a standard steps of page isolation is following: 1, get_page(); #pin the page avoid to be free 2, TestClearPageLRU(); #block other isolation like memcg change 3, spin_lock on lru_lock; #serialize lru list access 4, delete page from lru list; This patch start with the first part: TestClearPageLRU, which combines PageLRU check and ClearPageLRU into a macro func TestClearPageLRU. This function will be used as page isolation precondition to prevent other isolations some where else. Then there are may !PageLRU page on lru list, need to remove BUG() checking accordingly. There 2 rules for lru bit now: 1, the lru bit still indicate if a page on lru list, just in some temporary moment(isolating), the page may have no lru bit when it's on lru list. but the page still must be on lru list when the lru bit set. 2, have to remove lru bit before delete it from lru list. As Andrew Morton mentioned this change would dirty cacheline for a page which isn't on the LRU. But the loss would be acceptable in Rong Chen <rong.a.chen@intel.com> report: https://lore.kernel.org/lkml/20200304090301.GB5972@shao2-debian/ Link: https://lkml.kernel.org/r/1604566549-62481-15-git-send-email-alex.shi@linux.alibaba.com Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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afca9157 |
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15-Dec-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/vmscan: remove lruvec reget in move_pages_to_lru Isolated page shouldn't be recharged by memcg since the memcg migration isn't possible at the time. All pages were isolated from the same lruvec (and isolation inhibits memcg migration). So remove unnecessary regetting. Thanks to Alexander Duyck for pointing this out. Link: https://lkml.kernel.org/r/1604566549-62481-12-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Michal Hocko <mhocko@kernel.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
75cc3c91 |
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15-Dec-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/lru: move lock into lru_note_cost We have to move lru_lock into lru_note_cost, since it cycle up on memcg tree, for future per lruvec lru_lock replace. It's a bit ugly and may cost a bit more locking, but benefit from multiple memcg locking could cover the lost. Link: https://lkml.kernel.org/r/1604566549-62481-11-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3d06afab |
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15-Dec-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/vmscan: remove unnecessary lruvec adding We don't have to add a freeable page into lru and then remove from it. This change saves a couple of actions and makes the moving more clear. The SetPageLRU needs to be kept before put_page_testzero for list integrity, otherwise: #0 move_pages_to_lru #1 release_pages if !put_page_testzero if (put_page_testzero()) !PageLRU //skip lru_lock SetPageLRU() list_add(&page->lru,) list_add(&page->lru,) [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/1604566549-62481-6-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
01359eb2 |
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14-Dec-2020 |
Gustavo A. R. Silva <gustavoars@kernel.org> |
mm: fix fall-through warnings for Clang In preparation to enable -Wimplicit-fallthrough for Clang, fix a couple of warnings by explicitly adding a break statement instead of just letting the code fall through to the next, and by adding a fallthrough pseudo-keyword in places where the code is intended to fall through. Link: https://github.com/KSPP/linux/issues/115 Link: https://lkml.kernel.org/r/f5756988b8842a3f10008fbc5b0a654f828920a9.1605896059.git.gustavoars@kernel.org Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d12b8951 |
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14-Dec-2020 |
Yang Shi <shy828301@gmail.com> |
mm: truncate_complete_page() does not exist any more Patch series "mm: misc migrate cleanup and improvement", v3. This patch (of 5): The commit 9f4e41f4717832e ("mm: refactor truncate_complete_page()") refactored truncate_complete_page(), and it is not existed anymore, correct the comment in vmscan and migrate to avoid confusion. Link: https://lkml.kernel.org/r/20201113205359.556831-1-shy828301@gmail.com Link: https://lkml.kernel.org/r/20201113205359.556831-2-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Song Liu <songliubraving@fb.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8d87d07c |
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14-Dec-2020 |
logic.yu <hymmsx.yu@gmail.com> |
mm/vmscan.c: remove the filename in the top of file comment No point in having the filename inside the file. Link: https://lkml.kernel.org/r/20201115141541.3878-1-hymmsx.yu@gmail.com Signed-off-by: logic.yu <hymmsx.yu@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2b47a24c |
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14-Dec-2020 |
Lukas Bulwahn <lukas.bulwahn@gmail.com> |
mm/vmscan: drop unneeded assignment in kswapd() The refactoring to kswapd() in commit e716f2eb24de ("mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx") turned an assignment to reclaim_order into a dead store, as in all further paths, reclaim_order will be assigned again before it is used. make clang-analyzer on x86_64 tinyconfig caught my attention with: mm/vmscan.c: warning: Although the value stored to 'reclaim_order' is used in the enclosing expression, the value is never actually read from 'reclaim_order' [clang-analyzer-deadcode.DeadStores] Compilers will detect this unneeded assignment and optimize this anyway. So, the resulting binary is identical before and after this change. Simplify the code and remove unneeded assignment to make clang-analyzer happy. No functional change. No change in binary code. Link: https://lkml.kernel.org/r/20201004125827.17679-1-lukas.bulwahn@gmail.com Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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013339df |
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14-Dec-2020 |
Shakeel Butt <shakeelb@google.com> |
mm/rmap: always do TTU_IGNORE_ACCESS Since commit 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic v2"), the code to check the secondary MMU's page table access bit is broken for !(TTU_IGNORE_ACCESS) because the page is unmapped from the secondary MMU's page table before the check. More specifically for those secondary MMUs which unmap the memory in mmu_notifier_invalidate_range_start() like kvm. However memory reclaim is the only user of !(TTU_IGNORE_ACCESS) or the absence of TTU_IGNORE_ACCESS and it explicitly performs the page table access check before trying to unmap the page. So, at worst the reclaim will miss accesses in a very short window if we remove page table access check in unmapping code. There is an unintented consequence of !(TTU_IGNORE_ACCESS) for the memcg reclaim. From memcg reclaim the page_referenced() only account the accesses from the processes which are in the same memcg of the target page but the unmapping code is considering accesses from all the processes, so, decreasing the effectiveness of memcg reclaim. The simplest solution is to always assume TTU_IGNORE_ACCESS in unmapping code. Link: https://lkml.kernel.org/r/20201104231928.1494083-1-shakeelb@google.com Fixes: 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic v2") Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2da9f630 |
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13-Nov-2020 |
Nicholas Piggin <npiggin@gmail.com> |
mm/vmscan: fix NR_ISOLATED_FILE corruption on 64-bit Previously the negated unsigned long would be cast back to signed long which would have the correct negative value. After commit 730ec8c01a2b ("mm/vmscan.c: change prototype for shrink_page_list"), the large unsigned int converts to a large positive signed long. Symptoms include CMA allocations hanging forever holding the cma_mutex due to alloc_contig_range->...->isolate_migratepages_block waiting forever in "while (unlikely(too_many_isolated(pgdat)))". [akpm@linux-foundation.org: fix -stat.nr_lazyfree_fail as well, per Michal] Fixes: 730ec8c01a2b ("mm/vmscan.c: change prototype for shrink_page_list") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vaneet Narang <v.narang@samsung.com> Cc: Maninder Singh <maninder1.s@samsung.com> Cc: Amit Sahrawat <a.sahrawat@samsung.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20201029032320.1448441-1-npiggin@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ed017373 |
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15-Oct-2020 |
Yu Zhao <yuzhao@google.com> |
mm: use self-explanatory macros rather than "2" Signed-off-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alex Shi <alex.shi@linux.alibaba.com> Link: http://lkml.kernel.org/r/20200831175042.3527153-2-yuzhao@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3efe62e4 |
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15-Oct-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/vmscan: allow arbitrary sized pages to be paged out Remove the assumption that a compound page has HPAGE_PMD_NR pins from the page cache. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: SeongJae Park <sjpark@amazon.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: "Huang, Ying" <ying.huang@intel.com> Link: https://lkml.kernel.org/r/20200908195539.25896-12-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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01c4776b |
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13-Oct-2020 |
Hui Su <sh_def@163.com> |
mm/vmscan: fix comments for isolate_lru_page() fix comments for isolate_lru_page(): s/fundamentnal/fundamental Signed-off-by: Hui Su <sh_def@163.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/20200927173923.GA8058@rlk Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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069c411d |
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13-Oct-2020 |
Chunxin Zang <zangchunxin@bytedance.com> |
mm/vmscan: fix infinite loop in drop_slab_node We have observed that drop_caches can take a considerable amount of time (<put data here>). Especially when there are many memcgs involved because they are adding an additional overhead. It is quite unfortunate that the operation cannot be interrupted by a signal currently. Add a check for fatal signals into the main loop so that userspace can control early bailout. There are two reasons: 1. We have too many memcgs, even though one object freed in one memcg, the sum of object is bigger than 10. 2. We spend a lot of time in traverse memcg once. So, the memcg who traversed at the first have been freed many objects. Traverse memcg next time, the freed count bigger than 10 again. We can get the following info through 'ps': root:~# ps -aux | grep drop root 357956 ... R Aug25 21119854:55 echo 3 > /proc/sys/vm/drop_caches root 1771385 ... R Aug16 21146421:17 echo 3 > /proc/sys/vm/drop_caches root 1986319 ... R 18:56 117:27 echo 3 > /proc/sys/vm/drop_caches root 2002148 ... R Aug24 5720:39 echo 3 > /proc/sys/vm/drop_caches root 2564666 ... R 18:59 113:58 echo 3 > /proc/sys/vm/drop_caches root 2639347 ... R Sep03 2383:39 echo 3 > /proc/sys/vm/drop_caches root 3904747 ... R 03:35 993:31 echo 3 > /proc/sys/vm/drop_caches root 4016780 ... R Aug21 7882:18 echo 3 > /proc/sys/vm/drop_caches Use bpftrace follow 'freed' value in drop_slab_node: root:~# bpftrace -e 'kprobe:drop_slab_node+70 {@ret=hist(reg("bp")); }' Attaching 1 probe... ^B^C @ret: [64, 128) 1 | | [128, 256) 28 | | [256, 512) 107 |@ | [512, 1K) 298 |@@@ | [1K, 2K) 613 |@@@@@@@ | [2K, 4K) 4435 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [4K, 8K) 442 |@@@@@ | [8K, 16K) 299 |@@@ | [16K, 32K) 100 |@ | [32K, 64K) 139 |@ | [64K, 128K) 56 | | [128K, 256K) 26 | | [256K, 512K) 2 | | In the while loop, we can check whether the TASK_KILLABLE signal is set, if so, we should break the loop. Signed-off-by: Chunxin Zang <zangchunxin@bytedance.com> Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Chris Down <chris@chrisdown.name> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Link: https://lkml.kernel.org/r/20200909152047.27905-1-zangchunxin@bytedance.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8d8869ca |
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18-Sep-2020 |
Hugh Dickins <hughd@google.com> |
mm: fix check_move_unevictable_pages() on THP check_move_unevictable_pages() is used in making unevictable shmem pages evictable: by shmem_unlock_mapping(), drm_gem_check_release_pagevec() and i915/gem check_release_pagevec(). Those may pass down subpages of a huge page, when /sys/kernel/mm/transparent_hugepage/shmem_enabled is "force". That does not crash or warn at present, but the accounting of vmstats unevictable_pgs_scanned and unevictable_pgs_rescued is inconsistent: scanned being incremented on each subpage, rescued only on the head (since tails already appear evictable once the head has been updated). 5.8 commit 5d91f31faf8e ("mm: swap: fix vmstats for huge page") has established that vm_events in general (and unevictable_pgs_rescued in particular) should count every subpage: so follow that precedent here. Do this in such a way that if mem_cgroup_page_lruvec() is made stricter (to check page->mem_cgroup is always set), no problem: skip the tails before calling it, and add thp_nr_pages() to vmstats on the head. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Yang Shi <shy828301@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Qian Cai <cai@lca.pw> Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301405000.5954@eggly.anvils Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e3336cab |
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04-Sep-2020 |
Xunlei Pang <xlpang@linux.alibaba.com> |
mm: memcg: fix memcg reclaim soft lockup We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg doesn't have any reclaimable memory. It can be easily reproduced as below: watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204] CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12 Call Trace: shrink_lruvec+0x49f/0x640 shrink_node+0x2a6/0x6f0 do_try_to_free_pages+0xe9/0x3e0 try_to_free_mem_cgroup_pages+0xef/0x1f0 try_charge+0x2c1/0x750 mem_cgroup_charge+0xd7/0x240 __add_to_page_cache_locked+0x2fd/0x370 add_to_page_cache_lru+0x4a/0xc0 pagecache_get_page+0x10b/0x2f0 filemap_fault+0x661/0xad0 ext4_filemap_fault+0x2c/0x40 __do_fault+0x4d/0xf9 handle_mm_fault+0x1080/0x1790 It only happens on our 1-vcpu instances, because there's no chance for oom reaper to run to reclaim the to-be-killed process. Add a cond_resched() at the upper shrink_node_memcgs() to solve this issue, this will mean that we will get a scheduling point for each memcg in the reclaimed hierarchy without any dependency on the reclaimable memory in that memcg thus making it more predictable. Suggested-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Chris Down <chris@chrisdown.name> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: http://lkml.kernel.org/r/1598495549-67324-1-git-send-email-xlpang@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6c357848 |
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14-Aug-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: replace hpage_nr_pages with thp_nr_pages The thp prefix is more frequently used than hpage and we should be consistent between the various functions. [akpm@linux-foundation.org: fix mm/migrate.c] Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/20200629151959.15779-6-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1eba09c1 |
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11-Aug-2020 |
Randy Dunlap <rdunlap@infradead.org> |
mm/vmscan.c: delete or fix duplicated words Drop the repeated word "marked". Change "time time" to "same time". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Link: http://lkml.kernel.org/r/20200801173822.14973-14-rdunlap@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4002570c |
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11-Aug-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/vmscan: restore active/inactive ratio for anonymous LRU Now that workingset detection is implemented for anonymous LRU, we don't need large inactive list to allow detecting frequently accessed pages before they are reclaimed, anymore. This effectively reverts the temporary measure put in by commit "mm/vmscan: make active/inactive ratio as 1:1 for anon lru". Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1595490560-15117-7-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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aae466b0 |
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11-Aug-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/swap: implement workingset detection for anonymous LRU This patch implements workingset detection for anonymous LRU. All the infrastructure is implemented by the previous patches so this patch just activates the workingset detection by installing/retrieving the shadow entry and adding refault calculation. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1595490560-15117-6-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3852f676 |
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11-Aug-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/swapcache: support to handle the shadow entries Workingset detection for anonymous page will be implemented in the following patch and it requires to store the shadow entries into the swapcache. This patch implements an infrastructure to store the shadow entry in the swapcache. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/1595490560-15117-5-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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170b04b7 |
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11-Aug-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/workingset: prepare the workingset detection infrastructure for anon LRU To prepare the workingset detection for anon LRU, this patch splits workingset event counters for refault, activate and restore into anon and file variants, as well as the refaults counter in struct lruvec. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1595490560-15117-4-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b518154e |
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11-Aug-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/vmscan: protect the workingset on anonymous LRU In current implementation, newly created or swap-in anonymous page is started on active list. Growing active list results in rebalancing active/inactive list so old pages on active list are demoted to inactive list. Hence, the page on active list isn't protected at all. Following is an example of this situation. Assume that 50 hot pages on active list. Numbers denote the number of pages on active/inactive list (active | inactive). 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(uo) | 50(h) 3. workload: another 50 newly created (used-once) pages 50(uo) | 50(uo), swap-out 50(h) This patch tries to fix this issue. Like as file LRU, newly created or swap-in anonymous pages will be inserted to the inactive list. They are promoted to active list if enough reference happens. This simple modification changes the above example as following. 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(h) | 50(uo) 3. workload: another 50 newly created (used-once) pages 50(h) | 50(uo), swap-out 50(uo) As you can see, hot pages on active list would be protected. Note that, this implementation has a drawback that the page cannot be promoted and will be swapped-out if re-access interval is greater than the size of inactive list but less than the size of total(active+inactive). To solve this potential issue, following patch will apply workingset detection similar to the one that's already applied to file LRU. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1595490560-15117-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ccc5dc67 |
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11-Aug-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/vmscan: make active/inactive ratio as 1:1 for anon lru Patch series "workingset protection/detection on the anonymous LRU list", v7. * PROBLEM In current implementation, newly created or swap-in anonymous page is started on the active list. Growing the active list results in rebalancing active/inactive list so old pages on the active list are demoted to the inactive list. Hence, hot page on the active list isn't protected at all. Following is an example of this situation. Assume that 50 hot pages on active list and system can contain total 100 pages. Numbers denote the number of pages on active/inactive list (active | inactive). (h) stands for hot pages and (uo) stands for used-once pages. 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(uo) | 50(h) 3. workload: another 50 newly created (used-once) pages 50(uo) | 50(uo), swap-out 50(h) As we can see, hot pages are swapped-out and it would cause swap-in later. * SOLUTION Since this is what we want to avoid, this patchset implements workingset protection. Like as the file LRU list, newly created or swap-in anonymous page is started on the inactive list. Also, like as the file LRU list, if enough reference happens, the page will be promoted. This simple modification changes the above example as following. 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(h) | 50(uo) 3. workload: another 50 newly created (used-once) pages 50(h) | 50(uo), swap-out 50(uo) hot pages remains in the active list. :) * EXPERIMENT I tested this scenario on my test bed and confirmed that this problem happens on current implementation. I also checked that it is fixed by this patchset. * SUBJECT workingset detection * PROBLEM Later part of the patchset implements the workingset detection for the anonymous LRU list. There is a corner case that workingset protection could cause thrashing. If we can avoid thrashing by workingset detection, we can get the better performance. Following is an example of thrashing due to the workingset protection. 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (will be hot) pages 50(h) | 50(wh) 3. workload: another 50 newly created (used-once) pages 50(h) | 50(uo), swap-out 50(wh) 4. workload: 50 (will be hot) pages 50(h) | 50(wh), swap-in 50(wh) 5. workload: another 50 newly created (used-once) pages 50(h) | 50(uo), swap-out 50(wh) 6. repeat 4, 5 Without workingset detection, this kind of workload cannot be promoted and thrashing happens forever. * SOLUTION Therefore, this patchset implements workingset detection. All the infrastructure for workingset detecion is already implemented, so there is not much work to do. First, extend workingset detection code to deal with the anonymous LRU list. Then, make swap cache handles the exceptional value for the shadow entry. Lastly, install/retrieve the shadow value into/from the swap cache and check the refault distance. * EXPERIMENT I made a test program to imitates above scenario and confirmed that problem exists. Then, I checked that this patchset fixes it. My test setup is a virtual machine with 8 cpus and 6100MB memory. But, the amount of the memory that the test program can use is about 280 MB. This is because the system uses large ram-backed swap and large ramdisk to capture the trace. Test scenario is like as below. 1. allocate cold memory (512MB) 2. allocate hot-1 memory (96MB) 3. activate hot-1 memory (96MB) 4. allocate another hot-2 memory (96MB) 5. access cold memory (128MB) 6. access hot-2 memory (96MB) 7. repeat 5, 6 Since hot-1 memory (96MB) is on the active list, the inactive list can contains roughly 190MB pages. hot-2 memory's re-access interval (96+128 MB) is more 190MB, so it cannot be promoted without workingset detection and swap-in/out happens repeatedly. With this patchset, workingset detection works and promotion happens. Therefore, swap-in/out occurs less. Here is the result. (average of 5 runs) type swap-in swap-out base 863240 989945 patch 681565 809273 As we can see, patched kernel do less swap-in/out. * OVERALL TEST (ebizzy using modified random function) ebizzy is the test program that main thread allocates lots of memory and child threads access them randomly during the given times. Swap-in will happen if allocated memory is larger than the system memory. The random function that represents the zipf distribution is used to make hot/cold memory. Hot/cold ratio is controlled by the parameter. If the parameter is high, hot memory is accessed much larger than cold one. If the parameter is low, the number of access on each memory would be similar. I uses various parameters in order to show the effect of patchset on various hot/cold ratio workload. My test setup is a virtual machine with 8 cpus, 1024 MB memory and 5120 MB ram swap. Result format is as following. param: 1-1024-0.1 - 1 (number of thread) - 1024 (allocated memory size, MB) - 0.1 (zipf distribution alpha, 0.1 works like as roughly uniform random, 1.3 works like as small portion of memory is hot and the others are cold) pswpin: smaller is better std: standard deviation improvement: negative is better * single thread param pswpin std improvement base 1-1024.0-0.1 14101983.40 79441.19 prot 1-1024.0-0.1 14065875.80 136413.01 ( -0.26 ) detect 1-1024.0-0.1 13910435.60 100804.82 ( -1.36 ) base 1-1024.0-0.7 7998368.80 43469.32 prot 1-1024.0-0.7 7622245.80 88318.74 ( -4.70 ) detect 1-1024.0-0.7 7618515.20 59742.07 ( -4.75 ) base 1-1024.0-1.3 1017400.80 38756.30 prot 1-1024.0-1.3 940464.60 29310.69 ( -7.56 ) detect 1-1024.0-1.3 945511.40 24579.52 ( -7.07 ) base 1-1280.0-0.1 22895541.40 50016.08 prot 1-1280.0-0.1 22860305.40 51952.37 ( -0.15 ) detect 1-1280.0-0.1 22705565.20 93380.35 ( -0.83 ) base 1-1280.0-0.7 13717645.60 46250.65 prot 1-1280.0-0.7 12935355.80 64754.43 ( -5.70 ) detect 1-1280.0-0.7 13040232.00 63304.00 ( -4.94 ) base 1-1280.0-1.3 1654251.40 4159.68 prot 1-1280.0-1.3 1522680.60 33673.50 ( -7.95 ) detect 1-1280.0-1.3 1599207.00 70327.89 ( -3.33 ) base 1-1536.0-0.1 31621775.40 31156.28 prot 1-1536.0-0.1 31540355.20 62241.36 ( -0.26 ) detect 1-1536.0-0.1 31420056.00 123831.27 ( -0.64 ) base 1-1536.0-0.7 19620760.60 60937.60 prot 1-1536.0-0.7 18337839.60 56102.58 ( -6.54 ) detect 1-1536.0-0.7 18599128.00 75289.48 ( -5.21 ) base 1-1536.0-1.3 2378142.40 20994.43 prot 1-1536.0-1.3 2166260.60 48455.46 ( -8.91 ) detect 1-1536.0-1.3 2183762.20 16883.24 ( -8.17 ) base 1-1792.0-0.1 40259714.80 90750.70 prot 1-1792.0-0.1 40053917.20 64509.47 ( -0.51 ) detect 1-1792.0-0.1 39949736.40 104989.64 ( -0.77 ) base 1-1792.0-0.7 25704884.40 69429.68 prot 1-1792.0-0.7 23937389.00 79945.60 ( -6.88 ) detect 1-1792.0-0.7 24271902.00 35044.30 ( -5.57 ) base 1-1792.0-1.3 3129497.00 32731.86 prot 1-1792.0-1.3 2796994.40 19017.26 ( -10.62 ) detect 1-1792.0-1.3 2886840.40 33938.82 ( -7.75 ) base 1-2048.0-0.1 48746924.40 50863.88 prot 1-2048.0-0.1 48631954.40 24537.30 ( -0.24 ) detect 1-2048.0-0.1 48509419.80 27085.34 ( -0.49 ) base 1-2048.0-0.7 32046424.40 78624.22 prot 1-2048.0-0.7 29764182.20 86002.26 ( -7.12 ) detect 1-2048.0-0.7 30250315.80 101282.14 ( -5.60 ) base 1-2048.0-1.3 3916723.60 24048.55 prot 1-2048.0-1.3 3490781.60 33292.61 ( -10.87 ) detect 1-2048.0-1.3 3585002.20 44942.04 ( -8.47 ) * multi thread param pswpin std improvement base 8-1024.0-0.1 16219822.60 329474.01 prot 8-1024.0-0.1 15959494.00 654597.45 ( -1.61 ) detect 8-1024.0-0.1 15773790.80 502275.25 ( -2.75 ) base 8-1024.0-0.7 9174107.80 537619.33 prot 8-1024.0-0.7 8571915.00 385230.08 ( -6.56 ) detect 8-1024.0-0.7 8489484.20 364683.00 ( -7.46 ) base 8-1024.0-1.3 1108495.60 83555.98 prot 8-1024.0-1.3 1038906.20 63465.20 ( -6.28 ) detect 8-1024.0-1.3 941817.80 32648.80 ( -15.04 ) base 8-1280.0-0.1 25776114.20 450480.45 prot 8-1280.0-0.1 25430847.00 465627.07 ( -1.34 ) detect 8-1280.0-0.1 25282555.00 465666.55 ( -1.91 ) base 8-1280.0-0.7 15218968.00 702007.69 prot 8-1280.0-0.7 13957947.80 492643.86 ( -8.29 ) detect 8-1280.0-0.7 14158331.20 238656.02 ( -6.97 ) base 8-1280.0-1.3 1792482.80 30512.90 prot 8-1280.0-1.3 1577686.40 34002.62 ( -11.98 ) detect 8-1280.0-1.3 1556133.00 22944.79 ( -13.19 ) base 8-1536.0-0.1 33923761.40 575455.85 prot 8-1536.0-0.1 32715766.20 300633.51 ( -3.56 ) detect 8-1536.0-0.1 33158477.40 117764.51 ( -2.26 ) base 8-1536.0-0.7 20628907.80 303851.34 prot 8-1536.0-0.7 19329511.20 341719.31 ( -6.30 ) detect 8-1536.0-0.7 20013934.00 385358.66 ( -2.98 ) base 8-1536.0-1.3 2588106.40 130769.20 prot 8-1536.0-1.3 2275222.40 89637.06 ( -12.09 ) detect 8-1536.0-1.3 2365008.40 124412.55 ( -8.62 ) base 8-1792.0-0.1 43328279.20 946469.12 prot 8-1792.0-0.1 41481980.80 525690.89 ( -4.26 ) detect 8-1792.0-0.1 41713944.60 406798.93 ( -3.73 ) base 8-1792.0-0.7 27155647.40 536253.57 prot 8-1792.0-0.7 24989406.80 502734.52 ( -7.98 ) detect 8-1792.0-0.7 25524806.40 263237.87 ( -6.01 ) base 8-1792.0-1.3 3260372.80 137907.92 prot 8-1792.0-1.3 2879187.80 63597.26 ( -11.69 ) detect 8-1792.0-1.3 2892962.20 33229.13 ( -11.27 ) base 8-2048.0-0.1 50583989.80 710121.48 prot 8-2048.0-0.1 49599984.40 228782.42 ( -1.95 ) detect 8-2048.0-0.1 50578596.00 660971.66 ( -0.01 ) base 8-2048.0-0.7 33765479.60 812659.55 prot 8-2048.0-0.7 30767021.20 462907.24 ( -8.88 ) detect 8-2048.0-0.7 32213068.80 211884.24 ( -4.60 ) base 8-2048.0-1.3 3941675.80 28436.45 prot 8-2048.0-1.3 3538742.40 76856.08 ( -10.22 ) detect 8-2048.0-1.3 3579397.80 58630.95 ( -9.19 ) As we can see, all the cases show improvement. Especially, test case with zipf distribution 1.3 show more improvements. It means that if there is a hot/cold tendency in anon pages, this patchset works better. This patch (of 6): Current implementation of LRU management for anonymous page has some problems. Most important one is that it doesn't protect the workingset, that is, pages on the active LRU list. Although, this problem will be fixed in the following patchset, the preparation is required and this patch does it. What following patch does is to implement workingset protection. After the following patchset, newly created or swap-in pages will start their lifetime on the inactive list. If inactive list is too small, there is not enough chance to be referenced and the page cannot become the workingset. In order to provide the newly anonymous or swap-in pages enough chance to be referenced again, this patch makes active/inactive LRU ratio as 1:1. This is just a temporary measure. Later patch in the series introduces workingset detection for anonymous LRU that will be used to better decide if pages should start on the active and inactive list. Afterwards this patch is effectively reverted. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Matthew Wilcox <willy@infradead.org> Link: http://lkml.kernel.org/r/1595490560-15117-1-git-send-email-iamjoonsoo.kim@lge.com Link: http://lkml.kernel.org/r/1595490560-15117-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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912c0572 |
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07-Aug-2020 |
Shakeel Butt <shakeelb@google.com> |
mm: vmscan: consistent update to pgrefill The vmstat pgrefill is useful together with pgscan and pgsteal stats to measure the reclaim efficiency. However vmstat's pgrefill is not updated consistently at system level. It gets updated for both global and memcg reclaim however pgscan and pgsteal are updated for only global reclaim. So, update pgrefill only for global reclaim. If someone is interested in the stats representing both system level as well as memcg level reclaim, then consult the root memcg's memory.stat instead of /proc/vmstat. Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Yafang Shao <laoar.shao@gmail.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Chris Down <chris@chrisdown.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Link: http://lkml.kernel.org/r/20200711011459.1159929-1-shakeelb@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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238c3046 |
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07-Aug-2020 |
dylan-meiners <spacct.spacct@gmail.com> |
mm/vmscan.c: fix typo Change "optizimation" to "optimization". Signed-off-by: dylan-meiners <spacct.spacct@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Link: http://lkml.kernel.org/r/20200609185144.10049-1-spacct.spacct@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0a18e607 |
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07-Aug-2020 |
David Hildenbrand <david@redhat.com> |
mm: remove vm_total_pages The global variable "vm_total_pages" is a relic from older days. There is only a single user that reads the variable - build_all_zonelists() - and the first thing it does is update it. Use a local variable in build_all_zonelists() instead and remove the global variable. Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/20200619132410.23859-2-david@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e22c6ed9 |
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07-Aug-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: don't count limit-setting reclaim as memory pressure When an outside process lowers one of the memory limits of a cgroup (or uses the force_empty knob in cgroup1), direct reclaim is performed in the context of the write(), in order to directly enforce the new limit and have it being met by the time the write() returns. Currently, this reclaim activity is accounted as memory pressure in the cgroup that the writer(!) belongs to. This is unexpected. It specifically causes problems for senpai (https://github.com/facebookincubator/senpai), which is an agent that routinely adjusts the memory limits and performs associated reclaim work in tens or even hundreds of cgroups running on the host. The cgroup that senpai is running in itself will report elevated levels of memory pressure, even though it itself is under no memory shortage or any sort of distress. Move the psi annotation from the central cgroup reclaim function to callsites in the allocation context, and thereby no longer count any limit-setting reclaim as memory pressure. If the newly set limit causes the workload inside the cgroup into direct reclaim, that of course will continue to count as memory pressure. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Roman Gushchin <guro@fb.com> Acked-by: Chris Down <chris@chrisdown.name> Acked-by: Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200728135210.379885-2-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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45c7f7e1 |
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07-Aug-2020 |
Chris Down <chris@chrisdown.name> |
mm, memcg: decouple e{low,min} state mutations from protection checks mem_cgroup_protected currently is both used to set effective low and min and return a mem_cgroup_protection based on the result. As a user, this can be a little unexpected: it appears to be a simple predicate function, if not for the big warning in the comment above about the order in which it must be executed. This change makes it so that we separate the state mutations from the actual protection checks, which makes it more obvious where we need to be careful mutating internal state, and where we are simply checking and don't need to worry about that. [mhocko@suse.com - don't check protection on root memcgs] Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <guro@fb.com> Cc: Yafang Shao <laoar.shao@gmail.com> Link: http://lkml.kernel.org/r/ff3f915097fcee9f6d7041c084ef92d16aaeb56a.1594638158.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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22f7496f |
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07-Aug-2020 |
Yafang Shao <laoar.shao@gmail.com> |
mm, memcg: avoid stale protection values when cgroup is above protection Patch series "mm, memcg: memory.{low,min} reclaim fix & cleanup", v4. This series contains a fix for a edge case in my earlier protection calculation patches, and a patch to make the area overall a little more robust to hopefully help avoid this in future. This patch (of 2): A cgroup can have both memory protection and a memory limit to isolate it from its siblings in both directions - for example, to prevent it from being shrunk below 2G under high pressure from outside, but also from growing beyond 4G under low pressure. Commit 9783aa9917f8 ("mm, memcg: proportional memory.{low,min} reclaim") implemented proportional scan pressure so that multiple siblings in excess of their protection settings don't get reclaimed equally but instead in accordance to their unprotected portion. During limit reclaim, this proportionality shouldn't apply of course: there is no competition, all pressure is from within the cgroup and should be applied as such. Reclaim should operate at full efficiency. However, mem_cgroup_protected() never expected anybody to look at the effective protection values when it indicated that the cgroup is above its protection. As a result, a query during limit reclaim may return stale protection values that were calculated by a previous reclaim cycle in which the cgroup did have siblings. When this happens, reclaim is unnecessarily hesitant and potentially slow to meet the desired limit. In theory this could lead to premature OOM kills, although it's not obvious this has occurred in practice. Workaround the problem by special casing reclaim roots in mem_cgroup_protection. These memcgs are never participating in the reclaim protection because the reclaim is internal. We have to ignore effective protection values for reclaim roots because mem_cgroup_protected might be called from racing reclaim contexts with different roots. Calculation is relying on root -> leaf tree traversal therefore top-down reclaim protection invariants should hold. The only exception is the reclaim root which should have effective protection set to 0 but that would be problematic for the following setup: Let's have global and A's reclaim in parallel: | A (low=2G, usage = 3G, max = 3G, children_low_usage = 1.5G) |\ | C (low = 1G, usage = 2.5G) B (low = 1G, usage = 0.5G) for A reclaim we have B.elow = B.low C.elow = C.low For the global reclaim A.elow = A.low B.elow = min(B.usage, B.low) because children_low_usage <= A.elow C.elow = min(C.usage, C.low) With the effective values resetting we have A reclaim A.elow = 0 B.elow = B.low C.elow = C.low and global reclaim could see the above and then B.elow = C.elow = 0 because children_low_usage > A.elow Which means that protected memcgs would get reclaimed. In future we would like to make mem_cgroup_protected more robust against racing reclaim contexts but that is likely more complex solution than this simple workaround. [hannes@cmpxchg.org - large part of the changelog] [mhocko@suse.com - workaround explanation] [chris@chrisdown.name - retitle] Fixes: 9783aa9917f8 ("mm, memcg: proportional memory.{low,min} reclaim") Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Chris Down <chris@chrisdown.name> Acked-by: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/cover.1594638158.git.chris@chrisdown.name Link: http://lkml.kernel.org/r/044fb8ecffd001c7905d27c0c2ad998069fdc396.1594638158.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d42f3245 |
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07-Aug-2020 |
Roman Gushchin <guro@fb.com> |
mm: memcg: convert vmstat slab counters to bytes In order to prepare for per-object slab memory accounting, convert NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE vmstat items to bytes. To make it obvious, rename them to NR_SLAB_RECLAIMABLE_B and NR_SLAB_UNRECLAIMABLE_B (similar to NR_KERNEL_STACK_KB). Internally global and per-node counters are stored in pages, however memcg and lruvec counters are stored in bytes. This scheme may look weird, but only for now. As soon as slab pages will be shared between multiple cgroups, global and node counters will reflect the total number of slab pages. However memcg and lruvec counters will be used for per-memcg slab memory tracking, which will take separate kernel objects in the account. Keeping global and node counters in pages helps to avoid additional overhead. The size of slab memory shouldn't exceed 4Gb on 32-bit machines, so it will fit into atomic_long_t we use for vmstats. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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31d8fcac |
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25-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: workingset: age nonresident information alongside anonymous pages Patch series "fix for "mm: balance LRU lists based on relative thrashing" patchset" This patchset fixes some problems of the patchset, "mm: balance LRU lists based on relative thrashing", which is now merged on the mainline. Patch "mm: workingset: let cache workingset challenge anon fix" is the result of discussion with Johannes. See following link. http://lkml.kernel.org/r/20200520232525.798933-6-hannes@cmpxchg.org And, the other two are minor things which are found when I try to rebase my patchset. This patch (of 3): After ("mm: workingset: let cache workingset challenge anon fix"), we compare refault distances to active_file + anon. But age of the non-resident information is only driven by the file LRU. As a result, we may overestimate the recency of any incoming refaults and activate them too eagerly, causing unnecessary LRU churn in certain situations. Make anon aging drive nonresident age as well to address that. Link: http://lkml.kernel.org/r/1592288204-27734-1-git-send-email-iamjoonsoo.kim@lge.com Link: http://lkml.kernel.org/r/1592288204-27734-2-git-send-email-iamjoonsoo.kim@lge.com Fixes: 34e58cac6d8f2a ("mm: workingset: let cache workingset challenge anon") Reported-by: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Rik van Riel <riel@surriel.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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55b65a57 |
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04-Jun-2020 |
Ethon Paul <ethp@qq.com> |
mm/vmsan: fix some typos in comment There are some typos, fix them. s/regsitration/registration s/santity/sanity s/decremeting/decrementing Signed-off-by: Ethon Paul <ethp@qq.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Link: http://lkml.kernel.org/r/20200411071544.16222-1-ethp@qq.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d483a5dd |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: limit the range of LRU type balancing When LRU cost only shows up on one list, we abruptly stop scanning that list altogether. That's an extreme reaction: by the time the other list starts thrashing and the pendulum swings back, we may have no recent age information on the first list anymore, and we could have significant latencies until the scanner has caught up. Soften this change in the feedback system by ensuring that no list receives less than a third of overall pressure, and only distribute the other 66% according to LRU cost. This ensures that we maintain a minimum rate of aging on the entire workingset while it's being pressured, while still allowing a generous rate of convergence when the relative sizes of the lists need to adjust. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-15-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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96f8bf4f |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: reclaim writepage is IO cost The VM tries to balance reclaim pressure between anon and file so as to reduce the amount of IO incurred due to the memory shortage. It already counts refaults and swapins, but in addition it should also count writepage calls during reclaim. For swap, this is obvious: it's IO that wouldn't have occurred if the anonymous memory hadn't been under memory pressure. From a relative balancing point of view this makes sense as well: even if anon is cold and reclaimable, a cache that isn't thrashing may have equally cold pages that don't require IO to reclaim. For file writeback, it's trickier: some of the reclaim writepage IO would have likely occurred anyway due to dirty expiration. But not all of it - premature writeback reduces batching and generates additional writes. Since the flushers are already woken up by the time the VM starts writing cache pages one by one, let's assume that we'e likely causing writes that wouldn't have happened without memory pressure. In addition, the per-page cost of IO would have probably been much cheaper if written in larger batches from the flusher thread rather than the single-page-writes from kswapd. For our purposes - getting the trend right to accelerate convergence on a stable state that doesn't require paging at all - this is sufficiently accurate. If we later wanted to optimize for sustained thrashing, we can still refine the measurements. Count all writepage calls from kswapd as IO cost toward the LRU that the page belongs to. Why do this dynamically? Don't we know in advance that anon pages require IO to reclaim, and so could build in a static bias? First, scanning is not the same as reclaiming. If all the anon pages are referenced, we may not swap for a while just because we're scanning the anon list. During this time, however, it's important that we age anonymous memory and the page cache at the same rate so that their hot-cold gradients are comparable. Everything else being equal, we still want to reclaim the coldest memory overall. Second, we keep copies in swap unless the page changes. If there is swap-backed data that's mostly read (tmpfs file) and has been swapped out before, we can reclaim it without incurring additional IO. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-14-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7cf111bc |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: determine anon/file pressure balance at the reclaim root We split the LRU lists into anon and file, and we rebalance the scan pressure between them when one of them begins thrashing: if the file cache experiences workingset refaults, we increase the pressure on anonymous pages; if the workload is stalled on swapins, we increase the pressure on the file cache instead. With cgroups and their nested LRU lists, we currently don't do this correctly. While recursive cgroup reclaim establishes a relative LRU order among the pages of all involved cgroups, LRU pressure balancing is done on an individual cgroup LRU level. As a result, when one cgroup is thrashing on the filesystem cache while a sibling may have cold anonymous pages, pressure doesn't get equalized between them. This patch moves LRU balancing decision to the root of reclaim - the same level where the LRU order is established. It does this by tracking LRU cost recursively, so that every level of the cgroup tree knows the aggregate LRU cost of all memory within its domain. When the page scanner calculates the scan balance for any given individual cgroup's LRU list, it uses the values from the ancestor cgroup that initiated the reclaim cycle. If one sibling is then thrashing on the cache, it will tip the pressure balance inside its ancestors, and the next hierarchical reclaim iteration will go more after the anon pages in the tree. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-13-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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314b57fb |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: balance LRU lists based on relative thrashing Since the LRUs were split into anon and file lists, the VM has been balancing between page cache and anonymous pages based on per-list ratios of scanned vs. rotated pages. In most cases that tips page reclaim towards the list that is easier to reclaim and has the fewest actively used pages, but there are a few problems with it: 1. Refaults and LRU rotations are weighted the same way, even though one costs IO and the other costs a bit of CPU. 2. The less we scan an LRU list based on already observed rotations, the more we increase the sampling interval for new references, and rotations become even more likely on that list. This can enter a death spiral in which we stop looking at one list completely until the other one is all but annihilated by page reclaim. Since commit a528910e12ec ("mm: thrash detection-based file cache sizing") we have refault detection for the page cache. Along with swapin events, they are good indicators of when the file or anon list, respectively, is too small for its workingset and needs to grow. For example, if the page cache is thrashing, the cache pages need more time in memory, while there may be colder pages on the anonymous list. Likewise, if swapped pages are faulting back in, it indicates that we reclaim anonymous pages too aggressively and should back off. Replace LRU rotations with refaults and swapins as the basis for relative reclaim cost of the two LRUs. This will have the VM target list balances that incur the least amount of IO on aggregate. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-12-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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264e90cc |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: only count actual rotations as LRU reclaim cost When shrinking the active file list we rotate referenced pages only when they're in an executable mapping. The others get deactivated. When it comes to balancing scan pressure, though, we count all referenced pages as rotated, even the deactivated ones. Yet they do not carry the same cost to the system: the deactivated page *might* refault later on, but the deactivation is tangible progress toward freeing pages; rotations on the other hand cost time and effort without getting any closer to freeing memory. Don't treat both events as equal. The following patch will hook up LRU balancing to cache and anon refaults, which are a much more concrete cost signal for reclaiming one list over the other. Thus, remove the maybe-IO cost bias from page references, and only note the CPU cost for actual rotations that prevent the pages from getting reclaimed. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-11-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1431d4d1 |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: base LRU balancing on an explicit cost model Currently, scan pressure between the anon and file LRU lists is balanced based on a mixture of reclaim efficiency and a somewhat vague notion of "value" of having certain pages in memory over others. That concept of value is problematic, because it has caused us to count any event that remotely makes one LRU list more or less preferrable for reclaim, even when these events are not directly comparable and impose very different costs on the system. One example is referenced file pages that we still deactivate and referenced anonymous pages that we actually rotate back to the head of the list. There is also conceptual overlap with the LRU algorithm itself. By rotating recently used pages instead of reclaiming them, the algorithm already biases the applied scan pressure based on page value. Thus, when rebalancing scan pressure due to rotations, we should think of reclaim cost, and leave assessing the page value to the LRU algorithm. Lastly, considering both value-increasing as well as value-decreasing events can sometimes cause the same type of event to be counted twice, i.e. how rotating a page increases the LRU value, while reclaiming it succesfully decreases the value. In itself this will balance out fine, but it quietly skews the impact of events that are only recorded once. The abstract metric of "value", the murky relationship with the LRU algorithm, and accounting both negative and positive events make the current pressure balancing model hard to reason about and modify. This patch switches to a balancing model of accounting the concrete, actually observed cost of reclaiming one LRU over another. For now, that cost includes pages that are scanned but rotated back to the list head. Subsequent patches will add consideration for IO caused by refaulting of recently evicted pages. Replace struct zone_reclaim_stat with two cost counters in the lruvec, and make everything that affects cost go through a new lru_note_cost() function. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-9-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a4fe1631 |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: drop unnecessary div0 avoidance rounding in get_scan_count() When we calculate the relative scan pressure between the anon and file LRU lists, we have to assume that reclaim_stat can contain zeroes. To avoid div0 crashes, we add 1 to all denominators like so: anon_prio = swappiness; file_prio = 200 - anon_prio; [...] /* * The amount of pressure on anon vs file pages is inversely * proportional to the fraction of recently scanned pages on * each list that were recently referenced and in active use. */ ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); ap /= reclaim_stat->recent_rotated[0] + 1; fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; spin_unlock_irq(&pgdat->lru_lock); fraction[0] = ap; fraction[1] = fp; denominator = ap + fp + 1; While reclaim_stat can contain 0, it's not actually possible for ap + fp to be 0. One of anon_prio or file_prio could be zero, but they must still add up to 200. And the reclaim_stat fraction, due to the +1 in there, is always at least 1. So if one of the two numerators is 0, the other one can't be. ap + fp is always at least 1. Drop the + 1. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-8-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c843966c |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: allow swappiness that prefers reclaiming anon over the file workingset With the advent of fast random IO devices (SSDs, PMEM) and in-memory swap devices such as zswap, it's possible for swap to be much faster than filesystems, and for swapping to be preferable over thrashing filesystem caches. Allow setting swappiness - which defines the rough relative IO cost of cache misses between page cache and swap-backed pages - to reflect such situations by making the swap-preferred range configurable. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-4-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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497a6c1b |
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03-Jun-2020 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: keep separate anon and file statistics on page reclaim activity Having statistics on pages scanned and pages reclaimed for both anon and file pages makes it easier to evaluate changes to LRU balancing. While at it, clean up the stat-keeping mess for isolation, putback, reclaim stats etc. a bit: first the physical LRU operation (isolation and putback), followed by vmstats, reclaim_stats, and then vm events. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-3-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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df3a45f9 |
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03-Jun-2020 |
Qiwu Chen <qiwuchen55@gmail.com> |
mm/vmscan: update the comment of should_continue_reclaim() try_to_compact_zone() has been replaced by try_to_compact_pages(), which is necessary to be updated in the comment of should_continue_reclaim(). Signed-off-by: Qiwu Chen <chenqiwu@xiaomi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200501034907.22991-1-chenqiwu@xiaomi.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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730ec8c0 |
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03-Jun-2020 |
Maninder Singh <maninder1.s@samsung.com> |
mm/vmscan.c: change prototype for shrink_page_list commit 3c710c1ad11b ("mm, vmscan extract shrink_page_list reclaim counters into a struct") changed data type for the function, so changing return type for funciton and its caller. Signed-off-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Amit Sahrawat <a.sahrawat@samsung.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/1588168259-25604-1-git-send-email-maninder1.s@samsung.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1f318a9b |
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03-Jun-2020 |
Jaewon Kim <jaewon31.kim@samsung.com> |
mm/vmscan: count layzfree pages and fix nr_isolated_* mismatch Fix an nr_isolate_* mismatch problem between cma and dirty lazyfree pages. If try_to_unmap_one is used for reclaim and it detects a dirty lazyfree page, then the lazyfree page is changed to a normal anon page having SwapBacked by commit 802a3a92ad7a ("mm: reclaim MADV_FREE pages"). Even with the change, reclaim context correctly counts isolated files because it uses is_file_lru to distinguish file. And the change to anon is not happened if try_to_unmap_one is used for migration. So migration context like compaction also correctly counts isolated files even though it uses page_is_file_lru insted of is_file_lru. Recently page_is_file_cache was renamed to page_is_file_lru by commit 9de4f22a60f7 ("mm: code cleanup for MADV_FREE"). But the nr_isolate_* mismatch problem happens on cma alloc. There is reclaim_clean_pages_from_list which is being used only by cma. It was introduced by commit 02c6de8d757c ("mm: cma: discard clean pages during contiguous allocation instead of migration") to reclaim clean file pages without migration. The cma alloc uses both reclaim_clean_pages_from_list and migrate_pages, and it uses page_is_file_lru to count isolated files. If there are dirty lazyfree pages allocated from cma memory region, the pages are counted as isolated file at the beginging but are counted as isolated anon after finished. Mem-Info: Node 0 active_anon:3045904kB inactive_anon:611448kB active_file:14892kB inactive_file:205636kB unevictable:10416kB isolated(anon):0kB isolated(file):37664kB mapped:630216kB dirty:384kB writeback:0kB shmem:42576kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no Like log above, there were too much isolated files, 37664kB, which triggers too_many_isolated in reclaim even when there is no actually isolated file in system wide. It could be reproducible by running two programs, writing on MADV_FREE page and doing cma alloc, respectively. Although isolated anon is 0, I found that the internal value of isolated anon was the negative value of isolated file. Fix this by compensating the isolated count for both LRU lists. Count non-discarded lazyfree pages in shrink_page_list, then compensate the counted number in reclaim_clean_pages_from_list. Reported-by: Yong-Taek Lee <ytk.lee@samsung.com> Suggested-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Shaohua Li <shli@fb.com> Link: http://lkml.kernel.org/r/20200426011718.30246-1-jaewon31.kim@samsung.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a892cb6b |
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03-Jun-2020 |
Wei Yang <richard.weiyang@gmail.com> |
mm/vmscan.c: use update_lru_size() in update_lru_sizes() We already defined the helper update_lru_size(). Let's use this to reduce code duplication. Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Baoquan He <bhe@redhat.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200331221550.1011-1-richard.weiyang@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ff45fc3c |
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03-Jun-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: simplify calling a compound page destructor None of the three callers of get_compound_page_dtor() want to know the value; they just want to call the function. Replace it with destroy_compound_page() which calls the dtor for them. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/20200517105051.9352-1-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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97a225e6 |
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03-Jun-2020 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/page_alloc: integrate classzone_idx and high_zoneidx classzone_idx is just different name for high_zoneidx now. So, integrate them and add some comment to struct alloc_context in order to reduce future confusion about the meaning of this variable. The accessor, ac_classzone_idx() is also removed since it isn't needed after integration. In addition to integration, this patch also renames high_zoneidx to highest_zoneidx since it represents more precise meaning. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Baoquan He <bhe@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Ye Xiaolong <xiaolong.ye@intel.com> Link: http://lkml.kernel.org/r/1587095923-7515-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a37b0715 |
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01-Jun-2020 |
NeilBrown <neilb@suse.de> |
mm/writeback: replace PF_LESS_THROTTLE with PF_LOCAL_THROTTLE PF_LESS_THROTTLE exists for loop-back nfsd (and a similar need in the loop block driver and callers of prctl(PR_SET_IO_FLUSHER)), where a daemon needs to write to one bdi (the final bdi) in order to free up writes queued to another bdi (the client bdi). The daemon sets PF_LESS_THROTTLE and gets a larger allowance of dirty pages, so that it can still dirty pages after other processses have been throttled. The purpose of this is to avoid deadlock that happen when the PF_LESS_THROTTLE process must write for any dirty pages to be freed, but it is being thottled and cannot write. This approach was designed when all threads were blocked equally, independently on which device they were writing to, or how fast it was. Since that time the writeback algorithm has changed substantially with different threads getting different allowances based on non-trivial heuristics. This means the simple "add 25%" heuristic is no longer reliable. The important issue is not that the daemon needs a *larger* dirty page allowance, but that it needs a *private* dirty page allowance, so that dirty pages for the "client" bdi that it is helping to clear (the bdi for an NFS filesystem or loop block device etc) do not affect the throttling of the daemon writing to the "final" bdi. This patch changes the heuristic so that the task is not throttled when the bdi it is writing to has a dirty page count below below (or equal to) the free-run threshold for that bdi. This ensures it will always be able to have some pages in flight, and so will not deadlock. In a steady-state, it is expected that PF_LOCAL_THROTTLE tasks might still be throttled by global threshold, but that is acceptable as it is only the deadlock state that is interesting for this flag. This approach of "only throttle when target bdi is busy" is consistent with the other use of PF_LESS_THROTTLE in current_may_throttle(), were it causes attention to be focussed only on the target bdi. So this patch - renames PF_LESS_THROTTLE to PF_LOCAL_THROTTLE, - removes the 25% bonus that that flag gives, and - If PF_LOCAL_THROTTLE is set, don't delay at all unless the global and the local free-run thresholds are exceeded. Note that previously realtime threads were treated the same as PF_LESS_THROTTLE threads. This patch does *not* change the behvaiour for real-time threads, so it is now different from the behaviour of nfsd and loop tasks. I don't know what is wanted for realtime. [akpm@linux-foundation.org: coding style fixes] Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Chuck Lever <chuck.lever@oracle.com> [nfsd] Cc: Christoph Hellwig <hch@lst.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Link: http://lkml.kernel.org/r/87ftbf7gs3.fsf@notabene.neil.brown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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17e34526 |
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07-May-2020 |
Qiwu Chen <qiwuchen55@gmail.com> |
mm/vmscan: remove unnecessary argument description of isolate_lru_pages() Since commit a9e7c39fa9fd9 ("mm/vmscan.c: remove 7th argument of isolate_lru_pages()"), the explanation of 'mode' argument has been unnecessary. Let's remove it. Signed-off-by: Qiwu Chen <chenqiwu@xiaomi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200501090346.2894-1-chenqiwu@xiaomi.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9de4f22a |
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06-Apr-2020 |
Huang Ying <ying.huang@intel.com> |
mm: code cleanup for MADV_FREE Some comments for MADV_FREE is revised and added to help people understand the MADV_FREE code, especially the page flag, PG_swapbacked. This makes page_is_file_cache() isn't consistent with its comments. So the function is renamed to page_is_file_lru() to make them consistent again. All these are put in one patch as one logical change. Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@kernel.org> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c4ecddff |
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01-Apr-2020 |
Mateusz Nosek <mateusznosek0@gmail.com> |
mm/vmscan.c: do_try_to_free_pages(): clean code by removing unnecessary assignment sc->memcg_low_skipped resets skipped_deactivate to 0 but this is not needed as this code path is never reachable with skipped_deactivate != 0 due to previous sc->skipped_deactivate branch. [mhocko@kernel.org: rewrite changelog] Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Link: http://lkml.kernel.org/r/20200319165938.23354-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4b793062 |
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01-Apr-2020 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: make may_enter_fs bool in shrink_page_list() This gives some size improvement: $size mm/vmscan.o (before) text data bss dec hex filename 53670 24123 12 77805 12fed mm/vmscan.o $size mm/vmscan.o (after) text data bss dec hex filename 53648 24123 12 77783 12fd7 mm/vmscan.o Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/Message-ID: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e072bff6 |
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01-Apr-2020 |
Mateusz Nosek <mateusznosek0@gmail.com> |
mm/vmscan.c: clean code by removing unnecessary assignment Previously 0 was assigned to variable 'lruvec_size', but the variable was never read later. So the assignment can be removed. Fixes: f87bccde6a7d ("mm/vmscan: remove unused lru_pages argument") Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: David Hildenbrand <david@redhat.com> Link: http://lkml.kernel.org/r/20200229214022.11853-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5644e1fb |
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01-Apr-2020 |
Qian Cai <cai@lca.pw> |
mm/vmscan.c: fix data races using kswapd_classzone_idx pgdat->kswapd_classzone_idx could be accessed concurrently in wakeup_kswapd(). Plain writes and reads without any lock protection result in data races. Fix them by adding a pair of READ|WRITE_ONCE() as well as saving a branch (compilers might well optimize the original code in an unintentional way anyway). While at it, also take care of pgdat->kswapd_order and non-kswapd threads in allow_direct_reclaim(). The data races were reported by KCSAN, BUG: KCSAN: data-race in wakeup_kswapd / wakeup_kswapd write to 0xffff9f427ffff2dc of 4 bytes by task 7454 on cpu 13: wakeup_kswapd+0xf1/0x400 wakeup_kswapd at mm/vmscan.c:3967 wake_all_kswapds+0x59/0xc0 wake_all_kswapds at mm/page_alloc.c:4241 __alloc_pages_slowpath+0xdcc/0x1290 __alloc_pages_slowpath at mm/page_alloc.c:4512 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x16e/0x6f0 __handle_mm_fault+0xcd5/0xd40 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 1 lock held by mtest01/7454: #0: ffff9f425afe8808 (&mm->mmap_sem#2){++++}, at: do_page_fault+0x143/0x6f9 do_user_addr_fault at arch/x86/mm/fault.c:1405 (inlined by) do_page_fault at arch/x86/mm/fault.c:1539 irq event stamp: 6944085 count_memcg_event_mm+0x1a6/0x270 count_memcg_event_mm+0x119/0x270 __do_softirq+0x34c/0x57c irq_exit+0xa2/0xc0 read to 0xffff9f427ffff2dc of 4 bytes by task 7472 on cpu 38: wakeup_kswapd+0xc8/0x400 wake_all_kswapds+0x59/0xc0 __alloc_pages_slowpath+0xdcc/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x16e/0x6f0 __handle_mm_fault+0xcd5/0xd40 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 1 lock held by mtest01/7472: #0: ffff9f425a9ac148 (&mm->mmap_sem#2){++++}, at: do_page_fault+0x143/0x6f9 irq event stamp: 6793561 count_memcg_event_mm+0x1a6/0x270 count_memcg_event_mm+0x119/0x270 __do_softirq+0x34c/0x57c irq_exit+0xa2/0xc0 BUG: KCSAN: data-race in kswapd / wakeup_kswapd write to 0xffff90973ffff2dc of 4 bytes by task 820 on cpu 6: kswapd+0x27c/0x8d0 kthread+0x1e0/0x200 ret_from_fork+0x27/0x50 read to 0xffff90973ffff2dc of 4 bytes by task 6299 on cpu 0: wakeup_kswapd+0xf3/0x450 wake_all_kswapds+0x59/0xc0 __alloc_pages_slowpath+0xdcc/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x170/0x700 __handle_mm_fault+0xc9f/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Cc: Matthew Wilcox <willy@infradead.org> Link: http://lkml.kernel.org/r/1582749472-5171-1-git-send-email-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6b700b5b |
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01-Apr-2020 |
Wei Yang <richardw.yang@linux.intel.com> |
mm/vmscan.c: remove cpu online notification for now kswapd kernel thread starts either with a CPU affinity set to the full cpu mask of its target node or without any affinity at all if the node is CPUless. There is a cpu hotplug callback (kswapd_cpu_online) that implements an elaborate way to update this mask when a cpu is onlined. It is not really clear whether there is any actual benefit from this scheme. Completely CPU-less NUMA nodes rarely gain a new CPU during runtime. Drop the code for that reason. If there is a real usecase then we can resurrect and simplify the code. [mhocko@suse.com rewrite changelog] Suggested-by: Michal Hocko <mhocko@suse.org> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/20200218224422.3407-1-richardw.yang@linux.intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f661d007 |
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01-Apr-2020 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: vmscan: replace open codings to NUMA_NO_NODE The commit 98fa15f34cb3 ("mm: replace all open encodings for NUMA_NO_NODE") did the replacement across the kernel tree, but we got some more in vmscan.c since then. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/1581568298-45317-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1eb6234e |
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01-Apr-2020 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: swap: make page_evictable() inline When backporting commit 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs") to our 4.9 kernel, our test bench noticed around 10% down with a couple of vm-scalability's test cases (lru-file-readonce, lru-file-readtwice and lru-file-mmap-read). I didn't see that much down on my VM (32c-64g-2nodes). It might be caused by the test configuration, which is 32c-256g with NUMA disabled and the tests were run in root memcg, so the tests actually stress only one inactive and active lru. It sounds not very usual in mordern production environment. That commit did two major changes: 1. Call page_evictable() 2. Use smp_mb to force the PG_lru set visible It looks they contribute the most overhead. The page_evictable() is a function which does function prologue and epilogue, and that was used by page reclaim path only. However, lru add is a very hot path, so it sounds better to make it inline. However, it calls page_mapping() which is not inlined either, but the disassemble shows it doesn't do push and pop operations and it sounds not very straightforward to inline it. Other than this, it sounds smp_mb() is not necessary for x86 since SetPageLRU is atomic which enforces memory barrier already, replace it with smp_mb__after_atomic() in the following patch. With the two fixes applied, the tests can get back around 5% on that test bench and get back normal on my VM. Since the test bench configuration is not that usual and I also saw around 6% up on the latest upstream, so it sounds good enough IMHO. The below is test data (lru-file-readtwice throughput) against the v5.6-rc4: mainline w/ inline fix 150MB 154MB With this patch the throughput gets 2.67% up. The data with using smp_mb__after_atomic() is showed in the following patch. Shakeel Butt did the below test: On a real machine with limiting the 'dd' on a single node and reading 100 GiB sparse file (less than a single node). Just ran a single instance to not cause the lru lock contention. The cmdline used is "dd if=file-100GiB of=/dev/null bs=4k". Ran the cmd 10 times with drop_caches in between and measured the time it took. Without patch: 56.64143 +- 0.672 sec With patches: 56.10 +- 0.21 sec [akpm@linux-foundation.org: move page_evictable() to internal.h] Fixes: 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs") Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: http://lkml.kernel.org/r/1584500541-46817-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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76073c64 |
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20-Feb-2020 |
Gavin Shan <gshan@redhat.com> |
mm/vmscan.c: don't round up scan size for online memory cgroup Commit 68600f623d69 ("mm: don't miss the last page because of round-off error") makes the scan size round up to @denominator regardless of the memory cgroup's state, online or offline. This affects the overall reclaiming behavior: the corresponding LRU list is eligible for reclaiming only when its size logically right shifted by @sc->priority is bigger than zero in the former formula. For example, the inactive anonymous LRU list should have at least 0x4000 pages to be eligible for reclaiming when we have 60/12 for swappiness/priority and without taking scan/rotation ratio into account. After the roundup is applied, the inactive anonymous LRU list becomes eligible for reclaiming when its size is bigger than or equal to 0x1000 in the same condition. (0x4000 >> 12) * 60 / (60 + 140 + 1) = 1 ((0x1000 >> 12) * 60) + 200) / (60 + 140 + 1) = 1 aarch64 has 512MB huge page size when the base page size is 64KB. The memory cgroup that has a huge page is always eligible for reclaiming in that case. The reclaiming is likely to stop after the huge page is reclaimed, meaing the further iteration on @sc->priority and the silbing and child memory cgroups will be skipped. The overall behaviour has been changed. This fixes the issue by applying the roundup to offlined memory cgroups only, to give more preference to reclaim memory from offlined memory cgroup. It sounds reasonable as those memory is unlikedly to be used by anyone. The issue was found by starting up 8 VMs on a Ampere Mustang machine, which has 8 CPUs and 16 GB memory. Each VM is given with 2 vCPUs and 2GB memory. It took 264 seconds for all VMs to be completely up and 784MB swap is consumed after that. With this patch applied, it took 236 seconds and 60MB swap to do same thing. So there is 10% performance improvement for my case. Note that KSM is disable while THP is enabled in the testing. total used free shared buff/cache available Mem: 16196 10065 2049 16 4081 3749 Swap: 8175 784 7391 total used free shared buff/cache available Mem: 16196 11324 3656 24 1215 2936 Swap: 8175 60 8115 Link: http://lkml.kernel.org/r/20200211024514.8730-1-gshan@redhat.com Fixes: 68600f623d69 ("mm: don't miss the last page because of round-off error") Signed-off-by: Gavin Shan <gshan@redhat.com> Acked-by: Roman Gushchin <guro@fb.com> Cc: <stable@vger.kernel.org> [4.20+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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648b5cf3 |
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30-Jan-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/vmscan: remove unused RECLAIM_OFF/RECLAIM_ZONE Commit 1b2ffb7896ad ("[PATCH] Zone reclaim: Allow modification of zone reclaim behavior")' defined RECLAIM_OFF/RECLAIM_ZONE, but never use them, so better to remove them. [dwagner@suse.de: fix sanity checks enabling] Link: http://lkml.kernel.org/r/20200116131642.642-1-dwagner@suse.de [akpm@linux-foundation.org: renumber the bits for neatness] Link: http://lkml.kernel.org/r/1579005573-58923-1-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Daniel Wagner <dwagner@suse.de> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: "Tobin C. Harding" <tobin@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fffbacc1 |
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30-Jan-2020 |
Alex Shi <alex.shi@linux.alibaba.com> |
mm/vmscan: remove prefetch_prev_lru_page This macro was never used in git history. So better to remove. Link: http://lkml.kernel.org/r/1579006500-127143-1-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6c9e0907 |
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30-Jan-2020 |
Liu Song <liu.song11@zte.com.cn> |
mm/vmscan.c: remove unused return value of shrink_node The return value of shrink_node is not used, so remove unnecessary operations. Link: http://lkml.kernel.org/r/20191128143524.3223-1-fishland@aliyun.com Signed-off-by: Liu Song <liu.song11@zte.com.cn> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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42a9a53b |
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17-Dec-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG Since commit 0a432dcbeb32 ("mm: shrinker: make shrinker not depend on memcg kmem"), shrinkers' idr is protected by CONFIG_MEMCG instead of CONFIG_MEMCG_KMEM, so it makes no sense to protect shrinker idr replace with CONFIG_MEMCG_KMEM. And in the CONFIG_MEMCG && CONFIG_SLOB case, shrinker_idr contains only shrinker, and it is deferred_split_shrinker. But it is never actually called, since idr_replace() is never compiled due to the wrong #ifdef. The deferred_split_shrinker all the time is staying in half-registered state, and it's never called for subordinate mem cgroups. Link: http://lkml.kernel.org/r/1575486978-45249-1-git-send-email-yang.shi@linux.alibaba.com Fixes: 0a432dcbeb32 ("mm: shrinker: make shrinker not depend on memcg kmem") Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Cc: <stable@vger.kernel.org> [5.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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178821b8 |
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30-Nov-2019 |
Xianting Tian <xianting_tian@126.com> |
mm/vmscan.c: fix typo in comment Fix the typo "resheduled" -> "rescheduled" in comment Link: http://lkml.kernel.org/r/1573486327-9591-1-git-send-email-xianting_tian@126.com Signed-off-by: Xianting Tian <xianting_tian@126.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b91ac374 |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: enforce inactive:active ratio at the reclaim root We split the LRU lists into inactive and an active parts to maximize workingset protection while allowing just enough inactive cache space to faciltate readahead and writeback for one-off file accesses (e.g. a linear scan through a file, or logging); or just enough inactive anon to maintain recent reference information when reclaim needs to swap. With cgroups and their nested LRU lists, we currently don't do this correctly. While recursive cgroup reclaim establishes a relative LRU order among the pages of all involved cgroups, inactive:active size decisions are done on a per-cgroup level. As a result, we'll reclaim a cgroup's workingset when it doesn't have cold pages, even when one of its siblings has plenty of it that should be reclaimed first. For example: workload A has 50M worth of hot cache but doesn't do any one-off file accesses; meanwhile, parallel workload B scans files and rarely accesses the same page twice. If these workloads were to run in an uncgrouped system, A would be protected from the high rate of cache faults from B. But if they were put in parallel cgroups for memory accounting purposes, B's fast cache fault rate would push out the hot cache pages of A. This is unexpected and undesirable - the "scan resistance" of the page cache is broken. This patch moves inactive:active size balancing decisions to the root of reclaim - the same level where the LRU order is established. It does this by looking at the recursive size of the inactive and the active file sets of the cgroup subtree at the beginning of the reclaim cycle, and then making a decision - scan or skip active pages - that applies throughout the entire run and to every cgroup involved. With that in place, in the test above, the VM will recognize that there are plenty of inactive pages in the combined cache set of workloads A and B and prefer the one-off cache in B over the hot pages in A. The scan resistance of the cache is restored. [cai@lca.pw: fix some -Wenum-conversion warnings] Link: http://lkml.kernel.org/r/1573848697-29262-1-git-send-email-cai@lca.pw Link: http://lkml.kernel.org/r/20191107205334.158354-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Rik van Riel <riel@surriel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b910718a |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: detect file thrashing at the reclaim root We use refault information to determine whether the cache workingset is stable or transitioning, and dynamically adjust the inactive:active file LRU ratio so as to maximize protection from one-off cache during stable periods, and minimize IO during transitions. With cgroups and their nested LRU lists, we currently don't do this correctly. While recursive cgroup reclaim establishes a relative LRU order among the pages of all involved cgroups, refaults only affect the local LRU order in the cgroup in which they are occuring. As a result, cache transitions can take longer in a cgrouped system as the active pages of sibling cgroups aren't challenged when they should be. [ Right now, this is somewhat theoretical, because the siblings, under continued regular reclaim pressure, should eventually run out of inactive pages - and since inactive:active *size* balancing is also done on a cgroup-local level, we will challenge the active pages eventually in most cases. But the next patch will move that relative size enforcement to the reclaim root as well, and then this patch here will be necessary to propagate refault pressure to siblings. ] This patch moves refault detection to the root of reclaim. Instead of remembering the cgroup owner of an evicted page, remember the cgroup that caused the reclaim to happen. When refaults later occur, they'll correctly influence the cross-cgroup LRU order that reclaim follows. I.e. if global reclaim kicked out pages in some subgroup A/B/C, the refault of those pages will challenge the global LRU order, and not just the local order down inside C. [hannes@cmpxchg.org: use page_memcg() instead of another lookup] Link: http://lkml.kernel.org/r/20191115160722.GA309754@cmpxchg.org Link: http://lkml.kernel.org/r/20191107205334.158354-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
53138cea |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: move file exhaustion detection to the node level Patch series "mm: fix page aging across multiple cgroups". When applications are put into unconfigured cgroups for memory accounting purposes, the cgrouping itself should not change the behavior of the page reclaim code. We expect the VM to reclaim the coldest pages in the system. But right now the VM can reclaim hot pages in one cgroup while there is eligible cold cache in others. This is because one part of the reclaim algorithm isn't truly cgroup hierarchy aware: the inactive/active list balancing. That is the part that is supposed to protect hot cache data from one-off streaming IO. The recursive cgroup reclaim scheme will scan and rotate the physical LRU lists of each eligible cgroup at the same rate in a round-robin fashion, thereby establishing a relative order among the pages of all those cgroups. However, the inactive/active balancing decisions are made locally within each cgroup, so when a cgroup is running low on cold pages, its hot pages will get reclaimed - even when sibling cgroups have plenty of cold cache eligible in the same reclaim run. For example: [root@ham ~]# head -n1 /proc/meminfo MemTotal: 1016336 kB [root@ham ~]# ./reclaimtest2.sh Establishing 50M active files in cgroup A... Hot pages cached: 12800/12800 workingset-a Linearly scanning through 18G of file data in cgroup B: real 0m4.269s user 0m0.051s sys 0m4.182s Hot pages cached: 134/12800 workingset-a The streaming IO in B, which doesn't benefit from caching at all, pushes out most of the workingset in A. Solution This series fixes the problem by elevating inactive/active balancing decisions to the toplevel of the reclaim run. This is either a cgroup that hit its limit, or straight-up global reclaim if there is physical memory pressure. From there, it takes a recursive view of the cgroup subtree to decide whether page deactivation is necessary. In the test above, the VM will then recognize that cgroup B has plenty of eligible cold cache, and that the hot pages in A can be spared: [root@ham ~]# ./reclaimtest2.sh Establishing 50M active files in cgroup A... Hot pages cached: 12800/12800 workingset-a Linearly scanning through 18G of file data in cgroup B: real 0m4.244s user 0m0.064s sys 0m4.177s Hot pages cached: 12800/12800 workingset-a Implementation Whether active pages can be deactivated or not is influenced by two factors: the inactive list dropping below a minimum size relative to the active list, and the occurence of refaults. This patch series first moves refault detection to the reclaim root, then enforces the minimum inactive size based on a recursive view of the cgroup tree's LRUs. History Note that this actually never worked correctly in Linux cgroups. In the past it worked for global reclaim and leaf limit reclaim only (we used to have two physical LRU linkages per page), but it never worked for intermediate limit reclaim over multiple leaf cgroups. We're noticing this now because 1) we're putting everything into cgroups for accounting, not just the things we want to control and 2) we're moving away from leaf limits that invoke reclaim on individual cgroups, toward large tree reclaim, triggered by high-level limits, or physical memory pressure that is influenced by local protections such as memory.low and memory.min instead. This patch (of 3): When file pages are lower than the watermark on a node, we try to force scan anonymous pages to counter-act the balancing algorithms preference for new file pages when they are likely thrashing. This is a node-level decision, but it's currently made each time we look at an lruvec. This is unnecessarily expensive and also a layering violation that makes the code harder to understand. Clean this up by making the check once per node and setting a flag in the scan_control. Link: http://lkml.kernel.org/r/20191107205334.158354-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1b05117d |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: harmonize writeback congestion tracking for nodes & memcgs The current writeback congestion tracking has separate flags for kswapd reclaim (node level) and cgroup limit reclaim (memcg-node level). This is unnecessarily complicated: the lruvec is an existing abstraction layer for that node-memcg intersection. Introduce lruvec->flags and LRUVEC_CONGESTED. Then track that at the reclaim root level, which is either the NUMA node for global reclaim, or the cgroup-node intersection for cgroup reclaim. Link: http://lkml.kernel.org/r/20191022144803.302233-9-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0f6a5cff |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: split shrink_node() into node part and memcgs part This function is getting long and unwieldy, split out the memcg bits. The updated shrink_node() handles the generic (node) reclaim aspects: - global vmpressure notifications - writeback and congestion throttling - reclaim/compaction management - kswapd giving up on unreclaimable nodes It then calls a new shrink_node_memcgs() which handles cgroup specifics: - the cgroup tree traversal - memory.low considerations - per-cgroup slab shrinking callbacks - per-cgroup vmpressure notifications [hannes@cmpxchg.org: rename "root" to "target_memcg", per Roman] Link: http://lkml.kernel.org/r/20191025143640.GA386981@cmpxchg.org Link: http://lkml.kernel.org/r/20191022144803.302233-8-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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afaf07a6 |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: turn shrink_node_memcg() into shrink_lruvec() An lruvec holds LRU pages owned by a certain NUMA node and cgroup. Instead of awkwardly passing around a combination of a pgdat and a memcg pointer, pass down the lruvec as soon as we can look it up. Nested callers that need to access node or cgroup properties can look them them up if necessary, but there are only a few cases. Link: http://lkml.kernel.org/r/20191022144803.302233-7-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d2af3397 |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: replace shrink_node() loop with a retry jump Most of the function body is inside a loop, which imposes an additional indentation and scoping level that makes the code a bit hard to follow and modify. The looping only happens in case of reclaim-compaction, which isn't the common case. So rather than adding yet another function level to the reclaim path and have every reclaim invocation go through a level that only exists for one specific cornercase, use a retry goto. Link: http://lkml.kernel.org/r/20191022144803.302233-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b5ead35e |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: naming fixes: global_reclaim() and sane_reclaim() Seven years after introducing the global_reclaim() function, I still have to double take when reading a callsite. I don't know how others do it, this is a terrible name. Invert the meaning and rename it to cgroup_reclaim(). [ After all, "global reclaim" is just regular reclaim invoked from the page allocator. It's reclaim on behalf of a cgroup limit that is a special case of reclaim, and should be explicit - not the reverse. ] sane_reclaim() isn't very descriptive either: it tests whether we can use the regular writeback throttling - available during regular page reclaim or cgroup2 limit reclaim - or need to use the broken wait_on_page_writeback() method. Use "writeback_throttling_sane()". Link: http://lkml.kernel.org/r/20191022144803.302233-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a1086291 |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: move inactive_list_is_low() swap check to the caller inactive_list_is_low() should be about one thing: checking the ratio between inactive and active list. Kitchensink checks like the one for swap space makes the function hard to use and modify its callsites. Luckly, most callers already have an understanding of the swap situation, so it's easy to clean up. get_scan_count() has its own, memcg-aware swap check, and doesn't even get to the inactive_list_is_low() check on the anon list when there is no swap space available. shrink_list() is called on the results of get_scan_count(), so that check is redundant too. age_active_anon() has its own totalswap_pages check right before it checks the list proportions. The shrink_node_memcg() site is the only one that doesn't do its own swap check. Add it there. Then delete the swap check from inactive_list_is_low(). Link: http://lkml.kernel.org/r/20191022144803.302233-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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867e5e1d |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: clean up and clarify lruvec lookup procedure There is a per-memcg lruvec and a NUMA node lruvec. Which one is being used is somewhat confusing right now, and it's easy to make mistakes - especially when it comes to global reclaim. How it works: when memory cgroups are enabled, we always use the root_mem_cgroup's per-node lruvecs. When memory cgroups are not compiled in or disabled at runtime, we use pgdat->lruvec. Document that in a comment. Due to the way the reclaim code is generalized, all lookups use the mem_cgroup_lruvec() helper function, and nobody should have to find the right lruvec manually right now. But to avoid future mistakes, rename the pgdat->lruvec member to pgdat->__lruvec and delete the convenience wrapper that suggests it's a commonly accessed member. While in this area, swap the mem_cgroup_lruvec() argument order. The name suggests a memcg operation, yet it takes a pgdat first and a memcg second. I have to double take every time I call this. Fix that. Link: http://lkml.kernel.org/r/20191022144803.302233-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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de3b0150 |
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30-Nov-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: simplify lruvec_lru_size() Patch series "mm: vmscan: cgroup-related cleanups". Here are 8 patches that clean up the reclaim code's interaction with cgroups a bit. They're not supposed to change any behavior, just make the implementation easier to understand and work with. This patch (of 8): This function currently takes the node or lruvec size and subtracts the zones that are excluded by the classzone index of the allocation. It uses four different types of counters to do this. Just add up the eligible zones. [cai@lca.pw: fix an undefined behavior for zone id] Link: http://lkml.kernel.org/r/20191108204407.1435-1-cai@lca.pw [akpm@linux-foundation.org: deal with the MAX_NR_ZONES special case. per Qian Cai] Link: http://lkml.kernel.org/r/64E60F6F-7582-427B-8DD5-EF97B1656F5A@lca.pw Link: http://lkml.kernel.org/r/20191022144803.302233-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cb16556d |
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30-Nov-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm/vmscan.c: remove unused scan_control parameter from pageout() Since lumpy reclaim was removed in v3.5 scan_control is not used by may_write_to_{queue|inode} and pageout() anymore, remove the unused parameter. Link: http://lkml.kernel.org/r/1570124498-19300-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f87bccde |
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30-Nov-2019 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/vmscan: remove unused lru_pages argument Since 9092c71bb724 ("mm: use sc->priority for slab shrink targets") the argument 'unsigned long *lru_pages' passed around with no purpose. Remove it. Link: http://lkml.kernel.org/r/20190228083329.31892-4-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fa40d1ee |
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30-Nov-2019 |
Shakeel Butt <shakeelb@google.com> |
mm: vmscan: memcontrol: remove mem_cgroup_select_victim_node() Since commit 1ba6fc9af35b ("mm: vmscan: do not share cgroup iteration between reclaimers"), the memcg reclaim does not bail out earlier based on sc->nr_reclaimed and will traverse all the nodes. All the reclaimable pages of the memcg on all the nodes will be scanned relative to the reclaim priority. So, there is no need to maintain state regarding which node to start the memcg reclaim from. This patch effectively reverts the commit 889976dbcb12 ("memcg: reclaim memory from nodes in round-robin order") and commit 453a9bf347f1 ("memcg: fix numa scan information update to be triggered by memory event"). [shakeelb@google.com: v2] Link: http://lkml.kernel.org/r/20191030204232.139424-1-shakeelb@google.com Link: http://lkml.kernel.org/r/20191029234753.224143-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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906d278d |
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18-Oct-2019 |
William Kucharski <william.kucharski@oracle.com> |
mm/vmscan.c: support removing arbitrary sized pages from mapping __remove_mapping() assumes that pages can only be either base pages or HPAGE_PMD_SIZE. Ask the page what size it is. Link: http://lkml.kernel.org/r/20191017164223.2762148-4-songliubraving@fb.com Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Signed-off-by: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Song Liu <songliubraving@fb.com> Acked-by: Yang Shi <yang.shi@linux.alibaba.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b11edebb |
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18-Oct-2019 |
Honglei Wang <honglei.wang@oracle.com> |
mm: memcg: get number of pages on the LRU list in memcgroup base on lru_zone_size Commit 1a61ab8038e72 ("mm: memcontrol: replace zone summing with lruvec_page_state()") has made lruvec_page_state to use per-cpu counters instead of calculating it directly from lru_zone_size with an idea that this would be more effective. Tim has reported that this is not really the case for their database benchmark which is showing an opposite results where lruvec_page_state is taking up a huge chunk of CPU cycles (about 25% of the system time which is roughly 7% of total cpu cycles) on 5.3 kernels. The workload is running on a larger machine (96cpus), it has many cgroups (500) and it is heavily direct reclaim bound. Tim Chen said: : The problem can also be reproduced by running simple multi-threaded : pmbench benchmark with a fast Optane SSD swap (see profile below). : : : 6.15% 3.08% pmbench [kernel.vmlinux] [k] lruvec_lru_size : | : |--3.07%--lruvec_lru_size : | | : | |--2.11%--cpumask_next : | | | : | | --1.66%--find_next_bit : | | : | --0.57%--call_function_interrupt : | | : | --0.55%--smp_call_function_interrupt : | : |--1.59%--0x441f0fc3d009 : | _ops_rdtsc_init_base_freq : | access_histogram : | page_fault : | __do_page_fault : | handle_mm_fault : | __handle_mm_fault : | | : | --1.54%--do_swap_page : | swapin_readahead : | swap_cluster_readahead : | | : | --1.53%--read_swap_cache_async : | __read_swap_cache_async : | alloc_pages_vma : | __alloc_pages_nodemask : | __alloc_pages_slowpath : | try_to_free_pages : | do_try_to_free_pages : | shrink_node : | shrink_node_memcg : | | : | |--0.77%--lruvec_lru_size : | | : | --0.76%--inactive_list_is_low : | | : | --0.76%--lruvec_lru_size : | : --1.50%--measure_read : page_fault : __do_page_fault : handle_mm_fault : __handle_mm_fault : do_swap_page : swapin_readahead : swap_cluster_readahead : | : --1.48%--read_swap_cache_async : __read_swap_cache_async : alloc_pages_vma : __alloc_pages_nodemask : __alloc_pages_slowpath : try_to_free_pages : do_try_to_free_pages : shrink_node : shrink_node_memcg : | : |--0.75%--inactive_list_is_low : | | : | --0.75%--lruvec_lru_size : | : --0.73%--lruvec_lru_size The likely culprit is the cache traffic the lruvec_page_state_local generates. Dave Hansen says: : I was thinking purely of the cache footprint. If it's reading : pn->lruvec_stat_local->count[idx] is three separate cachelines, so 192 : bytes of cache *96 CPUs = 18k of data, mostly read-only. 1 cgroup would : be 18k of data for the whole system and the caching would be pretty : efficient and all 18k would probably survive a tight page fault loop in : the L1. 500 cgroups would be ~90k of data per CPU thread which doesn't : fit in the L1 and probably wouldn't survive a tight page fault loop if : both logical threads were banging on different cgroups. : : It's just a theory, but it's why I noted the number of cgroups when I : initially saw this show up in profiles Fix the regression by partially reverting the said commit and calculate the lru size explicitly. Link: http://lkml.kernel.org/r/20190905071034.16822-1-honglei.wang@oracle.com Fixes: 1a61ab8038e72 ("mm: memcontrol: replace zone summing with lruvec_page_state()") Signed-off-by: Honglei Wang <honglei.wang@oracle.com> Reported-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Tested-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <guro@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: <stable@vger.kernel.org> [5.2+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1bc63fb1 |
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06-Oct-2019 |
Chris Down <chris@chrisdown.name> |
mm, memcg: make scan aggression always exclude protection This patch is an incremental improvement on the existing memory.{low,min} relative reclaim work to base its scan pressure calculations on how much protection is available compared to the current usage, rather than how much the current usage is over some protection threshold. This change doesn't change the experience for the user in the normal case too much. One benefit is that it replaces the (somewhat arbitrary) 100% cutoff with an indefinite slope, which makes it easier to ballpark a memory.low value. As well as this, the old methodology doesn't quite apply generically to machines with varying amounts of physical memory. Let's say we have a top level cgroup, workload.slice, and another top level cgroup, system-management.slice. We want to roughly give 12G to system-management.slice, so on a 32GB machine we set memory.low to 20GB in workload.slice, and on a 64GB machine we set memory.low to 52GB. However, because these are relative amounts to the total machine size, while the amount of memory we want to generally be willing to yield to system.slice is absolute (12G), we end up putting more pressure on system.slice just because we have a larger machine and a larger workload to fill it, which seems fairly unintuitive. With this new behaviour, we don't end up with this unintended side effect. Previously the way that memory.low protection works is that if you are 50% over a certain baseline, you get 50% of your normal scan pressure. This is certainly better than the previous cliff-edge behaviour, but it can be improved even further by always considering memory under the currently enforced protection threshold to be out of bounds. This means that we can set relatively low memory.low thresholds for variable or bursty workloads while still getting a reasonable level of protection, whereas with the previous version we may still trivially hit the 100% clamp. The previous 100% clamp is also somewhat arbitrary, whereas this one is more concretely based on the currently enforced protection threshold, which is likely easier to reason about. There is also a subtle issue with the way that proportional reclaim worked previously -- it promotes having no memory.low, since it makes pressure higher during low reclaim. This happens because we base our scan pressure modulation on how far memory.current is between memory.min and memory.low, but if memory.low is unset, we only use the overage method. In most cromulent configurations, this then means that we end up with *more* pressure than with no memory.low at all when we're in low reclaim, which is not really very usable or expected. With this patch, memory.low and memory.min affect reclaim pressure in a more understandable and composable way. For example, from a user standpoint, "protected" memory now remains untouchable from a reclaim aggression standpoint, and users can also have more confidence that bursty workloads will still receive some amount of guaranteed protection. Link: http://lkml.kernel.org/r/20190322160307.GA3316@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Reviewed-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9de7ca46 |
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06-Oct-2019 |
Chris Down <chris@chrisdown.name> |
mm, memcg: make memory.emin the baseline for utilisation determination Roman points out that when when we do the low reclaim pass, we scale the reclaim pressure relative to position between 0 and the maximum protection threshold. However, if the maximum protection is based on memory.elow, and memory.emin is above zero, this means we still may get binary behaviour on second-pass low reclaim. This is because we scale starting at 0, not starting at memory.emin, and since we don't scan at all below emin, we end up with cliff behaviour. This should be a fairly uncommon case since usually we don't go into the second pass, but it makes sense to scale our low reclaim pressure starting at emin. You can test this by catting two large sparse files, one in a cgroup with emin set to some moderate size compared to physical RAM, and another cgroup without any emin. In both cgroups, set an elow larger than 50% of physical RAM. The one with emin will have less page scanning, as reclaim pressure is lower. Rebase on top of and apply the same idea as what was applied to handle cgroup_memory=disable properly for the original proportional patch http://lkml.kernel.org/r/20190201045711.GA18302@chrisdown.name ("mm, memcg: Handle cgroup_disable=memory when getting memcg protection"). Link: http://lkml.kernel.org/r/20190201051810.GA18895@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Suggested-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9783aa99 |
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06-Oct-2019 |
Chris Down <chris@chrisdown.name> |
mm, memcg: proportional memory.{low,min} reclaim cgroup v2 introduces two memory protection thresholds: memory.low (best-effort) and memory.min (hard protection). While they generally do what they say on the tin, there is a limitation in their implementation that makes them difficult to use effectively: that cliff behaviour often manifests when they become eligible for reclaim. This patch implements more intuitive and usable behaviour, where we gradually mount more reclaim pressure as cgroups further and further exceed their protection thresholds. This cliff edge behaviour happens because we only choose whether or not to reclaim based on whether the memcg is within its protection limits (see the use of mem_cgroup_protected in shrink_node), but we don't vary our reclaim behaviour based on this information. Imagine the following timeline, with the numbers the lruvec size in this zone: 1. memory.low=1000000, memory.current=999999. 0 pages may be scanned. 2. memory.low=1000000, memory.current=1000000. 0 pages may be scanned. 3. memory.low=1000000, memory.current=1000001. 1000001* pages may be scanned. (?!) * Of course, we won't usually scan all available pages in the zone even without this patch because of scan control priority, over-reclaim protection, etc. However, as shown by the tests at the end, these techniques don't sufficiently throttle such an extreme change in input, so cliff-like behaviour isn't really averted by their existence alone. Here's an example of how this plays out in practice. At Facebook, we are trying to protect various workloads from "system" software, like configuration management tools, metric collectors, etc (see this[0] case study). In order to find a suitable memory.low value, we start by determining the expected memory range within which the workload will be comfortable operating. This isn't an exact science -- memory usage deemed "comfortable" will vary over time due to user behaviour, differences in composition of work, etc, etc. As such we need to ballpark memory.low, but doing this is currently problematic: 1. If we end up setting it too low for the workload, it won't have *any* effect (see discussion above). The group will receive the full weight of reclaim and won't have any priority while competing with the less important system software, as if we had no memory.low configured at all. 2. Because of this behaviour, we end up erring on the side of setting it too high, such that the comfort range is reliably covered. However, protected memory is completely unavailable to the rest of the system, so we might cause undue memory and IO pressure there when we *know* we have some elasticity in the workload. 3. Even if we get the value totally right, smack in the middle of the comfort zone, we get extreme jumps between no pressure and full pressure that cause unpredictable pressure spikes in the workload due to the current binary reclaim behaviour. With this patch, we can set it to our ballpark estimation without too much worry. Any undesirable behaviour, such as too much or too little reclaim pressure on the workload or system will be proportional to how far our estimation is off. This means we can set memory.low much more conservatively and thus waste less resources *without* the risk of the workload falling off a cliff if we overshoot. As a more abstract technical description, this unintuitive behaviour results in having to give high-priority workloads a large protection buffer on top of their expected usage to function reliably, as otherwise we have abrupt periods of dramatically increased memory pressure which hamper performance. Having to set these thresholds so high wastes resources and generally works against the principle of work conservation. In addition, having proportional memory reclaim behaviour has other benefits. Most notably, before this patch it's basically mandatory to set memory.low to a higher than desirable value because otherwise as soon as you exceed memory.low, all protection is lost, and all pages are eligible to scan again. By contrast, having a gradual ramp in reclaim pressure means that you now still get some protection when thresholds are exceeded, which means that one can now be more comfortable setting memory.low to lower values without worrying that all protection will be lost. This is important because workingset size is really hard to know exactly, especially with variable workloads, so at least getting *some* protection if your workingset size grows larger than you expect increases user confidence in setting memory.low without a huge buffer on top being needed. Thanks a lot to Johannes Weiner and Tejun Heo for their advice and assistance in thinking about how to make this work better. In testing these changes, I intended to verify that: 1. Changes in page scanning become gradual and proportional instead of binary. To test this, I experimented stepping further and further down memory.low protection on a workload that floats around 19G workingset when under memory.low protection, watching page scan rates for the workload cgroup: +------------+-----------------+--------------------+--------------+ | memory.low | test (pgscan/s) | control (pgscan/s) | % of control | +------------+-----------------+--------------------+--------------+ | 21G | 0 | 0 | N/A | | 17G | 867 | 3799 | 23% | | 12G | 1203 | 3543 | 34% | | 8G | 2534 | 3979 | 64% | | 4G | 3980 | 4147 | 96% | | 0 | 3799 | 3980 | 95% | +------------+-----------------+--------------------+--------------+ As you can see, the test kernel (with a kernel containing this patch) ramps up page scanning significantly more gradually than the control kernel (without this patch). 2. More gradual ramp up in reclaim aggression doesn't result in premature OOMs. To test this, I wrote a script that slowly increments the number of pages held by stress(1)'s --vm-keep mode until a production system entered severe overall memory contention. This script runs in a highly protected slice taking up the majority of available system memory. Watching vmstat revealed that page scanning continued essentially nominally between test and control, without causing forward reclaim progress to become arrested. [0]: https://facebookmicrosites.github.io/cgroup2/docs/overview.html#case-study-the-fbtax2-project [akpm@linux-foundation.org: reflow block comments to fit in 80 cols] [chris@chrisdown.name: handle cgroup_disable=memory when getting memcg protection] Link: http://lkml.kernel.org/r/20190201045711.GA18302@chrisdown.name Link: http://lkml.kernel.org/r/20190124014455.GA6396@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1a4e58cc |
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25-Sep-2019 |
Minchan Kim <minchan@kernel.org> |
mm: introduce MADV_PAGEOUT When a process expects no accesses to a certain memory range for a long time, it could hint kernel that the pages can be reclaimed instantly but data should be preserved for future use. This could reduce workingset eviction so it ends up increasing performance. This patch introduces the new MADV_PAGEOUT hint to madvise(2) syscall. MADV_PAGEOUT can be used by a process to mark a memory range as not expected to be used for a long time so that kernel reclaims *any LRU* pages instantly. The hint can help kernel in deciding which pages to evict proactively. A note: It doesn't apply SWAP_CLUSTER_MAX LRU page isolation limit intentionally because it's automatically bounded by PMD size. If PMD size(e.g., 256) makes some trouble, we could fix it later by limit it to SWAP_CLUSTER_MAX[1]. - man-page material MADV_PAGEOUT (since Linux x.x) Do not expect access in the near future so pages in the specified regions could be reclaimed instantly regardless of memory pressure. Thus, access in the range after successful operation could cause major page fault but never lose the up-to-date contents unlike MADV_DONTNEED. Pages belonging to a shared mapping are only processed if a write access is allowed for the calling process. MADV_PAGEOUT cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP pages. [1] https://lore.kernel.org/lkml/20190710194719.GS29695@dhcp22.suse.cz/ [minchan@kernel.org: clear PG_active on MADV_PAGEOUT] Link: http://lkml.kernel.org/r/20190802200643.GA181880@google.com [akpm@linux-foundation.org: resolve conflicts with hmm.git] Link: http://lkml.kernel.org/r/20190726023435.214162-5-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: kbuild test robot <lkp@intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Chris Zankel <chris@zankel.net> Cc: Daniel Colascione <dancol@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Oleksandr Natalenko <oleksandr@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tim Murray <timmurray@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8940b34a |
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25-Sep-2019 |
Minchan Kim <minchan@kernel.org> |
mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM The local variable references in shrink_page_list is PAGEREF_RECLAIM_CLEAN as default. It is for preventing to reclaim dirty pages when CMA try to migrate pages. Strictly speaking, we don't need it because CMA didn't allow to write out by .may_writepage = 0 in reclaim_clean_pages_from_list. Moreover, it has a problem to prevent anonymous pages's swap out even though force_reclaim = true in shrink_page_list on upcoming patch. So this patch makes references's default value to PAGEREF_RECLAIM and rename force_reclaim with ignore_references to make it more clear. This is a preparatory work for next patch. Link: http://lkml.kernel.org/r/20190726023435.214162-3-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Chris Zankel <chris@zankel.net> Cc: Daniel Colascione <dancol@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: kbuild test robot <lkp@intel.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Oleksandr Natalenko <oleksandr@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tim Murray <timmurray@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0a432dcb |
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23-Sep-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: shrinker: make shrinker not depend on memcg kmem Currently shrinker is just allocated and can work when memcg kmem is enabled. But, THP deferred split shrinker is not slab shrinker, it doesn't make too much sense to have such shrinker depend on memcg kmem. It should be able to reclaim THP even though memcg kmem is disabled. Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker. When memcg kmem is disabled, just such shrinkers can be called in shrinking memcg slab. [yang.shi@linux.alibaba.com: add comment] Link: http://lkml.kernel.org/r/1566496227-84952-4-git-send-email-yang.shi@linux.alibaba.com Link: http://lkml.kernel.org/r/1565144277-36240-4-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7ae88534 |
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23-Sep-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: move mem_cgroup_uncharge out of __page_cache_release() A later patch makes THP deferred split shrinker memcg aware, but it needs page->mem_cgroup information in THP destructor, which is called after mem_cgroup_uncharge() now. So move mem_cgroup_uncharge() from __page_cache_release() to compound page destructor, which is called by both THP and other compound pages except HugeTLB. And call it in __put_single_page() for single order page. Link: http://lkml.kernel.org/r/1565144277-36240-3-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5ee04716 |
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23-Sep-2019 |
Vlastimil Babka <vbabka@suse.cz> |
mm, reclaim: cleanup should_continue_reclaim() After commit "mm, reclaim: make should_continue_reclaim perform dryrun detection", closer look at the function shows, that nr_reclaimed == 0 means the function will always return false. And since non-zero nr_reclaimed implies non_zero nr_scanned, testing nr_scanned serves no purpose, and so does the testing for __GFP_RETRY_MAYFAIL. This patch thus cleans up the function to test only !nr_reclaimed upfront, and remove the __GFP_RETRY_MAYFAIL test and nr_scanned parameter completely. Comment is also updated, explaining that approximating "full LRU list has been scanned" with nr_scanned == 0 didn't really work. Link: http://lkml.kernel.org/r/20190806014744.15446-3-mike.kravetz@oracle.com Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1c6c1597 |
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23-Sep-2019 |
Hillf Danton <hdanton@sina.com> |
mm, reclaim: make should_continue_reclaim perform dryrun detection Patch series "address hugetlb page allocation stalls", v2. Allocation of hugetlb pages via sysctl or procfs can stall for minutes or hours. A simple example on a two node system with 8GB of memory is as follows: echo 4096 > /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages echo 4096 > /proc/sys/vm/nr_hugepages Obviously, both allocation attempts will fall short of their 8GB goal. However, one or both of these commands may stall and not be interruptible. The issues were initially discussed in mail thread [1] and RFC code at [2]. This series addresses the issues causing the stalls. There are two distinct fixes, a cleanup, and an optimization. The reclaim patch by Hillf and compaction patch by Vlasitmil address corner cases in their respective areas. hugetlb page allocation could stall due to either of these issues. Vlasitmil added a cleanup patch after Hillf's modifications. The hugetlb patch by Mike is an optimization suggested during the debug and development process. [1] http://lkml.kernel.org/r/d38a095e-dc39-7e82-bb76-2c9247929f07@oracle.com [2] http://lkml.kernel.org/r/20190724175014.9935-1-mike.kravetz@oracle.com This patch (of 4): Address the issue of should_continue_reclaim returning true too often for __GFP_RETRY_MAYFAIL attempts when !nr_reclaimed and nr_scanned. This was observed during hugetlb page allocation causing stalls for minutes or hours. We can stop reclaiming pages if compaction reports it can make a progress. There might be side-effects for other high-order allocations that would potentially benefit from reclaiming more before compaction so that they would be faster and less likely to stall. However, the consequences of premature/over-reclaim are considered worse. We can also bail out of reclaiming pages if we know that there are not enough inactive lru pages left to satisfy the costly allocation. We can give up reclaiming pages too if we see dryrun occur, with the certainty of plenty of inactive pages. IOW with dryrun detected, we are sure we have reclaimed as many pages as we could. Link: http://lkml.kernel.org/r/20190806014744.15446-2-mike.kravetz@oracle.com Signed-off-by: Hillf Danton <hdanton@sina.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1ba6fc9a |
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23-Sep-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: do not share cgroup iteration between reclaimers One of our services observed a high rate of cgroup OOM kills in the presence of large amounts of clean cache. Debugging showed that the culprit is the shared cgroup iteration in page reclaim. Under high allocation concurrency, multiple threads enter reclaim at the same time. Fearing overreclaim when we first switched from the single global LRU to cgrouped LRU lists, we introduced a shared iteration state for reclaim invocations - whether 1 or 20 reclaimers are active concurrently, we only walk the cgroup tree once: the 1st reclaimer reclaims the first cgroup, the second the second one etc. With more reclaimers than cgroups, we start another walk from the top. This sounded reasonable at the time, but the problem is that reclaim concurrency doesn't scale with allocation concurrency. As reclaim concurrency increases, the amount of memory individual reclaimers get to scan gets smaller and smaller. Individual reclaimers may only see one cgroup per cycle, and that may not have much reclaimable memory. We see individual reclaimers declare OOM when there is plenty of reclaimable memory available in cgroups they didn't visit. This patch does away with the shared iterator, and every reclaimer is allowed to scan the full cgroup tree and see all of reclaimable memory, just like it would on a non-cgrouped system. This way, when OOM is declared, we know that the reclaimer actually had a chance. To still maintain fairness in reclaim pressure, disallow cgroup reclaim from bailing out of the tree walk early. Kswapd and regular direct reclaim already don't bail, so it's not clear why limit reclaim would have to, especially since it only walks subtrees to begin with. This change completely eliminates the OOM kills on our service, while showing no signs of overreclaim - no increased scan rates, %sys time, or abrupt free memory spikes. I tested across 100 machines that have 64G of RAM and host about 300 cgroups each. [ It's possible overreclaim never was a *practical* issue to begin with - it was simply a concern we had on the mailing lists at the time, with no real data to back it up. But we have also added more bail-out conditions deeper inside reclaim (e.g. the proportional exit in shrink_node_memcg) since. Regardless, now we have data that suggests full walks are more reliable and scale just fine. ] Link: http://lkml.kernel.org/r/20190812192316.13615-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d8c6546b |
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23-Sep-2019 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: introduce compound_nr() Replace 1 << compound_order(page) with compound_nr(page). Minor improvements in readability. Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d2e5fb92 |
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30-Aug-2019 |
Michal Hocko <mhocko@suse.com> |
mm, memcg: do not set reclaim_state on soft limit reclaim Adric Blake has noticed[1] the following warning: WARNING: CPU: 7 PID: 175 at mm/vmscan.c:245 set_task_reclaim_state+0x1e/0x40 [...] Call Trace: mem_cgroup_shrink_node+0x9b/0x1d0 mem_cgroup_soft_limit_reclaim+0x10c/0x3a0 balance_pgdat+0x276/0x540 kswapd+0x200/0x3f0 ? wait_woken+0x80/0x80 kthread+0xfd/0x130 ? balance_pgdat+0x540/0x540 ? kthread_park+0x80/0x80 ret_from_fork+0x35/0x40 ---[ end trace 727343df67b2398a ]--- which tells us that soft limit reclaim is about to overwrite the reclaim_state configured up in the call chain (kswapd in this case but the direct reclaim is equally possible). This means that reclaim stats would get misleading once the soft reclaim returns and another reclaim is done. Fix the warning by dropping set_task_reclaim_state from the soft reclaim which is always called with reclaim_state set up. [1] http://lkml.kernel.org/r/CAE1jjeePxYPvw1mw2B3v803xHVR_BNnz0hQUY_JDMN8ny29M6w@mail.gmail.com Link: http://lkml.kernel.org/r/20190828071808.20410-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Adric Blake <promarbler14@gmail.com> Acked-by: Yafang Shao <laoar.shao@gmail.com> Acked-by: Yang Shi <yang.shi@linux.alibaba.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hdanton@sina.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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28360f39 |
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13-Aug-2019 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: do not special-case slab reclaim when watermarks are boosted Dave Chinner reported a problem pointing a finger at commit 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs"). The report is extensive: https://lore.kernel.org/linux-mm/20190807091858.2857-1-david@fromorbit.com/ and it's worth recording the most relevant parts (colorful language and typos included). When running a simple, steady state 4kB file creation test to simulate extracting tarballs larger than memory full of small files into the filesystem, I noticed that once memory fills up the cache balance goes to hell. The workload is creating one dirty cached inode for every dirty page, both of which should require a single IO each to clean and reclaim, and creation of inodes is throttled by the rate at which dirty writeback runs at (via balance dirty pages). Hence the ingest rate of new cached inodes and page cache pages is identical and steady. As a result, memory reclaim should quickly find a steady balance between page cache and inode caches. The moment memory fills, the page cache is reclaimed at a much faster rate than the inode cache, and evidence suggests that the inode cache shrinker is not being called when large batches of pages are being reclaimed. In roughly the same time period that it takes to fill memory with 50% pages and 50% slab caches, memory reclaim reduces the page cache down to just dirty pages and slab caches fill the entirety of memory. The LRU is largely full of dirty pages, and we're getting spikes of random writeback from memory reclaim so it's all going to shit. Behaviour never recovers, the page cache remains pinned at just dirty pages, and nothing I could tune would make any difference. vfs_cache_pressure makes no difference - I would set it so high it should trim the entire inode caches in a single pass, yet it didn't do anything. It was clear from tracing and live telemetry that the shrinkers were pretty much not running except when there was absolutely no memory free at all, and then they did the minimum necessary to free memory to make progress. So I went looking at the code, trying to find places where pages got reclaimed and the shrinkers weren't called. There's only one - kswapd doing boosted reclaim as per commit 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs"). The watermark boosting introduced by the commit is triggered in response to an allocation "fragmentation event". The boosting was not intended to target THP specifically and triggers even if THP is disabled. However, with Dave's perfectly reasonable workload, fragmentation events can be very common given the ratio of slab to page cache allocations so boosting remains active for long periods of time. As high-order allocations might use compaction and compaction cannot move slab pages the decision was made in the commit to special-case kswapd when watermarks are boosted -- kswapd avoids reclaiming slab as reclaiming slab does not directly help compaction. As Dave notes, this decision means that slab can be artificially protected for long periods of time and messes up the balance with slab and page caches. Removing the special casing can still indirectly help avoid fragmentation by avoiding fragmentation-causing events due to slab allocation as pages from a slab pageblock will have some slab objects freed. Furthermore, with the special casing, reclaim behaviour is unpredictable as kswapd sometimes examines slab and sometimes does not in a manner that is tricky to tune or analyse. This patch removes the special casing. The downside is that this is not a universal performance win. Some benchmarks that depend on the residency of data when rereading metadata may see a regression when slab reclaim is restored to its original behaviour. Similarly, some benchmarks that only read-once or write-once may perform better when page reclaim is too aggressive. The primary upside is that slab shrinker is less surprising (arguably more sane but that's a matter of opinion), behaves consistently regardless of the fragmentation state of the system and properly obeys VM sysctls. A fsmark benchmark configuration was constructed similar to what Dave reported and is codified by the mmtest configuration config-io-fsmark-small-file-stream. It was evaluated on a 1-socket machine to avoid dealing with NUMA-related issues and the timing of reclaim. The storage was an SSD Samsung Evo and a fresh trimmed XFS filesystem was used for the test data. This is not an exact replication of Dave's setup. The configuration scales its parameters depending on the memory size of the SUT to behave similarly across machines. The parameters mean the first sample reported by fs_mark is using 50% of RAM which will barely be throttled and look like a big outlier. Dave used fake NUMA to have multiple kswapd instances which I didn't replicate. Finally, the number of iterations differ from Dave's test as the target disk was not large enough. While not identical, it should be representative. fsmark 5.3.0-rc3 5.3.0-rc3 vanilla shrinker-v1r1 Min 1-files/sec 4444.80 ( 0.00%) 4765.60 ( 7.22%) 1st-qrtle 1-files/sec 5005.10 ( 0.00%) 5091.70 ( 1.73%) 2nd-qrtle 1-files/sec 4917.80 ( 0.00%) 4855.60 ( -1.26%) 3rd-qrtle 1-files/sec 4667.40 ( 0.00%) 4831.20 ( 3.51%) Max-1 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%) Max-5 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%) Max-10 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%) Max-90 1-files/sec 4649.60 ( 0.00%) 4780.70 ( 2.82%) Max-95 1-files/sec 4491.00 ( 0.00%) 4768.20 ( 6.17%) Max-99 1-files/sec 4491.00 ( 0.00%) 4768.20 ( 6.17%) Max 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%) Hmean 1-files/sec 5004.75 ( 0.00%) 5075.96 ( 1.42%) Stddev 1-files/sec 1778.70 ( 0.00%) 1369.66 ( 23.00%) CoeffVar 1-files/sec 33.70 ( 0.00%) 26.05 ( 22.71%) BHmean-99 1-files/sec 5053.72 ( 0.00%) 5101.52 ( 0.95%) BHmean-95 1-files/sec 5053.72 ( 0.00%) 5101.52 ( 0.95%) BHmean-90 1-files/sec 5107.05 ( 0.00%) 5131.41 ( 0.48%) BHmean-75 1-files/sec 5208.45 ( 0.00%) 5206.68 ( -0.03%) BHmean-50 1-files/sec 5405.53 ( 0.00%) 5381.62 ( -0.44%) BHmean-25 1-files/sec 6179.75 ( 0.00%) 6095.14 ( -1.37%) 5.3.0-rc3 5.3.0-rc3 vanillashrinker-v1r1 Duration User 501.82 497.29 Duration System 4401.44 4424.08 Duration Elapsed 8124.76 8358.05 This is showing a slight skew for the max result representing a large outlier for the 1st, 2nd and 3rd quartile are similar indicating that the bulk of the results show little difference. Note that an earlier version of the fsmark configuration showed a regression but that included more samples taken while memory was still filling. Note that the elapsed time is higher. Part of this is that the configuration included time to delete all the test files when the test completes -- the test automation handles the possibility of testing fsmark with multiple thread counts. Without the patch, many of these objects would be memory resident which is part of what the patch is addressing. There are other important observations that justify the patch. 1. With the vanilla kernel, the number of dirty pages in the system is very low for much of the test. With this patch, dirty pages is generally kept at 10% which matches vm.dirty_background_ratio which is normal expected historical behaviour. 2. With the vanilla kernel, the ratio of Slab/Pagecache is close to 0.95 for much of the test i.e. Slab is being left alone and dominating memory consumption. With the patch applied, the ratio varies between 0.35 and 0.45 with the bulk of the measured ratios roughly half way between those values. This is a different balance to what Dave reported but it was at least consistent. 3. Slabs are scanned throughout the entire test with the patch applied. The vanille kernel has periods with no scan activity and then relatively massive spikes. 4. Without the patch, kswapd scan rates are very variable. With the patch, the scan rates remain quite steady. 4. Overall vmstats are closer to normal expectations 5.3.0-rc3 5.3.0-rc3 vanilla shrinker-v1r1 Ops Direct pages scanned 99388.00 328410.00 Ops Kswapd pages scanned 45382917.00 33451026.00 Ops Kswapd pages reclaimed 30869570.00 25239655.00 Ops Direct pages reclaimed 74131.00 5830.00 Ops Kswapd efficiency % 68.02 75.45 Ops Kswapd velocity 5585.75 4002.25 Ops Page reclaim immediate 1179721.00 430927.00 Ops Slabs scanned 62367361.00 73581394.00 Ops Direct inode steals 2103.00 1002.00 Ops Kswapd inode steals 570180.00 5183206.00 o Vanilla kernel is hitting direct reclaim more frequently, not very much in absolute terms but the fact the patch reduces it is interesting o "Page reclaim immediate" in the vanilla kernel indicates dirty pages are being encountered at the tail of the LRU. This is generally bad and means in this case that the LRU is not long enough for dirty pages to be cleaned by the background flush in time. This is much reduced by the patch. o With the patch, kswapd is reclaiming 10 times more slab pages than with the vanilla kernel. This is indicative of the watermark boosting over-protecting slab A more complete set of tests were run that were part of the basis for introducing boosting and while there are some differences, they are well within tolerances. Bottom line, the special casing kswapd to avoid slab behaviour is unpredictable and can lead to abnormal results for normal workloads. This patch restores the expected behaviour that slab and page cache is balanced consistently for a workload with a steady allocation ratio of slab/pagecache pages. It also means that if there are workloads that favour the preservation of slab over pagecache that it can be tuned via vm.vfs_cache_pressure where as the vanilla kernel effectively ignores the parameter when boosting is active. Link: http://lkml.kernel.org/r/20190808182946.GM2739@techsingularity.net Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Dave Chinner <dchinner@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> [5.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fa1e512f |
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02-Aug-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken. It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter. Add mem_cgroup_disabled() check to make reclaimer work as expected. Link: http://lkml.kernel.org/r/1563385526-20805-1-git-send-email-yang.shi@linux.alibaba.com Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reported-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jan Hadrava <had@kam.mff.cuni.cz> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <guro@fb.com> Cc: Hugh Dickins <hughd@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [4.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1732d2b01 |
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16-Jul-2019 |
Andrew Morton <akpm@linux-foundation.org> |
mm/vmscan.c: add checks for incorrect handling of current->reclaim_state Six sites are presently altering current->reclaim_state. There is a risk that one function stomps on a caller's value. Use a helper function to catch such errors. Cc: Yafang Shao <laoar.shao@gmail.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0308f7cf |
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16-Jul-2019 |
Yafang Shao <laoar.shao@gmail.com> |
mm/vmscan.c: calculate reclaimed slab caches in all reclaim paths There are six different reclaim paths by now: - kswapd reclaim path - node reclaim path - hibernate preallocate memory reclaim path - direct reclaim path - memcg reclaim path - memcg softlimit reclaim path The slab caches reclaimed in these paths are only calculated in the above three paths. There're some drawbacks if we don't calculate the reclaimed slab caches. - The sc->nr_reclaimed isn't correct if there're some slab caches relcaimed in this path. - The slab caches may be reclaimed thoroughly if there're lots of reclaimable slab caches and few page caches. Let's take an easy example for this case. If one memcg is full of slab caches and the limit of it is 512M, in other words there're approximately 512M slab caches in this memcg. Then the limit of the memcg is reached and the memcg reclaim begins, and then in this memcg reclaim path it will continuesly reclaim the slab caches until the sc->priority drops to 0. After this reclaim stops, you will find there're few slab caches left, which is less than 20M in my test case. While after this patch applied the number is greater than 300M and the sc->priority only drops to 3. Link: http://lkml.kernel.org/r/1561112086-6169-3-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e5ca8071 |
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16-Jul-2019 |
Yafang Shao <laoar.shao@gmail.com> |
mm/vmscan.c: add a new member reclaim_state in struct shrink_control Patch series "mm/vmscan: calculate reclaimed slab in all reclaim paths". This patchset is to fix the issues in doing shrink slab. There're six different reclaim paths by now, - kswapd reclaim path - node reclaim path - hibernate preallocate memory reclaim path - direct reclaim path - memcg reclaim path - memcg softlimit reclaim path The slab caches reclaimed in these paths are only calculated in the above three paths. The issues are detailed explained in patch #2. We should calculate the reclaimed slab caches in every reclaim path. In order to do it, the struct reclaim_state is placed into the struct shrink_control. In node reclaim path, there'is another issue about shrinking slab, which is adressed in "mm/vmscan: shrink slab in node reclaim" (https://lore.kernel.org/linux-mm/1559874946-22960-1-git-send-email-laoar.shao@gmail.com/). This patch (of 2): The struct reclaim_state is used to record how many slab caches are reclaimed in one reclaim path. The struct shrink_control is used to control one reclaim path. So we'd better put reclaim_state into shrink_control. [laoar.shao@gmail.com: remove reclaim_state assignment from __perform_reclaim()] Link: http://lkml.kernel.org/r/1561381582-13697-1-git-send-email-laoar.shao@gmail.com Link: http://lkml.kernel.org/r/1561112086-6169-2-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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98879b3b |
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11-Jul-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: vmscan: correct some vmscan counters for THP swapout Commit bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped out"), THP can be swapped out in a whole. But, nr_reclaimed and some other vm counters still get inc'ed by one even though a whole THP (512 pages) gets swapped out. This doesn't make too much sense to memory reclaim. For example, direct reclaim may just need reclaim SWAP_CLUSTER_MAX pages, reclaiming one THP could fulfill it. But, if nr_reclaimed is not increased correctly, direct reclaim may just waste time to reclaim more pages, SWAP_CLUSTER_MAX * 512 pages in worst case. And, it may cause pgsteal_{kswapd|direct} is greater than pgscan_{kswapd|direct}, like the below: pgsteal_kswapd 122933 pgsteal_direct 26600225 pgscan_kswapd 174153 pgscan_direct 14678312 nr_reclaimed and nr_scanned must be fixed in parallel otherwise it would break some page reclaim logic, e.g. vmpressure: this looks at the scanned/reclaimed ratio so it won't change semantics as long as scanned & reclaimed are fixed in parallel. compaction/reclaim: compaction wants a certain number of physical pages freed up before going back to compacting. kswapd priority raising: kswapd raises priority if we scan fewer pages than the reclaim target (which itself is obviously expressed in order-0 pages). As a result, kswapd can falsely raise its aggressiveness even when it's making great progress. Other than nr_scanned and nr_reclaimed, some other counters, e.g. pgactivate, nr_skipped, nr_ref_keep and nr_unmap_fail need to be fixed too since they are user visible via cgroup, /proc/vmstat or trace points, otherwise they would be underreported. When isolating pages from LRUs, nr_taken has been accounted in base page, but nr_scanned and nr_skipped are still accounted in THP. It doesn't make too much sense too since this may cause trace point underreport the numbers as well. So accounting those counters in base page instead of accounting THP as one page. nr_dirty, nr_unqueued_dirty, nr_congested and nr_writeback are used by file cache, so they are not impacted by THP swap. This change may result in lower steal/scan ratio in some cases since THP may get split during page reclaim, then a part of tail pages get reclaimed instead of the whole 512 pages, but nr_scanned is accounted by 512, particularly for direct reclaim. But, this should be not a significant issue. Link: http://lkml.kernel.org/r/1559025859-72759-2-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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af5d4403 |
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11-Jul-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: vmscan: remove double slab pressure by inc'ing sc->nr_scanned Commit 9092c71bb724 ("mm: use sc->priority for slab shrink targets") has broken up the relationship between sc->nr_scanned and slab pressure. The sc->nr_scanned can't double slab pressure anymore. So, it sounds no sense to still keep sc->nr_scanned inc'ed. Actually, it would prevent from adding pressure on slab shrink since excessive sc->nr_scanned would prevent from scan->priority raise. The bonnie test doesn't show this would change the behavior of slab shrinkers. w/ w/o /sec %CP /sec %CP Sequential delete: 3960.6 94.6 3997.6 96.2 Random delete: 2518 63.8 2561.6 64.6 The slight increase of "/sec" without the patch would be caused by the slight increase of CPU usage. Link: http://lkml.kernel.org/r/1559025859-72759-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2c012a4a |
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11-Jul-2019 |
Kuo-Hsin Yang <vovoy@chromium.org> |
mm: vmscan: scan anonymous pages on file refaults When file refaults are detected and there are many inactive file pages, the system never reclaim anonymous pages, the file pages are dropped aggressively when there are still a lot of cold anonymous pages and system thrashes. This issue impacts the performance of applications with large executable, e.g. chrome. With this patch, when file refault is detected, inactive_list_is_low() always returns true for file pages in get_scan_count() to enable scanning anonymous pages. The problem can be reproduced by the following test program. ---8<--- void fallocate_file(const char *filename, off_t size) { struct stat st; int fd; if (!stat(filename, &st) && st.st_size >= size) return; fd = open(filename, O_WRONLY | O_CREAT, 0600); if (fd < 0) { perror("create file"); exit(1); } if (posix_fallocate(fd, 0, size)) { perror("fallocate"); exit(1); } close(fd); } long *alloc_anon(long size) { long *start = malloc(size); memset(start, 1, size); return start; } long access_file(const char *filename, long size, long rounds) { int fd, i; volatile char *start1, *end1, *start2; const int page_size = getpagesize(); long sum = 0; fd = open(filename, O_RDONLY); if (fd == -1) { perror("open"); exit(1); } /* * Some applications, e.g. chrome, use a lot of executable file * pages, map some of the pages with PROT_EXEC flag to simulate * the behavior. */ start1 = mmap(NULL, size / 2, PROT_READ | PROT_EXEC, MAP_SHARED, fd, 0); if (start1 == MAP_FAILED) { perror("mmap"); exit(1); } end1 = start1 + size / 2; start2 = mmap(NULL, size / 2, PROT_READ, MAP_SHARED, fd, size / 2); if (start2 == MAP_FAILED) { perror("mmap"); exit(1); } for (i = 0; i < rounds; ++i) { struct timeval before, after; volatile char *ptr1 = start1, *ptr2 = start2; gettimeofday(&before, NULL); for (; ptr1 < end1; ptr1 += page_size, ptr2 += page_size) sum += *ptr1 + *ptr2; gettimeofday(&after, NULL); printf("File access time, round %d: %f (sec) ", i, (after.tv_sec - before.tv_sec) + (after.tv_usec - before.tv_usec) / 1000000.0); } return sum; } int main(int argc, char *argv[]) { const long MB = 1024 * 1024; long anon_mb, file_mb, file_rounds; const char filename[] = "large"; long *ret1; long ret2; if (argc != 4) { printf("usage: thrash ANON_MB FILE_MB FILE_ROUNDS "); exit(0); } anon_mb = atoi(argv[1]); file_mb = atoi(argv[2]); file_rounds = atoi(argv[3]); fallocate_file(filename, file_mb * MB); printf("Allocate %ld MB anonymous pages ", anon_mb); ret1 = alloc_anon(anon_mb * MB); printf("Access %ld MB file pages ", file_mb); ret2 = access_file(filename, file_mb * MB, file_rounds); printf("Print result to prevent optimization: %ld ", *ret1 + ret2); return 0; } ---8<--- Running the test program on 2GB RAM VM with kernel 5.2.0-rc5, the program fills ram with 2048 MB memory, access a 200 MB file for 10 times. Without this patch, the file cache is dropped aggresively and every access to the file is from disk. $ ./thrash 2048 200 10 Allocate 2048 MB anonymous pages Access 200 MB file pages File access time, round 0: 2.489316 (sec) File access time, round 1: 2.581277 (sec) File access time, round 2: 2.487624 (sec) File access time, round 3: 2.449100 (sec) File access time, round 4: 2.420423 (sec) File access time, round 5: 2.343411 (sec) File access time, round 6: 2.454833 (sec) File access time, round 7: 2.483398 (sec) File access time, round 8: 2.572701 (sec) File access time, round 9: 2.493014 (sec) With this patch, these file pages can be cached. $ ./thrash 2048 200 10 Allocate 2048 MB anonymous pages Access 200 MB file pages File access time, round 0: 2.475189 (sec) File access time, round 1: 2.440777 (sec) File access time, round 2: 2.411671 (sec) File access time, round 3: 1.955267 (sec) File access time, round 4: 0.029924 (sec) File access time, round 5: 0.000808 (sec) File access time, round 6: 0.000771 (sec) File access time, round 7: 0.000746 (sec) File access time, round 8: 0.000738 (sec) File access time, round 9: 0.000747 (sec) Checked the swap out stats during the test [1], 19006 pages swapped out with this patch, 3418 pages swapped out without this patch. There are more swap out, but I think it's within reasonable range when file backed data set doesn't fit into the memory. $ ./thrash 2000 100 2100 5 1 # ANON_MB FILE_EXEC FILE_NOEXEC ROUNDS PROCESSES Allocate 2000 MB anonymous pages active_anon: 1613644, inactive_anon: 348656, active_file: 892, inactive_file: 1384 (kB) pswpout: 7972443, pgpgin: 478615246 Access 100 MB executable file pages Access 2100 MB regular file pages File access time, round 0: 12.165, (sec) active_anon: 1433788, inactive_anon: 478116, active_file: 17896, inactive_file: 24328 (kB) File access time, round 1: 11.493, (sec) active_anon: 1430576, inactive_anon: 477144, active_file: 25440, inactive_file: 26172 (kB) File access time, round 2: 11.455, (sec) active_anon: 1427436, inactive_anon: 476060, active_file: 21112, inactive_file: 28808 (kB) File access time, round 3: 11.454, (sec) active_anon: 1420444, inactive_anon: 473632, active_file: 23216, inactive_file: 35036 (kB) File access time, round 4: 11.479, (sec) active_anon: 1413964, inactive_anon: 471460, active_file: 31728, inactive_file: 32224 (kB) pswpout: 7991449 (+ 19006), pgpgin: 489924366 (+ 11309120) With 4 processes accessing non-overlapping parts of a large file, 30316 pages swapped out with this patch, 5152 pages swapped out without this patch. The swapout number is small comparing to pgpgin. [1]: https://github.com/vovo/testing/blob/master/mem_thrash.c Link: http://lkml.kernel.org/r/20190701081038.GA83398@google.com Fixes: e9868505987a ("mm,vmscan: only evict file pages when we have plenty") Fixes: 7c5bd705d8f9 ("mm: memcg: only evict file pages when we have plenty") Signed-off-by: Kuo-Hsin Yang <vovoy@chromium.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Sonny Rao <sonnyrao@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Rik van Riel <riel@redhat.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dffcac2c |
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04-Jul-2019 |
Shakeel Butt <shakeelb@google.com> |
mm/vmscan.c: prevent useless kswapd loops In production we have noticed hard lockups on large machines running large jobs due to kswaps hoarding lru lock within isolate_lru_pages when sc->reclaim_idx is 0 which is a small zone. The lru was couple hundred GiBs and the condition (page_zonenum(page) > sc->reclaim_idx) in isolate_lru_pages() was basically skipping GiBs of pages while holding the LRU spinlock with interrupt disabled. On further inspection, it seems like there are two issues: (1) If kswapd on the return from balance_pgdat() could not sleep (i.e. node is still unbalanced), the classzone_idx is unintentionally set to 0 and the whole reclaim cycle of kswapd will try to reclaim only the lowest and smallest zone while traversing the whole memory. (2) Fundamentally isolate_lru_pages() is really bad when the allocation has woken kswapd for a smaller zone on a very large machine running very large jobs. It can hoard the LRU spinlock while skipping over 100s of GiBs of pages. This patch only fixes (1). (2) needs a more fundamental solution. To fix (1), in the kswapd context, if pgdat->kswapd_classzone_idx is invalid use the classzone_idx of the previous kswapd loop otherwise use the one the waker has requested. Link: http://lkml.kernel.org/r/20190701201847.251028-1-shakeelb@google.com Fixes: e716f2eb24de ("mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx") Signed-off-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hdanton@sina.com> Cc: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a58f2cef |
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13-Jun-2019 |
Minchan Kim <minchan@kernel.org> |
mm/vmscan.c: fix trying to reclaim unevictable LRU page There was the below bug report from Wu Fangsuo. On the CMA allocation path, isolate_migratepages_range() could isolate unevictable LRU pages and reclaim_clean_page_from_list() can try to reclaim them if they are clean file-backed pages. page:ffffffbf02f33b40 count:86 mapcount:84 mapping:ffffffc08fa7a810 index:0x24 flags: 0x19040c(referenced|uptodate|arch_1|mappedtodisk|unevictable|mlocked) raw: 000000000019040c ffffffc08fa7a810 0000000000000024 0000005600000053 raw: ffffffc009b05b20 ffffffc009b05b20 0000000000000000 ffffffc09bf3ee80 page dumped because: VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page)) page->mem_cgroup:ffffffc09bf3ee80 ------------[ cut here ]------------ kernel BUG at /home/build/farmland/adroid9.0/kernel/linux/mm/vmscan.c:1350! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 7125 Comm: syz-executor Tainted: G S 4.14.81 #3 Hardware name: ASR AQUILAC EVB (DT) task: ffffffc00a54cd00 task.stack: ffffffc009b00000 PC is at shrink_page_list+0x1998/0x3240 LR is at shrink_page_list+0x1998/0x3240 pc : [<ffffff90083a2158>] lr : [<ffffff90083a2158>] pstate: 60400045 sp : ffffffc009b05940 .. shrink_page_list+0x1998/0x3240 reclaim_clean_pages_from_list+0x3c0/0x4f0 alloc_contig_range+0x3bc/0x650 cma_alloc+0x214/0x668 ion_cma_allocate+0x98/0x1d8 ion_alloc+0x200/0x7e0 ion_ioctl+0x18c/0x378 do_vfs_ioctl+0x17c/0x1780 SyS_ioctl+0xac/0xc0 Wu found it's due to commit ad6b67041a45 ("mm: remove SWAP_MLOCK in ttu"). Before that, unevictable pages go to cull_mlocked so that we can't reach the VM_BUG_ON_PAGE line. To fix the issue, this patch filters out unevictable LRU pages from the reclaim_clean_pages_from_list in CMA. Link: http://lkml.kernel.org/r/20190524071114.74202-1-minchan@kernel.org Fixes: ad6b67041a45 ("mm: remove SWAP_MLOCK in ttu") Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Wu Fangsuo <fangsuowu@asrmicro.com> Debugged-by: Wu Fangsuo <fangsuowu@asrmicro.com> Tested-by: Wu Fangsuo <fangsuowu@asrmicro.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Pankaj Suryawanshi <pankaj.suryawanshi@einfochips.com> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b17f18af |
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13-Jun-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: fix recent_rotated history Johannes pointed out that after commit 886cf1901db9 ("mm: move recent_rotated pages calculation to shrink_inactive_list()") we lost all zone_reclaim_stat::recent_rotated history. This fixes it. Link: http://lkml.kernel.org/r/155905972210.26456.11178359431724024112.stgit@localhost.localdomain Fixes: 886cf1901db9 ("mm: move recent_rotated pages calculation to shrink_inactive_list()") Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reported-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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205b20cc |
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14-May-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: make cgroup stats and events query API explicitly local Patch series "mm: memcontrol: memory.stat cost & correctness". The cgroup memory.stat file holds recursive statistics for the entire subtree. The current implementation does this tree walk on-demand whenever the file is read. This is giving us problems in production. 1. The cost of aggregating the statistics on-demand is high. A lot of system service cgroups are mostly idle and their stats don't change between reads, yet we always have to check them. There are also always some lazily-dying cgroups sitting around that are pinned by a handful of remaining page cache; the same applies to them. In an application that periodically monitors memory.stat in our fleet, we have seen the aggregation consume up to 5% CPU time. 2. When cgroups die and disappear from the cgroup tree, so do their accumulated vm events. The result is that the event counters at higher-level cgroups can go backwards and confuse some of our automation, let alone people looking at the graphs over time. To address both issues, this patch series changes the stat implementation to spill counts upwards when the counters change. The upward spilling is batched using the existing per-cpu cache. In a sparse file stress test with 5 level cgroup nesting, the additional cost of the flushing was negligible (a little under 1% of CPU at 100% CPU utilization, compared to the 5% of reading memory.stat during regular operation). This patch (of 4): memcg_page_state(), lruvec_page_state(), memcg_sum_events() are currently returning the state of the local memcg or lruvec, not the recursive state. In practice there is a demand for both versions, although the callers that want the recursive counts currently sum them up by hand. Per default, cgroups are considered recursive entities and generally we expect more users of the recursive counters, with the local counts being special cases. To reflect that in the name, add a _local suffix to the current implementations. The following patch will re-incarnate these functions with recursive semantics, but with an O(1) implementation. [hannes@cmpxchg.org: fix bisection hole] Link: http://lkml.kernel.org/r/20190417160347.GC23013@cmpxchg.org Link: http://lkml.kernel.org/r/20190412151507.2769-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2fa2690c |
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13-May-2019 |
Yafang Shao <laoar.shao@gmail.com> |
mm/vmscan.c: don't disable irq again when count pgrefill for memcg We can use __count_memcg_events() directly because this callsite is alreay protected by spin_lock_irq(). Link: http://lkml.kernel.org/r/1556093494-30798-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f46b7912 |
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13-May-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: simplify shrink_inactive_list() This merges together duplicated patterns of code. Also, replace count_memcg_events() with its irq-careless namesake, because they are already called in interrupts disabled context. Link: http://lkml.kernel.org/r/2ece1df4-2989-bc9b-6172-61e9fdde5bfd@virtuozzo.com Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Baoquan He <bhe@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3481c37f |
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13-May-2019 |
Yafang Shao <laoar.shao@gmail.com> |
mm/vmscan: drop may_writepage and classzone_idx from direct reclaim begin template There are three tracepoints using this template, which are mm_vmscan_direct_reclaim_begin, mm_vmscan_memcg_reclaim_begin, mm_vmscan_memcg_softlimit_reclaim_begin. Regarding mm_vmscan_direct_reclaim_begin, sc.may_writepage is !laptop_mode, that's a static setting, and reclaim_idx is derived from gfp_mask which is already show in this tracepoint. Regarding mm_vmscan_memcg_reclaim_begin, may_writepage is !laptop_mode too, and reclaim_idx is (MAX_NR_ZONES-1), which are both static value. mm_vmscan_memcg_softlimit_reclaim_begin is the same with mm_vmscan_memcg_reclaim_begin. So we can drop them all. Link: http://lkml.kernel.org/r/1553736322-32235-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1a61ab80 |
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13-May-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: replace zone summing with lruvec_page_state() Instead of adding up the zone counters, use lruvec_page_state() to get the node state directly. This is a bit cheaper and more stream-lined. Link: http://lkml.kernel.org/r/20190228163020.24100-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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132bb8cf |
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13-May-2019 |
Yafang Shao <laoar.shao@gmail.com> |
mm/vmscan: add tracepoints for node reclaim The page alloc fast path it may perform node reclaim, which may cause a latency spike. We should add tracepoint for this event, and also measure the latency it causes. So bellow two tracepoints are introduced, mm_vmscan_node_reclaim_begin mm_vmscan_node_reclaim_end Link: http://lkml.kernel.org/r/1551421452-5385-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: <shaoyafang@didiglobal.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a222f341 |
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13-May-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: generalize putback scan functions This combines two similar functions move_active_pages_to_lru() and putback_inactive_pages() into single move_pages_to_lru(). This remove duplicate code and makes object file size smaller. Before: text data bss dec hex filename 57082 4732 128 61942 f1f6 mm/vmscan.o After: text data bss dec hex filename 55112 4600 128 59840 e9c0 mm/vmscan.o Note, that now we are checking for !page_evictable() coming from shrink_active_list(), which shouldn't change any behavior since that path works with evictable pages only. Link: http://lkml.kernel.org/r/155290129627.31489.8321971028677203248.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f372d89e |
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13-May-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: remove pages_to_free argument of move_active_pages_to_lru() We may use input argument list as output argument too. This makes the function more similar to putback_inactive_pages(). Link: http://lkml.kernel.org/r/155290129079.31489.16180612694090502942.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9851ac13 |
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13-May-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: move nr_deactivate accounting to shrink_active_list() We know which LRU is not active. [chris@chrisdown.name: fix build on !CONFIG_MEMCG] Link: http://lkml.kernel.org/r/20190322150513.GA22021@chrisdown.name Link: http://lkml.kernel.org/r/155290128498.31489.18250485448913338607.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Chris Down <chris@chrisdown.name> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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886cf190 |
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13-May-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: move recent_rotated pages calculation to shrink_inactive_list() Patch series "mm: Generalize putback functions"] putback_inactive_pages() and move_active_pages_to_lru() are almost similar, so this patchset merges them ina single function. This patch (of 4): The patch moves the calculation from putback_inactive_pages() to shrink_inactive_list(). This makes putback_inactive_pages() looking more similar to move_active_pages_to_lru(). To do that, we account activated pages in reclaim_stat::nr_activate. Since a page may change its LRU type from anon to file cache inside shrink_page_list() (see ClearPageSwapBacked()), we have to account pages for the both types. So, nr_activate becomes an array. Previously we used nr_activate to account PGACTIVATE events, but now we account them into pgactivate variable (since they are about number of pages in general, not about sum of hpage_nr_pages). Link: http://lkml.kernel.org/r/155290127956.31489.3393586616054413298.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3b991208 |
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18-Apr-2019 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: fix inactive list balancing between NUMA nodes and cgroups During !CONFIG_CGROUP reclaim, we expand the inactive list size if it's thrashing on the node that is about to be reclaimed. But when cgroups are enabled, we suddenly ignore the node scope and use the cgroup scope only. The result is that pressure bleeds between NUMA nodes depending on whether cgroups are merely compiled into Linux. This behavioral difference is unexpected and undesirable. When the refault adaptivity of the inactive list was first introduced, there were no statistics at the lruvec level - the intersection of node and memcg - so it was better than nothing. But now that we have that infrastructure, use lruvec_page_state() to make the list balancing decision always NUMA aware. [hannes@cmpxchg.org: fix bisection hole] Link: http://lkml.kernel.org/r/20190417155241.GB23013@cmpxchg.org Link: http://lkml.kernel.org/r/20190412144438.2645-1-hannes@cmpxchg.org Fixes: 2a2e48854d70 ("mm: vmscan: fix IO/refault regression in cache workingset transition") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d75f773c |
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25-Mar-2019 |
Sakari Ailus <sakari.ailus@linux.intel.com> |
treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively %pF and %pf are functionally equivalent to %pS and %ps conversion specifiers. The former are deprecated, therefore switch the current users to use the preferred variant. The changes have been produced by the following command: git grep -l '%p[fF]' | grep -v '^\(tools\|Documentation\)/' | \ while read i; do perl -i -pe 's/%pf/%ps/g; s/%pF/%pS/g;' $i; done And verifying the result. Link: http://lkml.kernel.org/r/20190325193229.23390-1-sakari.ailus@linux.intel.com Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: linux-arm-kernel@lists.infradead.org Cc: sparclinux@vger.kernel.org Cc: linux-um@lists.infradead.org Cc: xen-devel@lists.xenproject.org Cc: linux-acpi@vger.kernel.org Cc: linux-pm@vger.kernel.org Cc: drbd-dev@lists.linbit.com Cc: linux-block@vger.kernel.org Cc: linux-mmc@vger.kernel.org Cc: linux-nvdimm@lists.01.org Cc: linux-pci@vger.kernel.org Cc: linux-scsi@vger.kernel.org Cc: linux-btrfs@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: linux-mm@kvack.org Cc: ceph-devel@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Acked-by: David Sterba <dsterba@suse.com> (for btrfs) Acked-by: Mike Rapoport <rppt@linux.ibm.com> (for mm/memblock.c) Acked-by: Bjorn Helgaas <bhelgaas@google.com> (for drivers/pci) Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
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#
f4b7e272 |
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05-Mar-2019 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm: remove zone_lru_lock() function, access ->lru_lock directly We have common pattern to access lru_lock from a page pointer: zone_lru_lock(page_zone(page)) Which is silly, because it unfolds to this: &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock while we can simply do &NODE_DATA(page_to_nid(page))->lru_lock Remove zone_lru_lock() function, since it's only complicate things. Use 'page_pgdat(page)->lru_lock' pattern instead. [aryabinin@virtuozzo.com: a slightly better version of __split_huge_page()] Link: http://lkml.kernel.org/r/20190301121651.7741-1-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20190228083329.31892-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a7ca12f9 |
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05-Mar-2019 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/workingset: remove unused @mapping argument in workingset_eviction() workingset_eviction() doesn't use and never did use the @mapping argument. Remove it. Link: http://lkml.kernel.org/r/20190228083329.31892-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@surriel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b9726c26 |
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05-Mar-2019 |
Alexey Dobriyan <adobriyan@gmail.com> |
numa: make "nr_node_ids" unsigned int Number of NUMA nodes can't be negative. This saves a few bytes on x86_64: add/remove: 0/0 grow/shrink: 4/21 up/down: 27/-265 (-238) Function old new delta hv_synic_alloc.cold 88 110 +22 prealloc_shrinker 260 262 +2 bootstrap 249 251 +2 sched_init_numa 1566 1567 +1 show_slab_objects 778 777 -1 s_show 1201 1200 -1 kmem_cache_init 346 345 -1 __alloc_workqueue_key 1146 1145 -1 mem_cgroup_css_alloc 1614 1612 -2 __do_sys_swapon 4702 4699 -3 __list_lru_init 655 651 -4 nic_probe 2379 2374 -5 store_user_store 118 111 -7 red_zone_store 106 99 -7 poison_store 106 99 -7 wq_numa_init 348 338 -10 __kmem_cache_empty 75 65 -10 task_numa_free 186 173 -13 merge_across_nodes_store 351 336 -15 irq_create_affinity_masks 1261 1246 -15 do_numa_crng_init 343 321 -22 task_numa_fault 4760 4737 -23 swapfile_init 179 156 -23 hv_synic_alloc 536 492 -44 apply_wqattrs_prepare 746 695 -51 Link: http://lkml.kernel.org/r/20190201223029.GA15820@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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060f005f |
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05-Mar-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: do not allocate duplicate stack variables in shrink_page_list() On path shrink_inactive_list() ---> shrink_page_list() we allocate stack variables for the statistics twice. This is completely useless, and this just consumes stack much more, then we really need. The patch kills duplicate stack variables from shrink_page_list(), and this reduce stack usage and object file size significantly: Stack usage: Before: vmscan.c:1122:22:shrink_page_list 648 static After: vmscan.c:1122:22:shrink_page_list 616 static Size of vmscan.o: text data bss dec hex filename Before: 56866 4720 128 61714 f112 mm/vmscan.o After: 56770 4720 128 61618 f0b2 mm/vmscan.o Link: http://lkml.kernel.org/r/154894900030.5211.12104993874109647641.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2bb0f34f |
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05-Mar-2019 |
Yang Shi <yang.shi@linux.alibaba.com> |
mm: vmscan: do not iterate all mem cgroups for global direct reclaim In current implementation, both kswapd and direct reclaim has to iterate all mem cgroups. It is not a problem before offline mem cgroups could be iterated. But, currently with iterating offline mem cgroups, it could be very time consuming. In our workloads, we saw over 400K mem cgroups accumulated in some cases, only a few hundred are online memcgs. Although kswapd could help out to reduce the number of memcgs, direct reclaim still get hit with iterating a number of offline memcgs in some cases. We experienced the responsiveness problems due to this occassionally. A simple test with pref shows it may take around 220ms to iterate 8K memcgs in direct reclaim: dd 13873 [011] 578.542919: vmscan:mm_vmscan_direct_reclaim_begin dd 13873 [011] 578.758689: vmscan:mm_vmscan_direct_reclaim_end So for 400K, it may take around 11 seconds to iterate all memcgs. Here just break the iteration once it reclaims enough pages as what memcg direct reclaim does. This may hurt the fairness among memcgs. But the cached iterator cookie could help to achieve the fairness more or less. Link: http://lkml.kernel.org/r/1548799877-10949-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a9e7c39f |
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05-Mar-2019 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: remove 7th argument of isolate_lru_pages() We may simply check for sc->may_unmap in isolate_lru_pages() instead of doing that in both of its callers. Link: http://lkml.kernel.org/r/154748280735.29962.15867846875217618569.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8bb4e7a2 |
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05-Mar-2019 |
Wei Yang <richard.weiyang@gmail.com> |
mm: fix some typos in mm directory No functional change. Link: http://lkml.kernel.org/r/20190118235123.27843-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a9a238e8 |
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12-Feb-2019 |
Dave Chinner <dchinner@redhat.com> |
Revert "mm: slowly shrink slabs with a relatively small number of objects" This reverts commit 172b06c32b9497 ("mm: slowly shrink slabs with a relatively small number of objects"). This change changes the agressiveness of shrinker reclaim, causing small cache and low priority reclaim to greatly increase scanning pressure on small caches. As a result, light memory pressure has a disproportionate affect on small caches, and causes large caches to be reclaimed much faster than previously. As a result, it greatly perturbs the delicate balance of the VFS caches (dentry/inode vs file page cache) such that the inode/dentry caches are reclaimed much, much faster than the page cache and this drives us into several other caching imbalance related problems. As such, this is a bad change and needs to be reverted. [ Needs some massaging to retain the later seekless shrinker modifications.] Link: http://lkml.kernel.org/r/20190130041707.27750-3-david@fromorbit.com Fixes: 172b06c32b9497 ("mm: slowly shrink slabs with a relatively small number of objects") Signed-off-by: Dave Chinner <dchinner@redhat.com> Cc: Wolfgang Walter <linux@stwm.de> Cc: Roman Gushchin <guro@fb.com> Cc: Spock <dairinin@gmail.com> Cc: Rik van Riel <riel@surriel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9a1ea439 |
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28-Dec-2018 |
Hugh Dickins <hughd@google.com> |
mm: put_and_wait_on_page_locked() while page is migrated Waiting on a page migration entry has used wait_on_page_locked() all along since 2006: but you cannot safely wait_on_page_locked() without holding a reference to the page, and that extra reference is enough to make migrate_page_move_mapping() fail with -EAGAIN, when a racing task faults on the entry before migrate_page_move_mapping() gets there. And that failure is retried nine times, amplifying the pain when trying to migrate a popular page. With a single persistent faulter, migration sometimes succeeds; with two or three concurrent faulters, success becomes much less likely (and the more the page was mapped, the worse the overhead of unmapping and remapping it on each try). This is especially a problem for memory offlining, where the outer level retries forever (or until terminated from userspace), because a heavy refault workload can trigger an endless loop of migration failures. wait_on_page_locked() is the wrong tool for the job. David Herrmann (but was he the first?) noticed this issue in 2014: https://marc.info/?l=linux-mm&m=140110465608116&w=2 Tim Chen started a thread in August 2017 which appears relevant: https://marc.info/?l=linux-mm&m=150275941014915&w=2 where Kan Liang went on to implicate __migration_entry_wait(): https://marc.info/?l=linux-mm&m=150300268411980&w=2 and the thread ended up with the v4.14 commits: 2554db916586 ("sched/wait: Break up long wake list walk") 11a19c7b099f ("sched/wait: Introduce wakeup boomark in wake_up_page_bit") Baoquan He reported "Memory hotplug softlock issue" 14 November 2018: https://marc.info/?l=linux-mm&m=154217936431300&w=2 We have all assumed that it is essential to hold a page reference while waiting on a page lock: partly to guarantee that there is still a struct page when MEMORY_HOTREMOVE is configured, but also to protect against reuse of the struct page going to someone who then holds the page locked indefinitely, when the waiter can reasonably expect timely unlocking. But in fact, so long as wait_on_page_bit_common() does the put_page(), and is careful not to rely on struct page contents thereafter, there is no need to hold a reference to the page while waiting on it. That does mean that this case cannot go back through the loop: but that's fine for the page migration case, and even if used more widely, is limited by the "Stop walking if it's locked" optimization in wake_page_function(). Add interface put_and_wait_on_page_locked() to do this, using "behavior" enum in place of "lock" arg to wait_on_page_bit_common() to implement it. No interruptible or killable variant needed yet, but they might follow: I have a vague notion that reporting -EINTR should take precedence over return from wait_on_page_bit_common() without knowing the page state, so arrange it accordingly - but that may be nothing but pedantic. __migration_entry_wait() still has to take a brief reference to the page, prior to calling put_and_wait_on_page_locked(): but now that it is dropped before waiting, the chance of impeding page migration is very much reduced. Should we perhaps disable preemption across this? shrink_page_list()'s __ClearPageLocked(): that was a surprise! This survived a lot of testing before that showed up. PageWaiters may have been set by wait_on_page_bit_common(), and the reference dropped, just before shrink_page_list() succeeds in freezing its last page reference: in such a case, unlock_page() must be used. Follow the suggestion from Michal Hocko, just revert a978d6f52106 ("mm: unlockless reclaim") now: that optimization predates PageWaiters, and won't buy much these days; but we can reinstate it for the !PageWaiters case if anyone notices. It does raise the question: should vmscan.c's is_page_cache_freeable() and __remove_mapping() now treat a PageWaiters page as if an extra reference were held? Perhaps, but I don't think it matters much, since shrink_page_list() already had to win its trylock_page(), so waiters are not very common there: I noticed no difference when trying the bigger change, and it's surely not needed while put_and_wait_on_page_locked() is only used for page migration. [willy@infradead.org: add put_and_wait_on_page_locked() kerneldoc] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261121330.1116@eggly.anvils Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Baoquan He <bhe@redhat.com> Tested-by: Baoquan He <bhe@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Baoquan He <bhe@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Herrmann <dh.herrmann@gmail.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Lameter <cl@linux.com> Cc: Nick Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1c30844d |
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28-Dec-2018 |
Mel Gorman <mgorman@techsingularity.net> |
mm: reclaim small amounts of memory when an external fragmentation event occurs An external fragmentation event was previously described as When the page allocator fragments memory, it records the event using the mm_page_alloc_extfrag event. If the fallback_order is smaller than a pageblock order (order-9 on 64-bit x86) then it's considered an event that will cause external fragmentation issues in the future. The kernel reduces the probability of such events by increasing the watermark sizes by calling set_recommended_min_free_kbytes early in the lifetime of the system. This works reasonably well in general but if there are enough sparsely populated pageblocks then the problem can still occur as enough memory is free overall and kswapd stays asleep. This patch introduces a watermark_boost_factor sysctl that allows a zone watermark to be temporarily boosted when an external fragmentation causing events occurs. The boosting will stall allocations that would decrease free memory below the boosted low watermark and kswapd is woken if the calling context allows to reclaim an amount of memory relative to the size of the high watermark and the watermark_boost_factor until the boost is cleared. When kswapd finishes, it wakes kcompactd at the pageblock order to clean some of the pageblocks that may have been affected by the fragmentation event. kswapd avoids any writeback, slab shrinkage and swap from reclaim context during this operation to avoid excessive system disruption in the name of fragmentation avoidance. Care is taken so that kswapd will do normal reclaim work if the system is really low on memory. This was evaluated using the same workloads as "mm, page_alloc: Spread allocations across zones before introducing fragmentation". 1-socket Skylake machine config-global-dhp__workload_thpfioscale XFS (no special madvise) 4 fio threads, 1 THP allocating thread -------------------------------------- 4.20-rc3 extfrag events < order 9: 804694 4.20-rc3+patch: 408912 (49% reduction) 4.20-rc3+patch1-4: 18421 (98% reduction) 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Amean fault-base-1 653.58 ( 0.00%) 652.71 ( 0.13%) Amean fault-huge-1 0.00 ( 0.00%) 178.93 * -99.00%* 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Percentage huge-1 0.00 ( 0.00%) 5.12 ( 100.00%) Note that external fragmentation causing events are massively reduced by this path whether in comparison to the previous kernel or the vanilla kernel. The fault latency for huge pages appears to be increased but that is only because THP allocations were successful with the patch applied. 1-socket Skylake machine global-dhp__workload_thpfioscale-madvhugepage-xfs (MADV_HUGEPAGE) ----------------------------------------------------------------- 4.20-rc3 extfrag events < order 9: 291392 4.20-rc3+patch: 191187 (34% reduction) 4.20-rc3+patch1-4: 13464 (95% reduction) thpfioscale Fault Latencies 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Min fault-base-1 912.00 ( 0.00%) 905.00 ( 0.77%) Min fault-huge-1 127.00 ( 0.00%) 135.00 ( -6.30%) Amean fault-base-1 1467.55 ( 0.00%) 1481.67 ( -0.96%) Amean fault-huge-1 1127.11 ( 0.00%) 1063.88 * 5.61%* 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Percentage huge-1 77.64 ( 0.00%) 83.46 ( 7.49%) As before, massive reduction in external fragmentation events, some jitter on latencies and an increase in THP allocation success rates. 2-socket Haswell machine config-global-dhp__workload_thpfioscale XFS (no special madvise) 4 fio threads, 5 THP allocating threads ---------------------------------------------------------------- 4.20-rc3 extfrag events < order 9: 215698 4.20-rc3+patch: 200210 (7% reduction) 4.20-rc3+patch1-4: 14263 (93% reduction) 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Amean fault-base-5 1346.45 ( 0.00%) 1306.87 ( 2.94%) Amean fault-huge-5 3418.60 ( 0.00%) 1348.94 ( 60.54%) 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Percentage huge-5 0.78 ( 0.00%) 7.91 ( 910.64%) There is a 93% reduction in fragmentation causing events, there is a big reduction in the huge page fault latency and allocation success rate is higher. 2-socket Haswell machine global-dhp__workload_thpfioscale-madvhugepage-xfs (MADV_HUGEPAGE) ----------------------------------------------------------------- 4.20-rc3 extfrag events < order 9: 166352 4.20-rc3+patch: 147463 (11% reduction) 4.20-rc3+patch1-4: 11095 (93% reduction) thpfioscale Fault Latencies 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Amean fault-base-5 6217.43 ( 0.00%) 7419.67 * -19.34%* Amean fault-huge-5 3163.33 ( 0.00%) 3263.80 ( -3.18%) 4.20.0-rc3 4.20.0-rc3 lowzone-v5r8 boost-v5r8 Percentage huge-5 95.14 ( 0.00%) 87.98 ( -7.53%) There is a large reduction in fragmentation events with some jitter around the latencies and success rates. As before, the high THP allocation success rate does mean the system is under a lot of pressure. However, as the fragmentation events are reduced, it would be expected that the long-term allocation success rate would be higher. Link: http://lkml.kernel.org/r/20181123114528.28802-5-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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64e3d12f |
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06-Nov-2018 |
Kuo-Hsin Yang <vovoy@chromium.org> |
mm, drm/i915: mark pinned shmemfs pages as unevictable The i915 driver uses shmemfs to allocate backing storage for gem objects. These shmemfs pages can be pinned (increased ref count) by shmem_read_mapping_page_gfp(). When a lot of pages are pinned, vmscan wastes a lot of time scanning these pinned pages. In some extreme case, all pages in the inactive anon lru are pinned, and only the inactive anon lru is scanned due to inactive_ratio, the system cannot swap and invokes the oom-killer. Mark these pinned pages as unevictable to speed up vmscan. Export pagevec API check_move_unevictable_pages(). This patch was inspired by Chris Wilson's change [1]. [1]: https://patchwork.kernel.org/patch/9768741/ Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Kuo-Hsin Yang <vovoy@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> # mm part Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Acked-by: Dave Hansen <dave.hansen@intel.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Link: https://patchwork.freedesktop.org/patch/msgid/20181106132324.17390-1-chris@chris-wilson.co.uk Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
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4b85afbd |
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26-Oct-2018 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: zero-seek shrinkers The page cache and most shrinkable slab caches hold data that has been read from disk, but there are some caches that only cache CPU work, such as the dentry and inode caches of procfs and sysfs, as well as the subset of radix tree nodes that track non-resident page cache. Currently, all these are shrunk at the same rate: using DEFAULT_SEEKS for the shrinker's seeks setting tells the reclaim algorithm that for every two page cache pages scanned it should scan one slab object. This is a bogus setting. A virtual inode that required no IO to create is not twice as valuable as a page cache page; shadow cache entries with eviction distances beyond the size of memory aren't either. In most cases, the behavior in practice is still fine. Such virtual caches don't tend to grow and assert themselves aggressively, and usually get picked up before they cause problems. But there are scenarios where that's not true. Our database workloads suffer from two of those. For one, their file workingset is several times bigger than available memory, which has the kernel aggressively create shadow page cache entries for the non-resident parts of it. The workingset code does tell the VM that most of these are expendable, but the VM ends up balancing them 2:1 to cache pages as per the seeks setting. This is a huge waste of memory. These workloads also deal with tens of thousands of open files and use /proc for introspection, which ends up growing the proc_inode_cache to absurdly large sizes - again at the cost of valuable cache space, which isn't a reasonable trade-off, given that proc inodes can be re-created without involving the disk. This patch implements a "zero-seek" setting for shrinkers that results in a target ratio of 0:1 between their objects and IO-backed caches. This allows such virtual caches to grow when memory is available (they do cache/avoid CPU work after all), but effectively disables them as soon as IO-backed objects are under pressure. It then switches the shrinkers for procfs and sysfs metadata, as well as excess page cache shadow nodes, to the new zero-seek setting. Link: http://lkml.kernel.org/r/20181009184732.762-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Domas Mituzas <dmituzas@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@surriel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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eb414681 |
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26-Oct-2018 |
Johannes Weiner <hannes@cmpxchg.org> |
psi: pressure stall information for CPU, memory, and IO When systems are overcommitted and resources become contended, it's hard to tell exactly the impact this has on workload productivity, or how close the system is to lockups and OOM kills. In particular, when machines work multiple jobs concurrently, the impact of overcommit in terms of latency and throughput on the individual job can be enormous. In order to maximize hardware utilization without sacrificing individual job health or risk complete machine lockups, this patch implements a way to quantify resource pressure in the system. A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that expose the percentage of time the system is stalled on CPU, memory, or IO, respectively. Stall states are aggregate versions of the per-task delay accounting delays: cpu: some tasks are runnable but not executing on a CPU memory: tasks are reclaiming, or waiting for swapin or thrashing cache io: tasks are waiting for io completions These percentages of walltime can be thought of as pressure percentages, and they give a general sense of system health and productivity loss incurred by resource overcommit. They can also indicate when the system is approaching lockup scenarios and OOMs. To do this, psi keeps track of the task states associated with each CPU and samples the time they spend in stall states. Every 2 seconds, the samples are averaged across CPUs - weighted by the CPUs' non-idle time to eliminate artifacts from unused CPUs - and translated into percentages of walltime. A running average of those percentages is maintained over 10s, 1m, and 5m periods (similar to the loadaverage). [hannes@cmpxchg.org: doc fixlet, per Randy] Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org [hannes@cmpxchg.org: code optimization] Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org [hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter] Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org [hannes@cmpxchg.org: fix build] Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Daniel Drake <drake@endlessm.com> Tested-by: Suren Baghdasaryan <surenb@google.com> Cc: Christopher Lameter <cl@linux.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <jweiner@fb.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Enderborg <peter.enderborg@sony.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1899ad18 |
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26-Oct-2018 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: workingset: tell cache transitions from workingset thrashing Refaults happen during transitions between workingsets as well as in-place thrashing. Knowing the difference between the two has a range of applications, including measuring the impact of memory shortage on the system performance, as well as the ability to smarter balance pressure between the filesystem cache and the swap-backed workingset. During workingset transitions, inactive cache refaults and pushes out established active cache. When that active cache isn't stale, however, and also ends up refaulting, that's bonafide thrashing. Introduce a new page flag that tells on eviction whether the page has been active or not in its lifetime. This bit is then stored in the shadow entry, to classify refaults as transitioning or thrashing. How many page->flags does this leave us with on 32-bit? 20 bits are always page flags 21 if you have an MMU 23 with the zone bits for DMA, Normal, HighMem, Movable 29 with the sparsemem section bits 30 if PAE is enabled 31 with this patch. So on 32-bit PAE, that leaves 1 bit for distinguishing two NUMA nodes. If that's not enough, the system can switch to discontigmem and re-gain the 6 or 7 sparsemem section bits. Link: http://lkml.kernel.org/r/20180828172258.3185-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Daniel Drake <drake@endlessm.com> Tested-by: Suren Baghdasaryan <surenb@google.com> Cc: Christopher Lameter <cl@linux.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <jweiner@fb.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Enderborg <peter.enderborg@sony.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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68600f62 |
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26-Oct-2018 |
Roman Gushchin <guro@fb.com> |
mm: don't miss the last page because of round-off error I've noticed, that dying memory cgroups are often pinned in memory by a single pagecache page. Even under moderate memory pressure they sometimes stayed in such state for a long time. That looked strange. My investigation showed that the problem is caused by applying the LRU pressure balancing math: scan = div64_u64(scan * fraction[lru], denominator), where denominator = fraction[anon] + fraction[file] + 1. Because fraction[lru] is always less than denominator, if the initial scan size is 1, the result is always 0. This means the last page is not scanned and has no chances to be reclaimed. Fix this by rounding up the result of the division. In practice this change significantly improves the speed of dying cgroups reclaim. [guro@fb.com: prevent double calculation of DIV64_U64_ROUND_UP() arguments] Link: http://lkml.kernel.org/r/20180829213311.GA13501@castle Link: http://lkml.kernel.org/r/20180827162621.30187-3-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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67891fff |
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10-Jun-2018 |
Matthew Wilcox <willy@infradead.org> |
mm: Convert is_page_cache_freeable to XArray This is just a variable rename and comment change. Signed-off-by: Matthew Wilcox <willy@infradead.org>
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4e17ec25 |
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29-Nov-2017 |
Matthew Wilcox <willy@infradead.org> |
mm: Convert delete_from_swap_cache to XArray Both callers of __delete_from_swap_cache have the swp_entry_t already, so pass that in to make constructing the XA_STATE easier. Signed-off-by: Matthew Wilcox <willy@infradead.org>
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b8e57efa |
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05-Oct-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: fix int overflow in callers of do_shrink_slab() do_shrink_slab() returns unsigned long value, and the placing into int variable cuts high bytes off. Then we compare ret and 0xfffffffe (since SHRINK_EMPTY is converted to ret type). Thus a large number of objects returned by do_shrink_slab() may be interpreted as SHRINK_EMPTY, if low bytes of their value are equal to 0xfffffffe. Fix that by declaration ret as unsigned long in these functions. Link: http://lkml.kernel.org/r/153813407177.17544.14888305435570723973.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reported-by: Cyrill Gorcunov <gorcunov@openvz.org> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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172b06c3 |
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20-Sep-2018 |
Roman Gushchin <guro@fb.com> |
mm: slowly shrink slabs with a relatively small number of objects 9092c71bb724 ("mm: use sc->priority for slab shrink targets") changed the way that the target slab pressure is calculated and made it priority-based: delta = freeable >> priority; delta *= 4; do_div(delta, shrinker->seeks); The problem is that on a default priority (which is 12) no pressure is applied at all, if the number of potentially reclaimable objects is less than 4096 (1<<12). This causes the last objects on slab caches of no longer used cgroups to (almost) never get reclaimed. It's obviously a waste of memory. It can be especially painful, if these stale objects are holding a reference to a dying cgroup. Slab LRU lists are reparented on memcg offlining, but corresponding objects are still holding a reference to the dying cgroup. If we don't scan these objects, the dying cgroup can't go away. Most likely, the parent cgroup hasn't any directly charged objects, only remaining objects from dying children cgroups. So it can easily hold a reference to hundreds of dying cgroups. If there are no big spikes in memory pressure, and new memory cgroups are created and destroyed periodically, this causes the number of dying cgroups grow steadily, causing a slow-ish and hard-to-detect memory "leak". It's not a real leak, as the memory can be eventually reclaimed, but it could not happen in a real life at all. I've seen hosts with a steadily climbing number of dying cgroups, which doesn't show any signs of a decline in months, despite the host is loaded with a production workload. It is an obvious waste of memory, and to prevent it, let's apply a minimal pressure even on small shrinker lists. E.g. if there are freeable objects, let's scan at least min(freeable, scan_batch) objects. This fix significantly improves a chance of a dying cgroup to be reclaimed, and together with some previous patches stops the steady growth of the dying cgroups number on some of our hosts. Link: http://lkml.kernel.org/r/20180905230759.12236-1-guro@fb.com Fixes: 9092c71bb724 ("mm: use sc->priority for slab shrink targets") Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Rik van Riel <riel@surriel.com> Cc: Josef Bacik <jbacik@fb.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1c4c3b99 |
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21-Aug-2018 |
Jiang Biao <jiang.biao2@zte.com.cn> |
mm: fix page_freeze_refs and page_unfreeze_refs in comments page_freeze_refs/page_unfreeze_refs have already been relplaced by page_ref_freeze/page_ref_unfreeze , but they are not modified in the comments. Link: http://lkml.kernel.org/r/1532590226-106038-1-git-send-email-jiang.biao2@zte.com.cn Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8df4a44c |
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21-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: check shrinker is memcg-aware in register_shrinker_prepared() There is a sad BUG introduced in patch adding SHRINKER_REGISTERING. shrinker_idr business is only for memcg-aware shrinkers. Only such type of shrinkers have id and they must be finaly installed via idr_replace() in this function. For !memcg-aware shrinkers we never initialize shrinker->id field. But there are all types of shrinkers passed to idr_replace(), and every !memcg-aware shrinker with random ID (most probably, its id is 0) replaces memcg-aware shrinker pointed by the ID in IDR. This patch fixes the problem. Link: http://lkml.kernel.org/r/8ff8a793-8211-713a-4ed9-d6e52390c2fc@virtuozzo.com Fixes: 7e010df53c80 "mm: use special value SHRINKER_REGISTERING instead of list_empty() check" Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reported-by: <syzbot+d5f648a1bfe15678786b@syzkaller.appspotmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Shakeel Butt <shakeelb@google.com> Cc: <syzkaller-bugs@googlegroups.com> Cc: Huang Ying <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7e010df5 |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: use special value SHRINKER_REGISTERING instead of list_empty() check The patch introduces a special value SHRINKER_REGISTERING to use instead of list_empty() to differ a registering shrinker from unregistered shrinker. Why we need that at all? Shrinker registration is split in two parts. The first one is prealloc_shrinker(), which allocates shrinker memory and reserves ID in shrinker_idr. This function can fail. The second is register_shrinker_prepared(), and it finalizes the registration. This function actually makes shrinker available to be used from shrink_slab(), and it can't fail. One shrinker may be based on more then one LRU lists. So, we never clear the bit in memcg shrinker maps, when (one of) corresponding LRU list becomes empty, since other LRU lists may be not empty. See superblock shrinker for example: it is based on two LRU lists: s_inode_lru and s_dentry_lru. We do not want to clear shrinker bit, when there are no inodes in s_inode_lru, as s_dentry_lru may contain dentries. Instead of that, we use special algorithm to detect shrinkers having no elements at all its LRU lists, and this is made in shrink_slab_memcg(). See the comment in this function for the details. Also, in shrink_slab_memcg() we clear shrinker bit in the map, when we meet unregistered shrinker (bit is set, while there is no a shrinker in IDR). Otherwise, we would have done that at the moment of shrinker unregistration for all memcgs (and this looks worse, since iteration over all memcg may take much time). Also this would have imposed restrictions on shrinker unregistration order for its users: they would have had to guarantee, there are no new elements after unregister_shrinker() (otherwise, a new added element would have set a bit). So, if we meet a set bit in map and no shrinker in IDR when we're iterating over the map in shrink_slab_memcg(), this means the corresponding shrinker is unregistered, and we must clear the bit. Another case is shrinker registration. We want two things there: 1) do_shrink_slab() can be called only for completely registered shrinkers; 2) shrinker internal lists may be populated in any order with register_shrinker_prepared() (let's talk on the example with sb). Both of: a)list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru); [cpu0] memcg_set_shrinker_bit(); [cpu0] ... register_shrinker_prepared(); [cpu1] and b)register_shrinker_prepared(); [cpu0] ... list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru); [cpu1] memcg_set_shrinker_bit(); [cpu1] are legitimate. We don't want to impose restriction here and to force people to use only (b) variant. We don't want to force people to care, there is no elements in LRU lists before the shrinker is completely registered. Internal users of LRU lists and shrinker code are two different subsystems, and they have to be closed in themselves each other. In (a) case we have the bit set before shrinker is completely registered. We don't want do_shrink_slab() is called at this moment, so we have to detect such the registering shrinkers. Before this patch list_empty() (shrinker is not linked to the list) check was used for that. So, in (a) there could be a bit set, but we don't call do_shrink_slab() unless shrinker is linked to the list. It's just an indicator, I just overloaded linking to the list. This was not the best solution, since it's better not to touch the shrinker memory from shrink_slab_memcg() before it's completely registered (this also will be useful in the future to make shrink_slab() completely lockless). So, this patch introduces better way to detect registering shrinker, which allows not to dereference shrinker memory. It's just a ~0UL value, which we insert into the IDR during ID allocation. After shrinker is ready to be used, we insert actual shrinker pointer in the IDR, and it becomes available to shrink_slab_memcg(). We can't use NULL instead of this new value for this purpose as: shrink_slab_memcg() already uses NULL to detect unregistered shrinkers, and we don't want the function sees NULL and clears the bit, otherwise (a) won't work. This is the only thing the patch makes: the better way to detect registering shrinker. Nothing else this patch makes. Also this gives a better assembler, but it's minor side of the patch: Before: callq <idr_find> mov %rax,%r15 test %rax,%rax je <shrink_slab_memcg+0x1d5> mov 0x20(%rax),%rax lea 0x20(%r15),%rdx cmp %rax,%rdx je <shrink_slab_memcg+0xbd> mov 0x8(%rsp),%edx mov %r15,%rsi lea 0x10(%rsp),%rdi callq <do_shrink_slab> After: callq <idr_find> mov %rax,%r15 lea -0x1(%rax),%rax cmp $0xfffffffffffffffd,%rax ja <shrink_slab_memcg+0x1cd> mov 0x8(%rsp),%edx mov %r15,%rsi lea 0x10(%rsp),%rdi callq ffffffff810cefd0 <do_shrink_slab> [ktkhai@virtuozzo.com: add #ifdef CONFIG_MEMCG_KMEM around idr_replace()] Link: http://lkml.kernel.org/r/758b8fec-7573-47eb-b26a-7b2847ae7b8c@virtuozzo.com Link: http://lkml.kernel.org/r/153355467546.11522.4518015068123480218.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Matthew Wilcox <willy@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Josef Bacik <jbacik@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ac7fb3ad |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: move check for SHRINKER_NUMA_AWARE to do_shrink_slab() In case of shrink_slab_memcg() we do not zero nid, when shrinker is not numa-aware. This is not a real problem, since currently all memcg-aware shrinkers are numa-aware too (we have two: super_block shrinker and workingset shrinker), but something may change in the future. Link: http://lkml.kernel.org/r/153320759911.18959.8842396230157677671.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Matthew Wilcox <willy@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Josef Bacik <jbacik@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f90280d6 |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: clear shrinker bit if there are no objects related to memcg To avoid further unneed calls of do_shrink_slab() for shrinkers, which already do not have any charged objects in a memcg, their bits have to be cleared. This patch introduces a lockless mechanism to do that without races without parallel list lru add. After do_shrink_slab() returns SHRINK_EMPTY the first time, we clear the bit and call it once again. Then we restore the bit, if the new return value is different. Note, that single smp_mb__after_atomic() in shrink_slab_memcg() covers two situations: 1)list_lru_add() shrink_slab_memcg list_add_tail() for_each_set_bit() <--- read bit do_shrink_slab() <--- missed list update (no barrier) <MB> <MB> set_bit() do_shrink_slab() <--- seen list update This situation, when the first do_shrink_slab() sees set bit, but it doesn't see list update (i.e., race with the first element queueing), is rare. So we don't add <MB> before the first call of do_shrink_slab() instead of this to do not slow down generic case. Also, it's need the second call as seen in below in (2). 2)list_lru_add() shrink_slab_memcg() list_add_tail() ... set_bit() ... ... for_each_set_bit() do_shrink_slab() do_shrink_slab() clear_bit() ... ... ... list_lru_add() ... list_add_tail() clear_bit() <MB> <MB> set_bit() do_shrink_slab() The barriers guarantee that the second do_shrink_slab() in the right side task sees list update if really cleared the bit. This case is drawn in the code comment. [Results/performance of the patchset] After the whole patchset applied the below test shows signify increase of performance: $echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy $mkdir /sys/fs/cgroup/memory/ct $echo 4000M > /sys/fs/cgroup/memory/ct/memory.kmem.limit_in_bytes $for i in `seq 0 4000`; do mkdir /sys/fs/cgroup/memory/ct/$i; echo $$ > /sys/fs/cgroup/memory/ct/$i/cgroup.procs; mkdir -p s/$i; mount -t tmpfs $i s/$i; touch s/$i/file; done Then, 5 sequential calls of drop caches: $time echo 3 > /proc/sys/vm/drop_caches 1)Before: 0.00user 13.78system 0:13.78elapsed 99%CPU 0.00user 5.59system 0:05.60elapsed 99%CPU 0.00user 5.48system 0:05.48elapsed 99%CPU 0.00user 8.35system 0:08.35elapsed 99%CPU 0.00user 8.34system 0:08.35elapsed 99%CPU 2)After 0.00user 1.10system 0:01.10elapsed 99%CPU 0.00user 0.00system 0:00.01elapsed 64%CPU 0.00user 0.01system 0:00.01elapsed 82%CPU 0.00user 0.00system 0:00.01elapsed 64%CPU 0.00user 0.01system 0:00.01elapsed 82%CPU The results show the performance increases at least in 548 times. Shakeel Butt tested this patchset with fork-bomb on his configuration: > I created 255 memcgs, 255 ext4 mounts and made each memcg create a > file containing few KiBs on corresponding mount. Then in a separate > memcg of 200 MiB limit ran a fork-bomb. > > I ran the "perf record -ag -- sleep 60" and below are the results: > > Without the patch series: > Samples: 4M of event 'cycles', Event count (approx.): 3279403076005 > + 36.40% fb.sh [kernel.kallsyms] [k] shrink_slab > + 18.97% fb.sh [kernel.kallsyms] [k] list_lru_count_one > + 6.75% fb.sh [kernel.kallsyms] [k] super_cache_count > + 0.49% fb.sh [kernel.kallsyms] [k] down_read_trylock > + 0.44% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter > + 0.27% fb.sh [kernel.kallsyms] [k] up_read > + 0.21% fb.sh [kernel.kallsyms] [k] osq_lock > + 0.13% fb.sh [kernel.kallsyms] [k] shmem_unused_huge_count > + 0.08% fb.sh [kernel.kallsyms] [k] shrink_node_memcg > + 0.08% fb.sh [kernel.kallsyms] [k] shrink_node > > With the patch series: > Samples: 4M of event 'cycles', Event count (approx.): 2756866824946 > + 47.49% fb.sh [kernel.kallsyms] [k] down_read_trylock > + 30.72% fb.sh [kernel.kallsyms] [k] up_read > + 9.51% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter > + 1.69% fb.sh [kernel.kallsyms] [k] shrink_node_memcg > + 1.35% fb.sh [kernel.kallsyms] [k] mem_cgroup_protected > + 1.05% fb.sh [kernel.kallsyms] [k] queued_spin_lock_slowpath > + 0.85% fb.sh [kernel.kallsyms] [k] _raw_spin_lock > + 0.78% fb.sh [kernel.kallsyms] [k] lruvec_lru_size > + 0.57% fb.sh [kernel.kallsyms] [k] shrink_node > + 0.54% fb.sh [kernel.kallsyms] [k] queue_work_on > + 0.46% fb.sh [kernel.kallsyms] [k] shrink_slab_memcg [ktkhai@virtuozzo.com: v9] Link: http://lkml.kernel.org/r/153112561772.4097.11011071937553113003.stgit@localhost.localdomain Link: http://lkml.kernel.org/r/153063070859.1818.11870882950920963480.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Tested-by: Shakeel Butt <shakeelb@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Li RongQing <lirongqing@baidu.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Roman Gushchin <guro@fb.com> Cc: Sahitya Tummala <stummala@codeaurora.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9b996468 |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: add SHRINK_EMPTY shrinker methods return value We need to distinguish the situations when shrinker has very small amount of objects (see vfs_pressure_ratio() called from super_cache_count()), and when it has no objects at all. Currently, in the both of these cases, shrinker::count_objects() returns 0. The patch introduces new SHRINK_EMPTY return value, which will be used for "no objects at all" case. It's is a refactoring mostly, as SHRINK_EMPTY is replaced by 0 by all callers of do_shrink_slab() in this patch, and all the magic will happen in further. Link: http://lkml.kernel.org/r/153063069574.1818.11037751256699341813.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Tested-by: Shakeel Butt <shakeelb@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Li RongQing <lirongqing@baidu.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Roman Gushchin <guro@fb.com> Cc: Sahitya Tummala <stummala@codeaurora.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
aeed1d32 |
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17-Aug-2018 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm/vmscan.c: generalize shrink_slab() calls in shrink_node() The patch makes shrink_slab() be called for root_mem_cgroup in the same way as it's called for the rest of cgroups. This simplifies the logic and improves the readability. [ktkhai@virtuozzo.com: wrote changelog] Link: http://lkml.kernel.org/r/153063068338.1818.11496084754797453962.stgit@localhost.localdomain Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Tested-by: Shakeel Butt <shakeelb@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Li RongQing <lirongqing@baidu.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Roman Gushchin <guro@fb.com> Cc: Sahitya Tummala <stummala@codeaurora.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b0dedc49 |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm/vmscan.c: iterate only over charged shrinkers during memcg shrink_slab() Using the preparations made in previous patches, in case of memcg shrink, we may avoid shrinkers, which are not set in memcg's shrinkers bitmap. To do that, we separate iterations over memcg-aware and !memcg-aware shrinkers, and memcg-aware shrinkers are chosen via for_each_set_bit() from the bitmap. In case of big nodes, having many isolated environments, this gives significant performance growth. See next patches for the details. Note that the patch does not respect to empty memcg shrinkers, since we never clear the bitmap bits after we set it once. Their shrinkers will be called again, with no shrinked objects as result. This functionality is provided by next patches. [ktkhai@virtuozzo.com: v9] Link: http://lkml.kernel.org/r/153112558507.4097.12713813335683345488.stgit@localhost.localdomain Link: http://lkml.kernel.org/r/153063066653.1818.976035462801487910.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Tested-by: Shakeel Butt <shakeelb@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Li RongQing <lirongqing@baidu.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Roman Gushchin <guro@fb.com> Cc: Sahitya Tummala <stummala@codeaurora.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0a4465d3 |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm, memcg: assign memcg-aware shrinkers bitmap to memcg Imagine a big node with many cpus, memory cgroups and containers. Let we have 200 containers, every container has 10 mounts, and 10 cgroups. All container tasks don't touch foreign containers mounts. If there is intensive pages write, and global reclaim happens, a writing task has to iterate over all memcgs to shrink slab, before it's able to go to shrink_page_list(). Iteration over all the memcg slabs is very expensive: the task has to visit 200 * 10 = 2000 shrinkers for every memcg, and since there are 2000 memcgs, the total calls are 2000 * 2000 = 4000000. So, the shrinker makes 4 million do_shrink_slab() calls just to try to isolate SWAP_CLUSTER_MAX pages in one of the actively writing memcg via shrink_page_list(). I've observed a node spending almost 100% in kernel, making useless iteration over already shrinked slab. This patch adds bitmap of memcg-aware shrinkers to memcg. The size of the bitmap depends on bitmap_nr_ids, and during memcg life it's maintained to be enough to fit bitmap_nr_ids shrinkers. Every bit in the map is related to corresponding shrinker id. Next patches will maintain set bit only for really charged memcg. This will allow shrink_slab() to increase its performance in significant way. See the last patch for the numbers. [ktkhai@virtuozzo.com: v9] Link: http://lkml.kernel.org/r/153112549031.4097.3576147070498769979.stgit@localhost.localdomain [ktkhai@virtuozzo.com: add comment to mem_cgroup_css_online()] Link: http://lkml.kernel.org/r/521f9e5f-c436-b388-fe83-4dc870bfb489@virtuozzo.com Link: http://lkml.kernel.org/r/153063056619.1818.12550500883688681076.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Tested-by: Shakeel Butt <shakeelb@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Li RongQing <lirongqing@baidu.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Roman Gushchin <guro@fb.com> Cc: Sahitya Tummala <stummala@codeaurora.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b4c2b231 |
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17-Aug-2018 |
Kirill Tkhai <ktkhai@virtuozzo.com> |
mm: assign id to every memcg-aware shrinker Introduce shrinker::id number, which is used to enumerate memcg-aware shrinkers. The number start from 0, and the code tries to maintain it as small as possible. This will be used to represent a memcg-aware shrinkers in memcg shrinkers map. Since all memcg-aware shrinkers are based on list_lru, which is per-memcg in case of !CONFIG_MEMCG_KMEM only, the new functionality will be under this config option. [ktkhai@virtuozzo.com: v9] Link: http://lkml.kernel.org/r/153112546435.4097.10607140323811756557.stgit@localhost.localdomain Link: http://lkml.kernel.org/r/153063054586.1818.6041047871606697364.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Tested-by: Shakeel Butt <shakeelb@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <jbacik@fb.com> Cc: Li RongQing <lirongqing@baidu.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Roman Gushchin <guro@fb.com> Cc: Sahitya Tummala <stummala@codeaurora.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bb451fdf |
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17-Aug-2018 |
Greg Thelen <gthelen@google.com> |
mm/vmscan.c: condense scan_control Use smaller scan_control fields for order, priority, and reclaim_idx. Convert fields from int => s8. All easily fit within a byte: - allocation order range: 0..MAX_ORDER(64?) - priority range: 0..12(DEF_PRIORITY) - reclaim_idx range: 0..6(__MAX_NR_ZONES) Since 6538b8ea886e ("x86_64: expand kernel stack to 16K") x86_64 stack overflows are not an issue. But it's inefficient to use ints. Use s8 (signed byte) rather than u8 to allow for loops like: do { ... } while (--sc.priority >= 0); Add BUILD_BUG_ON to verify that s8 is capable of storing max values. This reduces sizeof(struct scan_control): - 96 => 80 bytes (x86_64) - 68 => 56 bytes (i386) scan_control structure field order is changed to utilize padding. After this patch there is 1 bit of scan_control padding. akpm: makes my vmscan.o's .text 572 bytes smaller as well. Link: http://lkml.kernel.org/r/20180530061212.84915-1-gthelen@google.com Signed-off-by: Greg Thelen <gthelen@google.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bf8d5d52 |
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07-Jun-2018 |
Roman Gushchin <guro@fb.com> |
memcg: introduce memory.min Memory controller implements the memory.low best-effort memory protection mechanism, which works perfectly in many cases and allows protecting working sets of important workloads from sudden reclaim. But its semantics has a significant limitation: it works only as long as there is a supply of reclaimable memory. This makes it pretty useless against any sort of slow memory leaks or memory usage increases. This is especially true for swapless systems. If swap is enabled, memory soft protection effectively postpones problems, allowing a leaking application to fill all swap area, which makes no sense. The only effective way to guarantee the memory protection in this case is to invoke the OOM killer. It's possible to handle this case in userspace by reacting on MEMCG_LOW events; but there is still a place for a fail-safe in-kernel mechanism to provide stronger guarantees. This patch introduces the memory.min interface for cgroup v2 memory controller. It works very similarly to memory.low (sharing the same hierarchical behavior), except that it's not disabled if there is no more reclaimable memory in the system. If cgroup is not populated, its memory.min is ignored, because otherwise even the OOM killer wouldn't be able to reclaim the protected memory, and the system can stall. [guro@fb.com: s/low/min/ in docs] Link: http://lkml.kernel.org/r/20180510130758.GA9129@castle.DHCP.thefacebook.com Link: http://lkml.kernel.org/r/20180509180734.GA4856@castle.DHCP.thefacebook.com Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
93781325 |
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07-Jun-2018 |
Omar Sandoval <osandov@fb.com> |
lockdep: fix fs_reclaim annotation While revisiting my Btrfs swapfile series [1], I introduced a situation in which reclaim would lock i_rwsem, and even though the swapon() path clearly made GFP_KERNEL allocations while holding i_rwsem, I got no complaints from lockdep. It turns out that the rework of the fs_reclaim annotation was broken: if the current task has PF_MEMALLOC set, we don't acquire the dummy fs_reclaim lock, but when reclaiming we always check this _after_ we've just set the PF_MEMALLOC flag. In most cases, we can fix this by moving the fs_reclaim_{acquire,release}() outside of the memalloc_noreclaim_{save,restore}(), althought kswapd is slightly different. After applying this, I got the expected lockdep splats. 1: https://lwn.net/Articles/625412/ Link: http://lkml.kernel.org/r/9f8aa70652a98e98d7c4de0fc96a4addcee13efe.1523778026.git.osandov@fb.com Fixes: d92a8cfcb37e ("locking/lockdep: Rework FS_RECLAIM annotation") Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
145e1a71 |
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01-Jun-2018 |
Hugh Dickins <hughd@google.com> |
mm: fix the NULL mapping case in __isolate_lru_page() George Boole would have noticed a slight error in 4.16 commit 69d763fc6d3a ("mm: pin address_space before dereferencing it while isolating an LRU page"). Fix it, to match both the comment above it, and the original behaviour. Although anonymous pages are not marked PageDirty at first, we have an old habit of calling SetPageDirty when a page is removed from swap cache: so there's a category of ex-swap pages that are easily migratable, but were inadvertently excluded from compaction's async migration in 4.16. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1805302014001.12558@eggly.anvils Fixes: 69d763fc6d3a ("mm: pin address_space before dereferencing it while isolating an LRU page") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Ivan Kalvachev <ikalvachev@gmail.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8e04944f |
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04-Apr-2018 |
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
mm,vmscan: Allow preallocating memory for register_shrinker(). syzbot is catching so many bugs triggered by commit 9ee332d99e4d5a97 ("sget(): handle failures of register_shrinker()"). That commit expected that calling kill_sb() from deactivate_locked_super() without successful fill_super() is safe, but the reality was different; some callers assign attributes which are needed for kill_sb() after sget() succeeds. For example, [1] is a report where sb->s_mode (which seems to be either FMODE_READ | FMODE_EXCL | FMODE_WRITE or FMODE_READ | FMODE_EXCL) is not assigned unless sget() succeeds. But it does not worth complicate sget() so that register_shrinker() failure path can safely call kill_block_super() via kill_sb(). Making alloc_super() fail if memory allocation for register_shrinker() failed is much simpler. Let's avoid calling deactivate_locked_super() from sget_userns() by preallocating memory for the shrinker and making register_shrinker() in sget_userns() never fail. [1] https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+5a170e19c963a2e0df79@syzkaller.appspotmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
b93b0163 |
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10-Apr-2018 |
Matthew Wilcox <willy@infradead.org> |
page cache: use xa_lock Remove the address_space ->tree_lock and use the xa_lock newly added to the radix_tree_root. Rename the address_space ->page_tree to ->i_pages, since we don't really care that it's a tree. [willy@infradead.org: fix nds32, fs/dax.c] Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Jeff Layton <jlayton@redhat.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e27be240 |
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10-Apr-2018 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcg: make sure memory.events is uptodate when waking pollers Commit a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat reporting") added per-cpu drift to all memory cgroup stats and events shown in memory.stat and memory.events. For memory.stat this is acceptable. But memory.events issues file notifications, and somebody polling the file for changes will be confused when the counters in it are unchanged after a wakeup. Luckily, the events in memory.events - MEMCG_LOW, MEMCG_HIGH, MEMCG_MAX, MEMCG_OOM - are sufficiently rare and high-level that we don't need per-cpu buffering for them: MEMCG_HIGH and MEMCG_MAX would be the most frequent, but they're counting invocations of reclaim, which is a complex operation that touches many shared cachelines. This splits memory.events from the generic VM events and tracks them in their own, unbuffered atomic counters. That's also cleaner, as it eliminates the ugly enum nesting of VM and cgroup events. [hannes@cmpxchg.org: "array subscript is above array bounds"] Link: http://lkml.kernel.org/r/20180406155441.GA20806@cmpxchg.org Link: http://lkml.kernel.org/r/20180405175507.GA24817@cmpxchg.org Fixes: a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat reporting") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Roman Gushchin <guro@fb.com> Cc: Rik van Riel <riel@surriel.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d51d1e64 |
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10-Apr-2018 |
Steven Rostedt <rostedt@goodmis.org> |
mm, vmscan, tracing: use pointer to reclaim_stat struct in trace event The trace event trace_mm_vmscan_lru_shrink_inactive() currently has 12 parameters! Seven of them are from the reclaim_stat structure. This structure is currently local to mm/vmscan.c. By moving it to the global vmstat.h header, we can also reference it from the vmscan tracepoints. In moving it, it brings down the overhead of passing so many arguments to the trace event. In the future, we may limit the number of arguments that a trace event may pass (ideally just 6, but more realistically it may be 8). Before this patch, the code to call the trace event is this: 0f 83 aa fe ff ff jae ffffffff811e6261 <shrink_inactive_list+0x1e1> 48 8b 45 a0 mov -0x60(%rbp),%rax 45 8b 64 24 20 mov 0x20(%r12),%r12d 44 8b 6d d4 mov -0x2c(%rbp),%r13d 8b 4d d0 mov -0x30(%rbp),%ecx 44 8b 75 cc mov -0x34(%rbp),%r14d 44 8b 7d c8 mov -0x38(%rbp),%r15d 48 89 45 90 mov %rax,-0x70(%rbp) 8b 83 b8 fe ff ff mov -0x148(%rbx),%eax 8b 55 c0 mov -0x40(%rbp),%edx 8b 7d c4 mov -0x3c(%rbp),%edi 8b 75 b8 mov -0x48(%rbp),%esi 89 45 80 mov %eax,-0x80(%rbp) 65 ff 05 e4 f7 e2 7e incl %gs:0x7ee2f7e4(%rip) # 15bd0 <__preempt_count> 48 8b 05 75 5b 13 01 mov 0x1135b75(%rip),%rax # ffffffff8231bf68 <__tracepoint_mm_vmscan_lru_shrink_inactive+0x28> 48 85 c0 test %rax,%rax 74 72 je ffffffff811e646a <shrink_inactive_list+0x3ea> 48 89 c3 mov %rax,%rbx 4c 8b 10 mov (%rax),%r10 89 f8 mov %edi,%eax 48 89 85 68 ff ff ff mov %rax,-0x98(%rbp) 89 f0 mov %esi,%eax 48 89 85 60 ff ff ff mov %rax,-0xa0(%rbp) 89 c8 mov %ecx,%eax 48 89 85 78 ff ff ff mov %rax,-0x88(%rbp) 89 d0 mov %edx,%eax 48 89 85 70 ff ff ff mov %rax,-0x90(%rbp) 8b 45 8c mov -0x74(%rbp),%eax 48 8b 7b 08 mov 0x8(%rbx),%rdi 48 83 c3 18 add $0x18,%rbx 50 push %rax 41 54 push %r12 41 55 push %r13 ff b5 78 ff ff ff pushq -0x88(%rbp) 41 56 push %r14 41 57 push %r15 ff b5 70 ff ff ff pushq -0x90(%rbp) 4c 8b 8d 68 ff ff ff mov -0x98(%rbp),%r9 4c 8b 85 60 ff ff ff mov -0xa0(%rbp),%r8 48 8b 4d 98 mov -0x68(%rbp),%rcx 48 8b 55 90 mov -0x70(%rbp),%rdx 8b 75 80 mov -0x80(%rbp),%esi 41 ff d2 callq *%r10 After the patch: 0f 83 a8 fe ff ff jae ffffffff811e626d <shrink_inactive_list+0x1cd> 8b 9b b8 fe ff ff mov -0x148(%rbx),%ebx 45 8b 64 24 20 mov 0x20(%r12),%r12d 4c 8b 6d a0 mov -0x60(%rbp),%r13 65 ff 05 f5 f7 e2 7e incl %gs:0x7ee2f7f5(%rip) # 15bd0 <__preempt_count> 4c 8b 35 86 5b 13 01 mov 0x1135b86(%rip),%r14 # ffffffff8231bf68 <__tracepoint_mm_vmscan_lru_shrink_inactive+0x28> 4d 85 f6 test %r14,%r14 74 2a je ffffffff811e6411 <shrink_inactive_list+0x371> 49 8b 06 mov (%r14),%rax 8b 4d 8c mov -0x74(%rbp),%ecx 49 8b 7e 08 mov 0x8(%r14),%rdi 49 83 c6 18 add $0x18,%r14 4c 89 ea mov %r13,%rdx 45 89 e1 mov %r12d,%r9d 4c 8d 45 b8 lea -0x48(%rbp),%r8 89 de mov %ebx,%esi 51 push %rcx 48 8b 4d 98 mov -0x68(%rbp),%rcx ff d0 callq *%rax Link: http://lkml.kernel.org/r/2559d7cb-ec60-1200-2362-04fa34fd02bb@fb.com Link: http://lkml.kernel.org/r/20180322121003.4177af15@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reported-by: Alexei Starovoitov <ast@fb.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexei Starovoitov <ast@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e3c1ac58 |
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10-Apr-2018 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/vmscan: don't mess with pgdat->flags in memcg reclaim memcg reclaim may alter pgdat->flags based on the state of LRU lists in cgroup and its children. PGDAT_WRITEBACK may force kswapd to sleep congested_wait(), PGDAT_DIRTY may force kswapd to writeback filesystem pages. But the worst here is PGDAT_CONGESTED, since it may force all direct reclaims to stall in wait_iff_congested(). Note that only kswapd have powers to clear any of these bits. This might just never happen if cgroup limits configured that way. So all direct reclaims will stall as long as we have some congested bdi in the system. Leave all pgdat->flags manipulations to kswapd. kswapd scans the whole pgdat, only kswapd can clear pgdat->flags once node is balanced, thus it's reasonable to leave all decisions about node state to kswapd. Why only kswapd? Why not allow to global direct reclaim change these flags? It is because currently only kswapd can clear these flags. I'm less worried about the case when PGDAT_CONGESTED falsely not set, and more worried about the case when it falsely set. If direct reclaimer sets PGDAT_CONGESTED, do we have guarantee that after the congestion problem is sorted out, kswapd will be woken up and clear the flag? It seems like there is no such guarantee. E.g. direct reclaimers may eventually balance pgdat and kswapd simply won't wake up (see wakeup_kswapd()). Moving pgdat->flags manipulation to kswapd, means that cgroup2 recalim now loses its congestion throttling mechanism. Add per-cgroup congestion state and throttle cgroup2 reclaimers if memcg is in congestion state. Currently there is no need in per-cgroup PGDAT_WRITEBACK and PGDAT_DIRTY bits since they alter only kswapd behavior. The problem could be easily demonstrated by creating heavy congestion in one cgroup: echo "+memory" > /sys/fs/cgroup/cgroup.subtree_control mkdir -p /sys/fs/cgroup/congester echo 512M > /sys/fs/cgroup/congester/memory.max echo $$ > /sys/fs/cgroup/congester/cgroup.procs /* generate a lot of diry data on slow HDD */ while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done & .... while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done & and some job in another cgroup: mkdir /sys/fs/cgroup/victim echo 128M > /sys/fs/cgroup/victim/memory.max # time cat /dev/sda > /dev/null real 10m15.054s user 0m0.487s sys 1m8.505s According to the tracepoint in wait_iff_congested(), the 'cat' spent 50% of the time sleeping there. With the patch, cat don't waste time anymore: # time cat /dev/sda > /dev/null real 5m32.911s user 0m0.411s sys 0m56.664s [aryabinin@virtuozzo.com: congestion state should be per-node] Link: http://lkml.kernel.org/r/20180406135215.10057-1-aryabinin@virtuozzo.com [ayabinin@virtuozzo.com: make congestion state per-cgroup-per-node instead of just per-cgroup[ Link: http://lkml.kernel.org/r/20180406180254.8970-2-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20180323152029.11084-5-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d108c772 |
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10-Apr-2018 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/vmscan: don't change pgdat state on base of a single LRU list state We have separate LRU list for each memory cgroup. Memory reclaim iterates over cgroups and calls shrink_inactive_list() every inactive LRU list. Based on the state of a single LRU shrink_inactive_list() may flag the whole node as dirty,congested or under writeback. This is obviously wrong and hurtful. It's especially hurtful when we have possibly small congested cgroup in system. Than *all* direct reclaims waste time by sleeping in wait_iff_congested(). And the more memcgs in the system we have the longer memory allocation stall is, because wait_iff_congested() called on each lru-list scan. Sum reclaim stats across all visited LRUs on node and flag node as dirty, congested or under writeback based on that sum. Also call congestion_wait(), wait_iff_congested() once per pgdat scan, instead of once per lru-list scan. This only fixes the problem for global reclaim case. Per-cgroup reclaim may alter global pgdat flags too, which is wrong. But that is separate issue and will be addressed in the next patch. This change will not have any effect on a systems with all workload concentrated in a single cgroup. [aryabinin@virtuozzo.com: check nr_writeback against all nr_taken, not just file] Link: http://lkml.kernel.org/r/20180406180254.8970-1-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20180323152029.11084-4-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c4fd4fa5 |
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10-Apr-2018 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/vmscan: remove redundant current_may_throttle() check Only kswapd can have non-zero nr_immediate, and current_may_throttle() is always true for kswapd (PF_LESS_THROTTLE bit is never set) thus it's enough to check stat.nr_immediate only. Link: http://lkml.kernel.org/r/20180315164553.17856-4-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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894befec |
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10-Apr-2018 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/vmscan: update stale comments Update some comments that became stale since transiton from per-zone to per-node reclaim. Link: http://lkml.kernel.org/r/20180315164553.17856-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5ecd9d40 |
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05-Apr-2018 |
David Rientjes <rientjes@google.com> |
mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory Kswapd will not wakeup if per-zone watermarks are not failing or if too many previous attempts at background reclaim have failed. This can be true if there is a lot of free memory available. For high- order allocations, kswapd is responsible for waking up kcompactd for background compaction. If the zone is not below its watermarks or reclaim has recently failed (lots of free memory, nothing left to reclaim), kcompactd does not get woken up. When __GFP_DIRECT_RECLAIM is not allowed, allow kcompactd to still be woken up even if kswapd will not reclaim. This allows high-order allocations, such as thp, to still trigger background compaction even when the zone has an abundance of free memory. Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803111659420.209721@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e830c63a |
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05-Apr-2018 |
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
mm,vmscan: don't pretend forward progress upon shrinker_rwsem contention Since we no longer use return value of shrink_slab() for normal reclaim, the comment is no longer true. If some do_shrink_slab() call takes unexpectedly long (root cause of stall is currently unknown) when register_shrinker()/unregister_shrinker() is pending, trying to drop caches via /proc/sys/vm/drop_caches could become infinite cond_resched() loop if many mem_cgroup are defined. For safety, let's not pretend forward progress. Link: http://lkml.kernel.org/r/201802202229.GGF26507.LVFtMSOOHFJOQF@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e92bb4dd |
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05-Apr-2018 |
Huang Ying <ying.huang@intel.com> |
mm: fix races between address_space dereference and free in page_evicatable When page_mapping() is called and the mapping is dereferenced in page_evicatable() through shrink_active_list(), it is possible for the inode to be truncated and the embedded address space to be freed at the same time. This may lead to the following race. CPU1 CPU2 truncate(inode) shrink_active_list() ... page_evictable(page) truncate_inode_page(mapping, page); delete_from_page_cache(page) spin_lock_irqsave(&mapping->tree_lock, flags); __delete_from_page_cache(page, NULL) page_cache_tree_delete(..) ... mapping = page_mapping(page); page->mapping = NULL; ... spin_unlock_irqrestore(&mapping->tree_lock, flags); page_cache_free_page(mapping, page) put_page(page) if (put_page_testzero(page)) -> false - inode now has no pages and can be freed including embedded address_space mapping_unevictable(mapping) test_bit(AS_UNEVICTABLE, &mapping->flags); - we've dereferenced mapping which is potentially already free. Similar race exists between swap cache freeing and page_evicatable() too. The address_space in inode and swap cache will be freed after a RCU grace period. So the races are fixed via enclosing the page_mapping() and address_space usage in rcu_read_lock/unlock(). Some comments are added in code to make it clear what is protected by the RCU read lock. Link: http://lkml.kernel.org/r/20180212081227.1940-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Minchan Kim <minchan@kernel.org> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1c610d5f |
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22-Mar-2018 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/vmscan: wake up flushers for legacy cgroups too Commit 726d061fbd36 ("mm: vmscan: kick flushers when we encounter dirty pages on the LRU") added flusher invocation to shrink_inactive_list() when many dirty pages on the LRU are encountered. However, shrink_inactive_list() doesn't wake up flushers for legacy cgroup reclaim, so the next commit bbef938429f5 ("mm: vmscan: remove old flusher wakeup from direct reclaim path") removed the only source of flusher's wake up in legacy mem cgroup reclaim path. This leads to premature OOM if there is too many dirty pages in cgroup: # mkdir /sys/fs/cgroup/memory/test # echo $$ > /sys/fs/cgroup/memory/test/tasks # echo 50M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes # dd if=/dev/zero of=tmp_file bs=1M count=100 Killed dd invoked oom-killer: gfp_mask=0x14000c0(GFP_KERNEL), nodemask=(null), order=0, oom_score_adj=0 Call Trace: dump_stack+0x46/0x65 dump_header+0x6b/0x2ac oom_kill_process+0x21c/0x4a0 out_of_memory+0x2a5/0x4b0 mem_cgroup_out_of_memory+0x3b/0x60 mem_cgroup_oom_synchronize+0x2ed/0x330 pagefault_out_of_memory+0x24/0x54 __do_page_fault+0x521/0x540 page_fault+0x45/0x50 Task in /test killed as a result of limit of /test memory: usage 51200kB, limit 51200kB, failcnt 73 memory+swap: usage 51200kB, limit 9007199254740988kB, failcnt 0 kmem: usage 296kB, limit 9007199254740988kB, failcnt 0 Memory cgroup stats for /test: cache:49632KB rss:1056KB rss_huge:0KB shmem:0KB mapped_file:0KB dirty:49500KB writeback:0KB swap:0KB inactive_anon:0KB active_anon:1168KB inactive_file:24760KB active_file:24960KB unevictable:0KB Memory cgroup out of memory: Kill process 3861 (bash) score 88 or sacrifice child Killed process 3876 (dd) total-vm:8484kB, anon-rss:1052kB, file-rss:1720kB, shmem-rss:0kB oom_reaper: reaped process 3876 (dd), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB Wake up flushers in legacy cgroup reclaim too. Link: http://lkml.kernel.org/r/20180315164553.17856-1-aryabinin@virtuozzo.com Fixes: bbef938429f5 ("mm: vmscan: remove old flusher wakeup from direct reclaim path") Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Tested-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9c4e6b1a |
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21-Feb-2018 |
Shakeel Butt <shakeelb@google.com> |
mm, mlock, vmscan: no more skipping pagevecs When a thread mlocks an address space backed either by file pages which are currently not present in memory or swapped out anon pages (not in swapcache), a new page is allocated and added to the local pagevec (lru_add_pvec), I/O is triggered and the thread then sleeps on the page. On I/O completion, the thread can wake on a different CPU, the mlock syscall will then sets the PageMlocked() bit of the page but will not be able to put that page in unevictable LRU as the page is on the pagevec of a different CPU. Even on drain, that page will go to evictable LRU because the PageMlocked() bit is not checked on pagevec drain. The page will eventually go to right LRU on reclaim but the LRU stats will remain skewed for a long time. This patch puts all the pages, even unevictable, to the pagevecs and on the drain, the pages will be added on their LRUs correctly by checking their evictability. This resolves the mlocked pages on pagevec of other CPUs issue because when those pagevecs will be drained, the mlocked file pages will go to unevictable LRU. Also this makes the race with munlock easier to resolve because the pagevec drains happen in LRU lock. However there is still one place which makes a page evictable and does PageLRU check on that page without LRU lock and needs special attention. TestClearPageMlocked() and isolate_lru_page() in clear_page_mlock(). #0: __pagevec_lru_add_fn #1: clear_page_mlock SetPageLRU() if (!TestClearPageMlocked()) return smp_mb() // <--required // inside does PageLRU if (!PageMlocked()) if (isolate_lru_page()) move to evictable LRU putback_lru_page() else move to unevictable LRU In '#1', TestClearPageMlocked() provides full memory barrier semantics and thus the PageLRU check (inside isolate_lru_page) can not be reordered before it. In '#0', without explicit memory barrier, the PageMlocked() check can be reordered before SetPageLRU(). If that happens, '#0' can put a page in unevictable LRU and '#1' might have just cleared the Mlocked bit of that page but fails to isolate as PageLRU fails as '#0' still hasn't set PageLRU bit of that page. That page will be stranded on the unevictable LRU. There is one (good) side effect though. Without this patch, the pages allocated for System V shared memory segment are added to evictable LRUs even after shmctl(SHM_LOCK) on that segment. This patch will correctly put such pages to unevictable LRU. Link: http://lkml.kernel.org/r/20171121211241.18877-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Jan Kara <jack@suse.cz> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a5d09bed |
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06-Feb-2018 |
Mike Rapoport <rppt@linux.vnet.ibm.com> |
mm: docs: add blank lines to silence sphinx "Unexpected indentation" errors Link: http://lkml.kernel.org/r/1516700871-22279-4-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
69d763fc |
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31-Jan-2018 |
Mel Gorman <mgorman@techsingularity.net> |
mm: pin address_space before dereferencing it while isolating an LRU page Minchan Kim asked the following question -- what locks protects address_space destroying when race happens between inode trauncation and __isolate_lru_page? Jan Kara clarified by describing the race as follows CPU1 CPU2 truncate(inode) __isolate_lru_page() ... truncate_inode_page(mapping, page); delete_from_page_cache(page) spin_lock_irqsave(&mapping->tree_lock, flags); __delete_from_page_cache(page, NULL) page_cache_tree_delete(..) ... mapping = page_mapping(page); page->mapping = NULL; ... spin_unlock_irqrestore(&mapping->tree_lock, flags); page_cache_free_page(mapping, page) put_page(page) if (put_page_testzero(page)) -> false - inode now has no pages and can be freed including embedded address_space if (mapping && !mapping->a_ops->migratepage) - we've dereferenced mapping which is potentially already free. The race is theoretically possible but unlikely. Before the delete_from_page_cache, truncate_cleanup_page is called so the page is likely to be !PageDirty or PageWriteback which gets skipped by the only caller that checks the mappping in __isolate_lru_page. Even if the race occurs, a substantial amount of work has to happen during a tiny window with no preemption but it could potentially be done using a virtual machine to artifically slow one CPU or halt it during the critical window. This patch should eliminate the race with truncation by try-locking the page before derefencing mapping and aborting if the lock was not acquired. There was a suggestion from Huang Ying to use RCU as a side-effect to prevent mapping being freed. However, I do not like the solution as it's an unconventional means of preserving a mapping and it's not a context where rcu_read_lock is obviously protecting rcu data. Link: http://lkml.kernel.org/r/20180104102512.2qos3h5vqzeisrek@techsingularity.net Fixes: c82449352854 ("mm: compaction: make isolate_lru_page() filter-aware again") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Minchan Kim <minchan@kernel.org> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a4ef8768 |
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31-Jan-2018 |
Jan Kara <jack@suse.cz> |
mm: remove unused pgdat_reclaimable_pages() Remove unused function pgdat_reclaimable_pages() and node_page_state_snapshot() which becomes unused as well. Link: http://lkml.kernel.org/r/20171122094416.26019-1-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e496612c |
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31-Jan-2018 |
Minchan Kim <minchan@kernel.org> |
mm: do not stall register_shrinker() Shakeel Butt reported he has observed in production systems that the job loader gets stuck for 10s of seconds while doing a mount operation. It turns out that it was stuck in register_shrinker() because some unrelated job was under memory pressure and was spending time in shrink_slab(). Machines have a lot of shrinkers registered and jobs under memory pressure have to traverse all of those memcg-aware shrinkers and affect unrelated jobs which want to register their own shrinkers. To solve the issue, this patch simply bails out slab shrinking if it is found that someone wants to register a shrinker in parallel. A downside is it could cause unfair shrinking between shrinkers. However, it should be rare and we can add compilcated logic if we find it's not enough. [akpm@linux-foundation.org: tweak code comment] Link: http://lkml.kernel.org/r/20171115005602.GB23810@bbox Link: http://lkml.kernel.org/r/1511481899-20335-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Shakeel Butt <shakeelb@google.com> Reported-by: Shakeel Butt <shakeelb@google.com> Tested-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9092c71b |
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31-Jan-2018 |
Josef Bacik <jbacik@fb.com> |
mm: use sc->priority for slab shrink targets Previously we were using the ratio of the number of lru pages scanned to the number of eligible lru pages to determine the number of slab objects to scan. The problem with this is that these two things have nothing to do with each other, so in slab heavy work loads where there is little to no page cache we can end up with the pages scanned being a very low number. This means that we reclaim next to no slab pages and waste a lot of time reclaiming small amounts of space. Consider the following scenario, where we have the following values and the rest of the memory usage is in slab Active: 58840 kB Inactive: 46860 kB Every time we do a get_scan_count() we do this scan = size >> sc->priority where sc->priority starts at DEF_PRIORITY, which is 12. The first loop through reclaim would result in a scan target of 2 pages to 11715 total inactive pages, and 3 pages to 14710 total active pages. This is a really really small target for a system that is entirely slab pages. And this is super optimistic, this assumes we even get to scan these pages. We don't increment sc->nr_scanned unless we 1) isolate the page, which assumes it's not in use, and 2) can lock the page. Under pressure these numbers could probably go down, I'm sure there's some random pages from daemons that aren't actually in use, so the targets get even smaller. Instead use sc->priority in the same way we use it to determine scan amounts for the lru's. This generally equates to pages. Consider the following slab_pages = (nr_objects * object_size) / PAGE_SIZE What we would like to do is scan = slab_pages >> sc->priority but we don't know the number of slab pages each shrinker controls, only the objects. However say that theoretically we knew how many pages a shrinker controlled, we'd still have to convert this to objects, which would look like the following scan = shrinker_pages >> sc->priority scan_objects = (PAGE_SIZE / object_size) * scan or written another way scan_objects = (shrinker_pages >> sc->priority) * (PAGE_SIZE / object_size) which can thus be written scan_objects = ((shrinker_pages * PAGE_SIZE) / object_size) >> sc->priority which is just scan_objects = nr_objects >> sc->priority We don't need to know exactly how many pages each shrinker represents, it's objects are all the information we need. Making this change allows us to place an appropriate amount of pressure on the shrinker pools for their relative size. Link: http://lkml.kernel.org/r/1510780549-6812-1-git-send-email-josef@toxicpanda.com Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Dave Chinner <david@fromorbit.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bb422a73 |
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18-Dec-2017 |
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
mm,vmscan: Make unregister_shrinker() no-op if register_shrinker() failed. Syzbot caught an oops at unregister_shrinker() because combination of commit 1d3d4437eae1bb29 ("vmscan: per-node deferred work") and fault injection made register_shrinker() fail and the caller of register_shrinker() did not check for failure. ---------- [ 554.881422] FAULT_INJECTION: forcing a failure. [ 554.881422] name failslab, interval 1, probability 0, space 0, times 0 [ 554.881438] CPU: 1 PID: 13231 Comm: syz-executor1 Not tainted 4.14.0-rc8+ #82 [ 554.881443] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 554.881445] Call Trace: [ 554.881459] dump_stack+0x194/0x257 [ 554.881474] ? arch_local_irq_restore+0x53/0x53 [ 554.881486] ? find_held_lock+0x35/0x1d0 [ 554.881507] should_fail+0x8c0/0xa40 [ 554.881522] ? fault_create_debugfs_attr+0x1f0/0x1f0 [ 554.881537] ? check_noncircular+0x20/0x20 [ 554.881546] ? find_next_zero_bit+0x2c/0x40 [ 554.881560] ? ida_get_new_above+0x421/0x9d0 [ 554.881577] ? find_held_lock+0x35/0x1d0 [ 554.881594] ? __lock_is_held+0xb6/0x140 [ 554.881628] ? check_same_owner+0x320/0x320 [ 554.881634] ? lock_downgrade+0x990/0x990 [ 554.881649] ? find_held_lock+0x35/0x1d0 [ 554.881672] should_failslab+0xec/0x120 [ 554.881684] __kmalloc+0x63/0x760 [ 554.881692] ? lock_downgrade+0x990/0x990 [ 554.881712] ? register_shrinker+0x10e/0x2d0 [ 554.881721] ? trace_event_raw_event_module_request+0x320/0x320 [ 554.881737] register_shrinker+0x10e/0x2d0 [ 554.881747] ? prepare_kswapd_sleep+0x1f0/0x1f0 [ 554.881755] ? _down_write_nest_lock+0x120/0x120 [ 554.881765] ? memcpy+0x45/0x50 [ 554.881785] sget_userns+0xbcd/0xe20 (...snipped...) [ 554.898693] kasan: CONFIG_KASAN_INLINE enabled [ 554.898724] kasan: GPF could be caused by NULL-ptr deref or user memory access [ 554.898732] general protection fault: 0000 [#1] SMP KASAN [ 554.898737] Dumping ftrace buffer: [ 554.898741] (ftrace buffer empty) [ 554.898743] Modules linked in: [ 554.898752] CPU: 1 PID: 13231 Comm: syz-executor1 Not tainted 4.14.0-rc8+ #82 [ 554.898755] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 554.898760] task: ffff8801d1dbe5c0 task.stack: ffff8801c9e38000 [ 554.898772] RIP: 0010:__list_del_entry_valid+0x7e/0x150 [ 554.898775] RSP: 0018:ffff8801c9e3f108 EFLAGS: 00010246 [ 554.898780] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 554.898784] RDX: 0000000000000000 RSI: ffff8801c53c6f98 RDI: ffff8801c53c6fa0 [ 554.898788] RBP: ffff8801c9e3f120 R08: 1ffff100393c7d55 R09: 0000000000000004 [ 554.898791] R10: ffff8801c9e3ef70 R11: 0000000000000000 R12: 0000000000000000 [ 554.898795] R13: dffffc0000000000 R14: 1ffff100393c7e45 R15: ffff8801c53c6f98 [ 554.898800] FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 554.898804] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 [ 554.898807] CR2: 00000000dbc23000 CR3: 00000001c7269000 CR4: 00000000001406e0 [ 554.898813] DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 [ 554.898816] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 [ 554.898818] Call Trace: [ 554.898828] unregister_shrinker+0x79/0x300 [ 554.898837] ? perf_trace_mm_vmscan_writepage+0x750/0x750 [ 554.898844] ? down_write+0x87/0x120 [ 554.898851] ? deactivate_super+0x139/0x1b0 [ 554.898857] ? down_read+0x150/0x150 [ 554.898864] ? check_same_owner+0x320/0x320 [ 554.898875] deactivate_locked_super+0x64/0xd0 [ 554.898883] deactivate_super+0x141/0x1b0 ---------- Since allowing register_shrinker() callers to call unregister_shrinker() when register_shrinker() failed can simplify error recovery path, this patch makes unregister_shrinker() no-op when register_shrinker() failed. Also, reset shrinker->nr_deferred in case unregister_shrinker() was by error called twice. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Aliaksei Karaliou <akaraliou.dev@gmail.com> Reported-by: syzbot <syzkaller@googlegroups.com> Cc: Glauber Costa <glauber@scylladb.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
2d4894b5 |
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15-Nov-2017 |
Mel Gorman <mgorman@techsingularity.net> |
mm: remove cold parameter from free_hot_cold_page* Most callers users of free_hot_cold_page claim the pages being released are cache hot. The exception is the page reclaim paths where it is likely that enough pages will be freed in the near future that the per-cpu lists are going to be recycled and the cache hotness information is lost. As no one really cares about the hotness of pages being released to the allocator, just ditch the parameter. The APIs are renamed to indicate that it's no longer about hot/cold pages. It should also be less confusing as there are subtle differences between them. __free_pages drops a reference and frees a page when the refcount reaches zero. free_hot_cold_page handled pages whose refcount was already zero which is non-obvious from the name. free_unref_page should be more obvious. No performance impact is expected as the overhead is marginal. The parameter is removed simply because it is a bit stupid to have a useless parameter copied everywhere. [mgorman@techsingularity.net: add pages to head, not tail] Link: http://lkml.kernel.org/r/20171019154321.qtpzaeftoyyw4iey@techsingularity.net Link: http://lkml.kernel.org/r/20171018075952.10627-8-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3a50d14d |
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15-Nov-2017 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm: remove unused pgdat->inactive_ratio Since commit 59dc76b0d4df ("mm: vmscan: reduce size of inactive file list") 'pgdat->inactive_ratio' is not used, except for printing "node_inactive_ratio: 0" in /proc/zoneinfo output. Remove it. Link: http://lkml.kernel.org/r/20171003152611.27483-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b2441318 |
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01-Nov-2017 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
9ba4b2df |
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20-Sep-2017 |
Jens Axboe <axboe@kernel.dk> |
fs: kill 'nr_pages' argument from wakeup_flusher_threads() Everybody is passing in 0 now, let's get rid of the argument. Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
fe490cc0 |
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06-Sep-2017 |
Huang Ying <ying.huang@intel.com> |
mm, THP, swap: add THP swapping out fallback counting When swapping out THP (Transparent Huge Page), instead of swapping out the THP as a whole, sometimes we have to fallback to split the THP into normal pages before swapping, because no free swap clusters are available, or cgroup limit is exceeded, etc. To count the number of the fallback, a new VM event THP_SWPOUT_FALLBACK is added, and counted when we fallback to split the THP. Link: http://lkml.kernel.org/r/20170724051840.2309-13-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bd4c82c2 |
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06-Sep-2017 |
Huang Ying <ying.huang@intel.com> |
mm, THP, swap: delay splitting THP after swapped out In this patch, splitting transparent huge page (THP) during swapping out is delayed from after adding the THP into the swap cache to after swapping out finishes. After the patch, more operations for the anonymous THP reclaiming, such as writing the THP to the swap device, removing the THP from the swap cache could be batched. So that the performance of anonymous THP swapping out could be improved. This is the second step for the THP swap support. The plan is to delay splitting the THP step by step and avoid splitting the THP finally. With the patchset, the swap out throughput improves 42% (from about 5.81GB/s to about 8.25GB/s) in the vm-scalability swap-w-seq test case with 16 processes. At the same time, the IPI (reflect TLB flushing) reduced about 78.9%. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Link: http://lkml.kernel.org/r/20170724051840.2309-12-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
db73ee0d |
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06-Sep-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: do not loop on too_many_isolated for ever Tetsuo Handa has reported[1][2][3] that direct reclaimers might get stuck in too_many_isolated loop basically for ever because the last few pages on the LRU lists are isolated by the kswapd which is stuck on fs locks when doing the pageout or slab reclaim. This in turn means that there is nobody to actually trigger the oom killer and the system is basically unusable. too_many_isolated has been introduced by commit 35cd78156c49 ("vmscan: throttle direct reclaim when too many pages are isolated already") to prevent from pre-mature oom killer invocations because back then no reclaim progress could indeed trigger the OOM killer too early. But since the oom detection rework in commit 0a0337e0d1d1 ("mm, oom: rework oom detection") the allocation/reclaim retry loop considers all the reclaimable pages and throttles the allocation at that layer so we can loosen the direct reclaim throttling. Make shrink_inactive_list loop over too_many_isolated bounded and returns immediately when the situation hasn't resolved after the first sleep. Replace congestion_wait by a simple schedule_timeout_interruptible because we are not really waiting on the IO congestion in this path. Please note that this patch can theoretically cause the OOM killer to trigger earlier while there are many pages isolated for the reclaim which makes progress only very slowly. This would be obvious from the oom report as the number of isolated pages are printed there. If we ever hit this should_reclaim_retry should consider those numbers in the evaluation in one way or another. [1] http://lkml.kernel.org/r/201602092349.ACG81273.OSVtMJQHLOFOFF@I-love.SAKURA.ne.jp [2] http://lkml.kernel.org/r/201702212335.DJB30777.JOFMHSFtVLQOOF@I-love.SAKURA.ne.jp [3] http://lkml.kernel.org/r/201706300914.CEH95859.FMQOLVFHJFtOOS@I-love.SAKURA.ne.jp [mhocko@suse.com: switch to uninterruptible sleep] Link: http://lkml.kernel.org/r/20170724065048.GB25221@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170710074842.23175-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d460acb5 |
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06-Sep-2017 |
Chris Wilson <chris@chris-wilson.co.uk> |
mm: track actual nr_scanned during shrink_slab() Some shrinkers may only be able to free a bunch of objects at a time, and so free more than the requested nr_to_scan in one pass. Whilst other shrinkers may find themselves even unable to scan as many objects as they counted, and so underreport. Account for the extra freed/scanned objects against the total number of objects we intend to scan, otherwise we may end up penalising the slab far more than intended. Similarly, we want to add the underperforming scan to the deferred pass so that we try harder and harder in future passes. Link: http://lkml.kernel.org/r/20170822135325.9191-1-chris@chris-wilson.co.uk Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Shaohua Li <shli@fb.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d92a8cfc |
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03-Mar-2017 |
Peter Zijlstra <peterz@infradead.org> |
locking/lockdep: Rework FS_RECLAIM annotation A while ago someone, and I cannot find the email just now, asked if we could not implement the RECLAIM_FS inversion stuff with a 'fake' lock like we use for other things like workqueues etc. I think this should be possible which allows reducing the 'irq' states and will reduce the amount of __bfs() lookups we do. Removing the 1 IRQ state results in 4 less __bfs() walks per dependency, improving lockdep performance. And by moving this annotation out of the lockdep code it becomes easier for the mm people to extend. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nikolay Borisov <nborisov@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: boqun.feng@gmail.com Cc: iamjoonsoo.kim@lge.com Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: npiggin@gmail.com Cc: walken@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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dcda9b04 |
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12-Jul-2017 |
Michal Hocko <mhocko@suse.com> |
mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic __GFP_REPEAT was designed to allow retry-but-eventually-fail semantic to the page allocator. This has been true but only for allocations requests larger than PAGE_ALLOC_COSTLY_ORDER. It has been always ignored for smaller sizes. This is a bit unfortunate because there is no way to express the same semantic for those requests and they are considered too important to fail so they might end up looping in the page allocator for ever, similarly to GFP_NOFAIL requests. Now that the whole tree has been cleaned up and accidental or misled usage of __GFP_REPEAT flag has been removed for !costly requests we can give the original flag a better name and more importantly a more useful semantic. Let's rename it to __GFP_RETRY_MAYFAIL which tells the user that the allocator would try really hard but there is no promise of a success. This will work independent of the order and overrides the default allocator behavior. Page allocator users have several levels of guarantee vs. cost options (take GFP_KERNEL as an example) - GFP_KERNEL & ~__GFP_RECLAIM - optimistic allocation without _any_ attempt to free memory at all. The most light weight mode which even doesn't kick the background reclaim. Should be used carefully because it might deplete the memory and the next user might hit the more aggressive reclaim - GFP_KERNEL & ~__GFP_DIRECT_RECLAIM (or GFP_NOWAIT)- optimistic allocation without any attempt to free memory from the current context but can wake kswapd to reclaim memory if the zone is below the low watermark. Can be used from either atomic contexts or when the request is a performance optimization and there is another fallback for a slow path. - (GFP_KERNEL|__GFP_HIGH) & ~__GFP_DIRECT_RECLAIM (aka GFP_ATOMIC) - non sleeping allocation with an expensive fallback so it can access some portion of memory reserves. Usually used from interrupt/bh context with an expensive slow path fallback. - GFP_KERNEL - both background and direct reclaim are allowed and the _default_ page allocator behavior is used. That means that !costly allocation requests are basically nofail but there is no guarantee of that behavior so failures have to be checked properly by callers (e.g. OOM killer victim is allowed to fail currently). - GFP_KERNEL | __GFP_NORETRY - overrides the default allocator behavior and all allocation requests fail early rather than cause disruptive reclaim (one round of reclaim in this implementation). The OOM killer is not invoked. - GFP_KERNEL | __GFP_RETRY_MAYFAIL - overrides the default allocator behavior and all allocation requests try really hard. The request will fail if the reclaim cannot make any progress. The OOM killer won't be triggered. - GFP_KERNEL | __GFP_NOFAIL - overrides the default allocator behavior and all allocation requests will loop endlessly until they succeed. This might be really dangerous especially for larger orders. Existing users of __GFP_REPEAT are changed to __GFP_RETRY_MAYFAIL because they already had their semantic. No new users are added. __alloc_pages_slowpath is changed to bail out for __GFP_RETRY_MAYFAIL if there is no progress and we have already passed the OOM point. This means that all the reclaim opportunities have been exhausted except the most disruptive one (the OOM killer) and a user defined fallback behavior is more sensible than keep retrying in the page allocator. [akpm@linux-foundation.org: fix arch/sparc/kernel/mdesc.c] [mhocko@suse.com: semantic fix] Link: http://lkml.kernel.org/r/20170626123847.GM11534@dhcp22.suse.cz [mhocko@kernel.org: address other thing spotted by Vlastimil] Link: http://lkml.kernel.org/r/20170626124233.GN11534@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170623085345.11304-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Alex Belits <alex.belits@cavium.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: David Daney <david.daney@cavium.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: NeilBrown <neilb@suse.com> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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06226226 |
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10-Jul-2017 |
David Rientjes <rientjes@google.com> |
mm, vmscan: avoid thrashing anon lru when free + file is low The purpose of the code that commit 623762517e23 ("revert 'mm: vmscan: do not swap anon pages just because free+file is low'") reintroduces is to prefer swapping anonymous memory rather than trashing the file lru. If the anonymous inactive lru for the set of eligible zones is considered low, however, or the length of the list for the given reclaim priority does not allow for effective anonymous-only reclaiming, then avoid forcing SCAN_ANON. Forcing SCAN_ANON will end up thrashing the small list and leave unreclaimed memory on the file lrus. If the inactive list is insufficient, fallback to balanced reclaim so the file lru doesn't remain untouched. [akpm@linux-foundation.org: fix build] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1705011432220.137835@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Suggested-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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385386cf |
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06-Jul-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmstat: move slab statistics from zone to node counters Patch series "mm: per-lruvec slab stats" Josef is working on a new approach to balancing slab caches and the page cache. For this to work, he needs slab cache statistics on the lruvec level. These patches implement that by adding infrastructure that allows updating and reading generic VM stat items per lruvec, then switches some existing VM accounting sites, including the slab accounting ones, to this new cgroup-aware API. I'll follow up with more patches on this, because there is actually substantial simplification that can be done to the memory controller when we replace private memcg accounting with making the existing VM accounting sites cgroup-aware. But this is enough for Josef to base his slab reclaim work on, so here goes. This patch (of 5): To re-implement slab cache vs. page cache balancing, we'll need the slab counters at the lruvec level, which, ever since lru reclaim was moved from the zone to the node, is the intersection of the node, not the zone, and the memcg. We could retain the per-zone counters for when the page allocator dumps its memory information on failures, and have counters on both levels - which on all but NUMA node 0 is usually redundant. But let's keep it simple for now and just move them. If anybody complains we can restore the per-zone counters. [hannes@cmpxchg.org: fix oops] Link: http://lkml.kernel.org/r/20170605183511.GA8915@cmpxchg.org Link: http://lkml.kernel.org/r/20170530181724.27197-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2262185c |
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06-Jul-2017 |
Roman Gushchin <guro@fb.com> |
mm: per-cgroup memory reclaim stats Track the following reclaim counters for every memory cgroup: PGREFILL, PGSCAN, PGSTEAL, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE and PGLAZYFREED. These values are exposed using the memory.stats interface of cgroup v2. The meaning of each value is the same as for global counters, available using /proc/vmstat. Also, for consistency, rename mem_cgroup_count_vm_event() to count_memcg_event_mm(). Link: http://lkml.kernel.org/r/1494530183-30808-1-git-send-email-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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747552b1 |
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06-Jul-2017 |
Huang Ying <ying.huang@intel.com> |
mm, THP, swap: enable THP swap optimization only if has compound map If there is no compound map for a THP (Transparent Huge Page), it is possible that the map count of some sub-pages of the THP is 0. So it is better to split the THP before swapping out. In this way, the sub-pages not mapped will be freed, and we can avoid the unnecessary swap out operations for these sub-pages. Link: http://lkml.kernel.org/r/20170515112522.32457-6-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b8f593cd |
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06-Jul-2017 |
Huang Ying <ying.huang@intel.com> |
mm, THP, swap: check whether THP can be split firstly To swap out THP (Transparent Huage Page), before splitting the THP, the swap cluster will be allocated and the THP will be added into the swap cache. But it is possible that the THP cannot be split, so that we must delete the THP from the swap cache and free the swap cluster. To avoid that, in this patch, whether the THP can be split is checked firstly. The check can only be done racy, but it is good enough for most cases. With the patch, the swap out throughput improves 3.6% (from about 4.16GB/s to about 4.31GB/s) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Link: http://lkml.kernel.org/r/20170515112522.32457-5-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> [for can_split_huge_page()] Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0f074658 |
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06-Jul-2017 |
Minchan Kim <minchan@kernel.org> |
mm, THP, swap: move anonymous THP split logic to vmscan The add_to_swap aims to allocate swap_space(ie, swap slot and swapcache) so if it fails due to lack of space in case of THP or something(hdd swap but tries THP swapout) *caller* rather than add_to_swap itself should split the THP page and retry it with base page which is more natural. Link: http://lkml.kernel.org/r/20170515112522.32457-4-ying.huang@intel.com Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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75f6d6d2 |
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06-Jul-2017 |
Minchan Kim <minchan@kernel.org> |
mm, THP, swap: unify swap slot free functions to put_swap_page Now, get_swap_page takes struct page and allocates swap space according to page size(ie, normal or THP) so it would be more cleaner to introduce put_swap_page which is a counter function of get_swap_page. Then, it calls right swap slot free function depending on page's size. [ying.huang@intel.com: minor cleanup and fix] Link: http://lkml.kernel.org/r/20170515112522.32457-3-ying.huang@intel.com Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f2f43e56 |
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06-Jul-2017 |
Nick Desaulniers <nick.desaulniers@gmail.com> |
mm/vmscan.c: fix unsequenced modification and access warning Clang and its -Wunsequenced emits a warning mm/vmscan.c:2961:25: error: unsequenced modification and access to 'gfp_mask' [-Wunsequenced] .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)), ^ While it is not clear to me whether the initialization code violates the specification (6.7.8 par 19 (ISO/IEC 9899) looks like it disagrees) the code is quite confusing and worth cleaning up anyway. Fix this by reusing sc.gfp_mask rather than the updated input gfp_mask parameter. Link: http://lkml.kernel.org/r/20170510154030.10720-1-nick.desaulniers@gmail.com Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c6202adf |
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16-May-2017 |
Thomas Gleixner <tglx@linutronix.de> |
mm/vmscan: Adjust system_state checks To enable smp_processor_id() and might_sleep() debug checks earlier, it's required to add system states between SYSTEM_BOOTING and SYSTEM_RUNNING. Adjust the system_state check in kswapd_run() to handle the extra states. Tested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170516184736.119158930@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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791b48b6 |
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12-May-2017 |
Minchan Kim <minchan@kernel.org> |
mm: vmscan: scan until it finds eligible pages Although there are a ton of free swap and anonymous LRU page in elgible zones, OOM happened. balloon invoked oom-killer: gfp_mask=0x17080c0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOTRACK), nodemask=(null), order=0, oom_score_adj=0 CPU: 7 PID: 1138 Comm: balloon Not tainted 4.11.0-rc6-mm1-zram-00289-ge228d67e9677-dirty #17 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 Call Trace: oom_kill_process+0x21d/0x3f0 out_of_memory+0xd8/0x390 __alloc_pages_slowpath+0xbc1/0xc50 __alloc_pages_nodemask+0x1a5/0x1c0 pte_alloc_one+0x20/0x50 __pte_alloc+0x1e/0x110 __handle_mm_fault+0x919/0x960 handle_mm_fault+0x77/0x120 __do_page_fault+0x27a/0x550 trace_do_page_fault+0x43/0x150 do_async_page_fault+0x2c/0x90 async_page_fault+0x28/0x30 Mem-Info: active_anon:424716 inactive_anon:65314 isolated_anon:0 active_file:52 inactive_file:46 isolated_file:0 unevictable:0 dirty:27 writeback:0 unstable:0 slab_reclaimable:3967 slab_unreclaimable:4125 mapped:133 shmem:43 pagetables:1674 bounce:0 free:4637 free_pcp:225 free_cma:0 Node 0 active_anon:1698864kB inactive_anon:261256kB active_file:208kB inactive_file:184kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:532kB dirty:108kB writeback:0kB shmem:172kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no DMA free:7316kB min:32kB low:44kB high:56kB active_anon:8064kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:464kB slab_unreclaimable:40kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 992 992 1952 DMA32 free:9088kB min:2048kB low:3064kB high:4080kB active_anon:952176kB inactive_anon:0kB active_file:36kB inactive_file:0kB unevictable:0kB writepending:88kB present:1032192kB managed:1019388kB mlocked:0kB slab_reclaimable:13532kB slab_unreclaimable:16460kB kernel_stack:3552kB pagetables:6672kB bounce:0kB free_pcp:56kB local_pcp:24kB free_cma:0kB lowmem_reserve[]: 0 0 0 959 Movable free:3644kB min:1980kB low:2960kB high:3940kB active_anon:738560kB inactive_anon:261340kB active_file:188kB inactive_file:640kB unevictable:0kB writepending:20kB present:1048444kB managed:1010816kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:832kB local_pcp:60kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 DMA: 1*4kB (E) 0*8kB 18*16kB (E) 10*32kB (E) 10*64kB (E) 9*128kB (ME) 8*256kB (E) 2*512kB (E) 2*1024kB (E) 0*2048kB 0*4096kB = 7524kB DMA32: 417*4kB (UMEH) 181*8kB (UMEH) 68*16kB (UMEH) 48*32kB (UMEH) 14*64kB (MH) 3*128kB (M) 1*256kB (H) 1*512kB (M) 2*1024kB (M) 0*2048kB 0*4096kB = 9836kB Movable: 1*4kB (M) 1*8kB (M) 1*16kB (M) 1*32kB (M) 0*64kB 1*128kB (M) 2*256kB (M) 4*512kB (M) 1*1024kB (M) 0*2048kB 0*4096kB = 3772kB 378 total pagecache pages 17 pages in swap cache Swap cache stats: add 17325, delete 17302, find 0/27 Free swap = 978940kB Total swap = 1048572kB 524157 pages RAM 0 pages HighMem/MovableOnly 12629 pages reserved 0 pages cma reserved 0 pages hwpoisoned [ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name [ 433] 0 433 4904 5 14 3 82 0 upstart-udev-br [ 438] 0 438 12371 5 27 3 191 -1000 systemd-udevd With investigation, skipping page of isolate_lru_pages makes reclaim void because it returns zero nr_taken easily so LRU shrinking is effectively nothing and just increases priority aggressively. Finally, OOM happens. The problem is that get_scan_count determines nr_to_scan with eligible zones so although priority drops to zero, it couldn't reclaim any pages if the LRU contains mostly ineligible pages. get_scan_count: size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); size = size >> sc->priority; Assumes sc->priority is 0 and LRU list is as follows. N-N-N-N-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H (Ie, small eligible pages are in the head of LRU but others are almost ineligible pages) In that case, size becomes 4 so VM want to scan 4 pages but 4 pages from tail of the LRU are not eligible pages. If get_scan_count counts skipped pages, it doesn't reclaim any pages remained after scanning 4 pages so it ends up OOM happening. This patch makes isolate_lru_pages try to scan pages until it encounters eligible zones's pages. [akpm@linux-foundation.org: clean up mind-bending `for' statement. Tweak comment text] Fixes: 3db65812d688 ("Revert "mm, vmscan: account for skipped pages as a partial scan"") Link: http://lkml.kernel.org/r/1494457232-27401-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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499118e9 |
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08-May-2017 |
Vlastimil Babka <vbabka@suse.cz> |
mm: introduce memalloc_noreclaim_{save,restore} The previous patch ("mm: prevent potential recursive reclaim due to clearing PF_MEMALLOC") has shown that simply setting and clearing PF_MEMALLOC in current->flags can result in wrongly clearing a pre-existing PF_MEMALLOC flag and potentially lead to recursive reclaim. Let's introduce helpers that support proper nesting by saving the previous stat of the flag, similar to the existing memalloc_noio_* and memalloc_nofs_* helpers. Convert existing setting/clearing of PF_MEMALLOC within mm to the new helpers. There are no known issues with the converted code, but the change makes it more robust. Link: http://lkml.kernel.org/r/20170405074700.29871-3-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Boris Brezillon <boris.brezillon@free-electrons.com> Cc: Chris Leech <cleech@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Josef Bacik <jbacik@fb.com> Cc: Lee Duncan <lduncan@suse.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ccda7f43 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: use node page state naming scheme for memcg The memory controllers stat function names are awkwardly long and arbitrarily different from the zone and node stat functions. The current interface is named: mem_cgroup_read_stat() mem_cgroup_update_stat() mem_cgroup_inc_stat() mem_cgroup_dec_stat() mem_cgroup_update_page_stat() mem_cgroup_inc_page_stat() mem_cgroup_dec_page_stat() This patch renames it to match the corresponding node stat functions: memcg_page_state() [node_page_state()] mod_memcg_state() [mod_node_state()] inc_memcg_state() [inc_node_state()] dec_memcg_state() [dec_node_state()] mod_memcg_page_state() [mod_node_page_state()] inc_memcg_page_state() [inc_node_page_state()] dec_memcg_page_state() [dec_node_page_state()] Link: http://lkml.kernel.org/r/20170404220148.28338-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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71cd3113 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: re-use node VM page state enum The current duplication is a high-maintenance mess, and it's painful to add new items or query memcg state from the rest of the VM. This increases the size of the stat array marginally, but we should aim to track all these stats on a per-cgroup level anyway. Link: http://lkml.kernel.org/r/20170404220148.28338-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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31176c78 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: clean up memory.events counting function We only ever count single events, drop the @nr parameter. Rename the function accordingly. Remove low-information kerneldoc. Link: http://lkml.kernel.org/r/20170404220148.28338-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2a2e4885 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: fix IO/refault regression in cache workingset transition Since commit 59dc76b0d4df ("mm: vmscan: reduce size of inactive file list") we noticed bigger IO spikes during changes in cache access patterns. The patch in question shrunk the inactive list size to leave more room for the current workingset in the presence of streaming IO. However, workingset transitions that previously happened on the inactive list are now pushed out of memory and incur more refaults to complete. This patch disables active list protection when refaults are being observed. This accelerates workingset transitions, and allows more of the new set to establish itself from memory, without eating into the ability to protect the established workingset during stable periods. The workloads that were measurably affected for us were hit pretty bad by it, with refault/majfault rates doubling and tripling during cache transitions, and the machines sustaining half-hour periods of 100% IO utilization, where they'd previously have sub-minute peaks at 60-90%. Stateful services that handle user data tend to be more conservative with kernel upgrades. As a result we hit most page cache issues with some delay, as was the case here. The severity seemed to warrant a stable tag. Fixes: 59dc76b0d4df ("mm: vmscan: reduce size of inactive file list") Link: http://lkml.kernel.org/r/20170404220052.27593-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: <stable@vger.kernel.org> [4.7+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
666e5a40 |
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03-May-2017 |
Minchan Kim <minchan@kernel.org> |
mm: make ttu's return boolean try_to_unmap() returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for boolean return. This patch changes it. Link: http://lkml.kernel.org/r/1489555493-14659-8-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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33fc80e2 |
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03-May-2017 |
Minchan Kim <minchan@kernel.org> |
mm: remove SWAP_AGAIN in ttu In 2002, [1] introduced SWAP_AGAIN. At that time, try_to_unmap_one used spin_trylock(&mm->page_table_lock) so it's really easy to contend and fail to hold a lock so SWAP_AGAIN to keep LRU status makes sense. However, now we changed it to mutex-based lock and be able to block without skip pte so there is few of small window to return SWAP_AGAIN so remove SWAP_AGAIN and just return SWAP_FAIL. [1] c48c43e, minimal rmap Link: http://lkml.kernel.org/r/1489555493-14659-7-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ad6b6704 |
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03-May-2017 |
Minchan Kim <minchan@kernel.org> |
mm: remove SWAP_MLOCK in ttu ttu doesn't need to return SWAP_MLOCK. Instead, just return SWAP_FAIL because it means the page is not-swappable so it should move to another LRU list(active or unevictable). putback friends will move it to right list depending on the page's LRU flag. Link: http://lkml.kernel.org/r/1489555493-14659-6-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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18863d3a |
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03-May-2017 |
Minchan Kim <minchan@kernel.org> |
mm: remove SWAP_DIRTY in ttu If we found lazyfree page is dirty, try_to_unmap_one can just SetPageSwapBakced in there like PG_mlocked page and just return with SWAP_FAIL which is very natural because the page is not swappable right now so that vmscan can activate it. There is no point to introduce new return value SWAP_DIRTY in try_to_unmap at the moment. Link: http://lkml.kernel.org/r/1489555493-14659-3-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d6622f63 |
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03-May-2017 |
Yisheng Xie <xieyisheng1@huawei.com> |
mm/vmscan: more restrictive condition for retry in do_try_to_free_pages By reviewing code, I find that when enter do_try_to_free_pages, the may_thrash is always clear, and it will retry shrink zones to tap cgroup's reserves memory by setting may_thrash when the former shrink_zones reclaim nothing. However, when memcg is disabled or on legacy hierarchy, or there do not have any memcg protected by low limit, it should not do this useless retry at all, for we do not have any cgroup's reserves memory to tap, and we have already done hard work but made no progress, which as Michal pointed out in former version, we are trying hard to control the retry logical of page alloctor, and the current additional round of reclaim is just lame. Therefore, to avoid this unneeded retrying and make code more readable, we remove the may_thrash field in scan_control, instead, introduce memcg_low_reclaim and memcg_low_skipped, and only retry when memcg_low_skipped, by setting memcg_low_reclaim. [xieyisheng1@huawei.com: remove may_thrash field, introduce mem_cgroup_reclaim] Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Michal Hocko <mhocko@kernel.org> Suggested-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e716f2eb |
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03-May-2017 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx kswapd is woken to reclaim a node based on a failed allocation request from any eligible zone. Once reclaiming in balance_pgdat(), it will continue reclaiming until there is an eligible zone available for the zone it was woken for. kswapd tracks what zone it was recently woken for in pgdat->kswapd_classzone_idx. If it has not been woken recently, this zone will be 0. However, the decision on whether to sleep is made on kswapd_classzone_idx which is 0 without a recent wakeup request and that classzone does not account for lowmem reserves. This allows kswapd to sleep when a low small zone such as ZONE_DMA is balanced for a GFP_DMA request even if a stream of allocations cannot use that zone. While kswapd may be woken again shortly in the near future there are two consequences -- the pgdat bits that control congestion are cleared prematurely and direct reclaim is more likely as kswapd slept prematurely. This patch flips kswapd_classzone_idx to default to MAX_NR_ZONES (an invalid index) when there has been no recent wakeups. If there are no wakeups, it'll decide whether to sleep based on the highest possible zone available (MAX_NR_ZONES - 1). It then becomes critical that the "pgdat balanced" decisions during reclaim and when deciding to sleep are the same. If there is a mismatch, kswapd can stay awake continually trying to balance tiny zones. simoop was used to evaluate it again. Two of the preparation patches regressed the workload so they are included as the second set of results. Otherwise this patch looks artifically excellent 4.11.0-rc1 4.11.0-rc1 4.11.0-rc1 vanilla clear-v2 keepawake-v2 Amean p50-Read 21670074.18 ( 0.00%) 19786774.76 ( 8.69%) 22668332.52 ( -4.61%) Amean p95-Read 25456267.64 ( 0.00%) 24101956.27 ( 5.32%) 26738688.00 ( -5.04%) Amean p99-Read 29369064.73 ( 0.00%) 27691872.71 ( 5.71%) 30991404.52 ( -5.52%) Amean p50-Write 1390.30 ( 0.00%) 1011.91 ( 27.22%) 924.91 ( 33.47%) Amean p95-Write 412901.57 ( 0.00%) 34874.98 ( 91.55%) 1362.62 ( 99.67%) Amean p99-Write 6668722.09 ( 0.00%) 575449.60 ( 91.37%) 16854.04 ( 99.75%) Amean p50-Allocation 78714.31 ( 0.00%) 84246.26 ( -7.03%) 74729.74 ( 5.06%) Amean p95-Allocation 175533.51 ( 0.00%) 400058.43 (-127.91%) 101609.74 ( 42.11%) Amean p99-Allocation 247003.02 ( 0.00%) 10905600.00 (-4315.17%) 125765.57 ( 49.08%) With this patch on top, write and allocation latencies are massively improved. The read latencies are slightly impaired but it's worth noting that this is mostly due to the IO scheduler and not directly related to reclaim. The vmstats are a bit of a mix but the relevant ones are as follows; 4.10.0-rc7 4.10.0-rc7 4.10.0-rc7 mmots-20170209 clear-v1r25keepawake-v1r25 Swap Ins 0 0 0 Swap Outs 0 608 0 Direct pages scanned 6910672 3132699 6357298 Kswapd pages scanned 57036946 82488665 56986286 Kswapd pages reclaimed 55993488 63474329 55939113 Direct pages reclaimed 6905990 2964843 6352115 Kswapd efficiency 98% 76% 98% Kswapd velocity 12494.375 17597.507 12488.065 Direct efficiency 99% 94% 99% Direct velocity 1513.835 668.306 1393.148 Page writes by reclaim 0.000 4410243.000 0.000 Page writes file 0 4409635 0 Page writes anon 0 608 0 Page reclaim immediate 1036792 14175203 1042571 4.11.0-rc1 4.11.0-rc1 4.11.0-rc1 vanilla clear-v2 keepawake-v2 Swap Ins 0 12 0 Swap Outs 0 838 0 Direct pages scanned 6579706 3237270 6256811 Kswapd pages scanned 61853702 79961486 54837791 Kswapd pages reclaimed 60768764 60755788 53849586 Direct pages reclaimed 6579055 2987453 6256151 Kswapd efficiency 98% 75% 98% Page writes by reclaim 0.000 4389496.000 0.000 Page writes file 0 4388658 0 Page writes anon 0 838 0 Page reclaim immediate 1073573 14473009 982507 Swap-outs are equivalent to baseline. Direct reclaim is reduced but not eliminated. It's worth noting that there are two periods of direct reclaim for this workload. The first is when it switches from preparing the files for the actual test itself. It's a lot of file IO followed by a lot of allocs that reclaims heavily for a brief window. While direct reclaim is lower with clear-v2, it is due to kswapd scanning aggressively and trying to reclaim the world which is not the right thing to do. With the patches applied, there is still direct reclaim but the phase change from "creating work files" to starting multiple threads that allocate a lot of anonymous memory faster than kswapd can reclaim. Scanning/reclaim efficiency is restored by this patch. Page writes from reclaim context are back at 0 which is ideal. Pages immediately reclaimed after IO completes is slightly improved but it is expected this will vary slightly. On UMA, there is almost no change so this is not expected to be a universal win. [mgorman@suse.de: fix ->kswapd_classzone_idx initialization] Link: http://lkml.kernel.org/r/20170406174538.5msrznj6nt6qpbx5@suse.de Link: http://lkml.kernel.org/r/20170309075657.25121-4-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shantanu Goel <sgoel01@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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631b6e08 |
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03-May-2017 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: only clear pgdat congested/dirty/writeback state when balanced A pgdat tracks if recent reclaim encountered too many dirty, writeback or congested pages. The flags control whether kswapd writes pages back from reclaim context, tags pages for immediate reclaim when IO completes, whether processes block on wait_iff_congested and whether kswapd blocks when too many pages marked for immediate reclaim are encountered. The state is cleared in a check function with side-effects. With the patch "mm, vmscan: fix zone balance check in prepare_kswapd_sleep", the timing of when the bits get cleared changed. Due to the way the check works, it'll clear the bits if ZONE_DMA is balanced for a GFP_DMA allocation because it does not account for lowmem reserves properly. For the simoop workload, kswapd is not stalling when it should due to the premature clearing, writing pages from reclaim context like crazy and generally being unhelpful. This patch resets the pgdat bits related to page reclaim only when kswapd is going to sleep. The comparison with simoop is then 4.11.0-rc1 4.11.0-rc1 4.11.0-rc1 vanilla fixcheck-v2 clear-v2 Amean p50-Read 21670074.18 ( 0.00%) 20464344.18 ( 5.56%) 19786774.76 ( 8.69%) Amean p95-Read 25456267.64 ( 0.00%) 25721423.64 ( -1.04%) 24101956.27 ( 5.32%) Amean p99-Read 29369064.73 ( 0.00%) 30174230.76 ( -2.74%) 27691872.71 ( 5.71%) Amean p50-Write 1390.30 ( 0.00%) 1395.28 ( -0.36%) 1011.91 ( 27.22%) Amean p95-Write 412901.57 ( 0.00%) 37737.74 ( 90.86%) 34874.98 ( 91.55%) Amean p99-Write 6668722.09 ( 0.00%) 666489.04 ( 90.01%) 575449.60 ( 91.37%) Amean p50-Allocation 78714.31 ( 0.00%) 86286.22 ( -9.62%) 84246.26 ( -7.03%) Amean p95-Allocation 175533.51 ( 0.00%) 351812.27 (-100.42%) 400058.43 (-127.91%) Amean p99-Allocation 247003.02 ( 0.00%) 6291171.56 (-2447.00%) 10905600.00 (-4315.17%) Read latency is improved, write latency is mostly improved but allocation latency is regressed. kswapd is still reclaiming inefficiently, pages are being written back from writeback context and a host of other issues. However, given the change, it needed to be spelled out why the side-effect was moved. Link: http://lkml.kernel.org/r/20170309075657.25121-3-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shantanu Goel <sgoel01@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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333b0a45 |
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03-May-2017 |
Shantanu Goel <sgoel01@yahoo.com> |
mm, vmscan: fix zone balance check in prepare_kswapd_sleep Patch series "Reduce amount of time kswapd sleeps prematurely", v2. The series is unusual in that the first patch fixes one problem and introduces other issues that are noted in the changelog. Patch 2 makes a minor modification that is worth considering on its own but leaves the kernel in a state where it behaves badly. It's not until patch 3 that there is an improvement against baseline. This was mostly motivated by examining Chris Mason's "simoop" benchmark which puts the VM under similar pressure to HADOOP. It has been reported that the benchmark has regressed severely during the last number of releases. While I cannot reproduce all the same problems Chris experienced due to hardware limitations, there was a number of problems on a 2-socket machine with a single disk. simoop latencies 4.11.0-rc1 4.11.0-rc1 vanilla keepawake-v2 Amean p50-Read 21670074.18 ( 0.00%) 22668332.52 ( -4.61%) Amean p95-Read 25456267.64 ( 0.00%) 26738688.00 ( -5.04%) Amean p99-Read 29369064.73 ( 0.00%) 30991404.52 ( -5.52%) Amean p50-Write 1390.30 ( 0.00%) 924.91 ( 33.47%) Amean p95-Write 412901.57 ( 0.00%) 1362.62 ( 99.67%) Amean p99-Write 6668722.09 ( 0.00%) 16854.04 ( 99.75%) Amean p50-Allocation 78714.31 ( 0.00%) 74729.74 ( 5.06%) Amean p95-Allocation 175533.51 ( 0.00%) 101609.74 ( 42.11%) Amean p99-Allocation 247003.02 ( 0.00%) 125765.57 ( 49.08%) These are latencies. Read/write are threads reading fixed-size random blocks from a simulated database. The allocation latency is mmaping and faulting regions of memory. The p50, 95 and p99 reports the worst latencies for 50% of the samples, 95% and 99% respectively. For example, the report indicates that while the test was running 99% of writes completed 99.75% faster. It's worth noting that on a UMA machine that no difference in performance with simoop was observed so milage will vary. It's noted that there is a slight impact to read latencies but it's mostly due to IO scheduler decisions and offset by the large reduction in other latencies. This patch (of 3): The check in prepare_kswapd_sleep needs to match the one in balance_pgdat since the latter will return as soon as any one of the zones in the classzone is above the watermark. This is specially important for higher order allocations since balance_pgdat will typically reset the order to zero relying on compaction to create the higher order pages. Without this patch, prepare_kswapd_sleep fails to wake up kcompactd since the zone balance check fails. It was first reported against 4.9.7 that kswapd is failing to wake up kcompactd due to a mismatch in the zone balance check between balance_pgdat() and prepare_kswapd_sleep(). balance_pgdat() returns as soon as a single zone satisfies the allocation but prepare_kswapd_sleep() requires all zones to do +the same. This causes prepare_kswapd_sleep() to never succeed except in the order == 0 case and consequently, wakeup_kcompactd() is never called. For the machine that originally motivated this patch, the state of compaction from /proc/vmstat looked this way after a day and a half +of uptime: compact_migrate_scanned 240496 compact_free_scanned 76238632 compact_isolated 123472 compact_stall 1791 compact_fail 29 compact_success 1762 compact_daemon_wake 0 After applying the patch and about 10 hours of uptime the state looks like this: compact_migrate_scanned 59927299 compact_free_scanned 2021075136 compact_isolated 640926 compact_stall 4 compact_fail 2 compact_success 2 compact_daemon_wake 5160 Further notes from Mel that motivated him to pick this patch up and resend it; It was observed for the simoop workload (pressures the VM similar to HADOOP) that kswapd was failing to keep ahead of direct reclaim. The investigation noted that there was a need to rationalise kswapd decisions to reclaim with kswapd decisions to sleep. With this patch on a 2-socket box, there was a 49% reduction in direct reclaim scanning. However, the impact otherwise is extremely negative. Kswapd reclaim efficiency dropped from 98% to 76%. simoop has three latency-related metrics for read, write and allocation (an anonymous mmap and fault). 4.11.0-rc1 4.11.0-rc1 vanilla fixcheck-v2 Amean p50-Read 21670074.18 ( 0.00%) 20464344.18 ( 5.56%) Amean p95-Read 25456267.64 ( 0.00%) 25721423.64 ( -1.04%) Amean p99-Read 29369064.73 ( 0.00%) 30174230.76 ( -2.74%) Amean p50-Write 1390.30 ( 0.00%) 1395.28 ( -0.36%) Amean p95-Write 412901.57 ( 0.00%) 37737.74 ( 90.86%) Amean p99-Write 6668722.09 ( 0.00%) 666489.04 ( 90.01%) Amean p50-Allocation 78714.31 ( 0.00%) 86286.22 ( -9.62%) Amean p95-Allocation 175533.51 ( 0.00%) 351812.27 (-100.42%) Amean p99-Allocation 247003.02 ( 0.00%) 6291171.56 (-2447.00%) Of greater concern is that the patch causes swapping and page writes from kswapd context rose from 0 pages to 4189753 pages during the hour the workload ran for. By and large, the patch has very bad behaviour but easily missed as the impact on a UMA machine is negligible. This patch is included with the data in case a bisection leads to this area. This patch is also a pre-requisite for the rest of the series. Link: http://lkml.kernel.org/r/20170309075657.25121-2-mgorman@techsingularity.net Signed-off-by: Shantanu Goel <sgoel01@yahoo.com> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7dea19f9 |
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03-May-2017 |
Michal Hocko <mhocko@suse.com> |
mm: introduce memalloc_nofs_{save,restore} API GFP_NOFS context is used for the following 5 reasons currently: - to prevent from deadlocks when the lock held by the allocation context would be needed during the memory reclaim - to prevent from stack overflows during the reclaim because the allocation is performed from a deep context already - to prevent lockups when the allocation context depends on other reclaimers to make a forward progress indirectly - just in case because this would be safe from the fs POV - silence lockdep false positives Unfortunately overuse of this allocation context brings some problems to the MM. Memory reclaim is much weaker (especially during heavy FS metadata workloads), OOM killer cannot be invoked because the MM layer doesn't have enough information about how much memory is freeable by the FS layer. In many cases it is far from clear why the weaker context is even used and so it might be used unnecessarily. We would like to get rid of those as much as possible. One way to do that is to use the flag in scopes rather than isolated cases. Such a scope is declared when really necessary, tracked per task and all the allocation requests from within the context will simply inherit the GFP_NOFS semantic. Not only this is easier to understand and maintain because there are much less problematic contexts than specific allocation requests, this also helps code paths where FS layer interacts with other layers (e.g. crypto, security modules, MM etc...) and there is no easy way to convey the allocation context between the layers. Introduce memalloc_nofs_{save,restore} API to control the scope of GFP_NOFS allocation context. This is basically copying memalloc_noio_{save,restore} API we have for other restricted allocation context GFP_NOIO. The PF_MEMALLOC_NOFS flag already exists and it is just an alias for PF_FSTRANS which has been xfs specific until recently. There are no more PF_FSTRANS users anymore so let's just drop it. PF_MEMALLOC_NOFS is now checked in the MM layer and drops __GFP_FS implicitly same as PF_MEMALLOC_NOIO drops __GFP_IO. memalloc_noio_flags is renamed to current_gfp_context because it now cares about both PF_MEMALLOC_NOFS and PF_MEMALLOC_NOIO contexts. Xfs code paths preserve their semantic. kmem_flags_convert() doesn't need to evaluate the flag anymore. This patch shouldn't introduce any functional changes. Let's hope that filesystems will drop direct GFP_NOFS (resp. ~__GFP_FS) usage as much as possible and only use a properly documented memalloc_nofs_{save,restore} checkpoints where they are appropriate. [akpm@linux-foundation.org: fix comment typo, reflow comment] Link: http://lkml.kernel.org/r/20170306131408.9828-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Chris Mason <clm@fb.com> Cc: David Sterba <dsterba@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Brian Foster <bfoster@redhat.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Nikolay Borisov <nborisov@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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802a3a92 |
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03-May-2017 |
Shaohua Li <shli@fb.com> |
mm: reclaim MADV_FREE pages When memory pressure is high, we free MADV_FREE pages. If the pages are not dirty in pte, the pages could be freed immediately. Otherwise we can't reclaim them. We put the pages back to anonumous LRU list (by setting SwapBacked flag) and the pages will be reclaimed in normal swapout way. We use normal page reclaim policy. Since MADV_FREE pages are put into inactive file list, such pages and inactive file pages are reclaimed according to their age. This is expected, because we don't want to reclaim too many MADV_FREE pages before used once pages. Based on Minchan's original patch [minchan@kernel.org: clean up lazyfree page handling] Link: http://lkml.kernel.org/r/20170303025237.GB3503@bbox Link: http://lkml.kernel.org/r/14b8eb1d3f6bf6cc492833f183ac8c304e560484.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a128ca71 |
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03-May-2017 |
Shaohua Li <shli@fb.com> |
mm: delete unnecessary TTU_* flags Patch series "mm: fix some MADV_FREE issues", v5. We are trying to use MADV_FREE in jemalloc. Several issues are found. Without solving the issues, jemalloc can't use the MADV_FREE feature. - Doesn't support system without swap enabled. Because if swap is off, we can't or can't efficiently age anonymous pages. And since MADV_FREE pages are mixed with other anonymous pages, we can't reclaim MADV_FREE pages. In current implementation, MADV_FREE will fallback to MADV_DONTNEED without swap enabled. But in our environment, a lot of machines don't enable swap. This will prevent our setup using MADV_FREE. - Increases memory pressure. page reclaim bias file pages reclaim against anonymous pages. This doesn't make sense for MADV_FREE pages, because those pages could be freed easily and refilled with very slight penality. Even page reclaim doesn't bias file pages, there is still an issue, because MADV_FREE pages and other anonymous pages are mixed together. To reclaim a MADV_FREE page, we probably must scan a lot of other anonymous pages, which is inefficient. In our test, we usually see oom with MADV_FREE enabled and nothing without it. - Accounting. There are two accounting problems. We don't have a global accounting. If the system is abnormal, we don't know if it's a problem from MADV_FREE side. The other problem is RSS accounting. MADV_FREE pages are accounted as normal anon pages and reclaimed lazily, so application's RSS becomes bigger. This confuses our workloads. We have monitoring daemon running and if it finds applications' RSS becomes abnormal, the daemon will kill the applications even kernel can reclaim the memory easily. To address the first the two issues, we can either put MADV_FREE pages into a separate LRU list (Minchan's previous patches and V1 patches), or put them into LRU_INACTIVE_FILE list (suggested by Johannes). The patchset use the second idea. The reason is LRU_INACTIVE_FILE list is tiny nowadays and should be full of used once file pages. So we can still efficiently reclaim MADV_FREE pages there without interference with other anon and active file pages. Putting the pages into inactive file list also has an advantage which allows page reclaim to prioritize MADV_FREE pages and used once file pages. MADV_FREE pages are put into the lru list and clear SwapBacked flag, so PageAnon(page) && !PageSwapBacked(page) will indicate a MADV_FREE pages. These pages will directly freed without pageout if they are clean, otherwise normal swap will reclaim them. For the third issue, the previous post adds global accounting and a separate RSS count for MADV_FREE pages. The problem is we never get accurate accounting for MADV_FREE pages. The pages are mapped to userspace, can be dirtied without notice from kernel side. To get accurate accounting, we could write protect the page, but then there is extra page fault overhead, which people don't want to pay. Jemalloc guys have concerns about the inaccurate accounting, so this post drops the accounting patches temporarily. The info exported to /proc/pid/smaps for MADV_FREE pages are kept, which is the only place we can get accurate accounting right now. This patch (of 6): Johannes pointed out TTU_LZFREE is unnecessary. It's true because we always have the flag set if we want to do an unmap. For cases we don't do an unmap, the TTU_LZFREE part of code should never run. Also the TTU_UNMAP is unnecessary. If no other flags set (for example, TTU_MIGRATION), an unmap is implied. The patch includes Johannes's cleanup and dead TTU_ACTION macro removal code Link: http://lkml.kernel.org/r/4be3ea1bc56b26fd98a54d0a6f70bec63f6d8980.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3db65812 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
Revert "mm, vmscan: account for skipped pages as a partial scan" This reverts commit d7f05528eedb047efe2288cff777676b028747b6. Now that reclaimability of a node is no longer based on the ratio between pages scanned and theoretically reclaimable pages, we can remove accounting tricks for pages skipped due to zone constraints. Link: http://lkml.kernel.org/r/20170228214007.5621-9-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c822f622 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() NR_PAGES_SCANNED counts number of pages scanned since the last page free event in the allocator. This was used primarily to measure the reclaimability of zones and nodes, and determine when reclaim should give up on them. In that role, it has been replaced in the preceding patches by a different mechanism. Being implemented as an efficient vmstat counter, it was automatically exported to userspace as well. It's however unlikely that anyone outside the kernel is using this counter in any meaningful way. Remove the counter and the unused pgdat_reclaimable(). Link: http://lkml.kernel.org/r/20170228214007.5621-8-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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688035f7 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: don't avoid high-priority reclaim on memcg limit reclaim Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets") sought to avoid high reclaim priorities for memcg by forcing it to scan a minimum amount of pages when lru_pages >> priority yielded nothing. This was done at a time when reclaim decisions like dirty throttling were tied to the priority level. Nowadays, the only meaningful thing still tied to priority dropping below DEF_PRIORITY - 2 is gating whether laptop_mode=1 is generally allowed to write. But that is from an era where direct reclaim was still allowed to call ->writepage, and kswapd nowadays avoids writes until it's scanned every clean page in the system. Potential changes to how quick sc->may_writepage could trigger are of little concern. Remove the force_scan stuff, as well as the ugly multi-pass target calculation that it necessitated. Link: http://lkml.kernel.org/r/20170228214007.5621-7-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a2d7f8e4 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: don't avoid high-priority reclaim on unreclaimable nodes Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets") sought to avoid high reclaim priorities for kswapd by forcing it to scan a minimum amount of pages when lru_pages >> priority yielded nothing. Commit b95a2f2d486d ("mm: vmscan: convert global reclaim to per-memcg LRU lists"), due to switching global reclaim to a round-robin scheme over all cgroups, had to restrict this forceful behavior to unreclaimable zones in order to prevent massive overreclaim with many cgroups. The latter patch effectively neutered the behavior completely for all but extreme memory pressure. But in those situations we might as well drop the reclaimers to lower priority levels. Remove the check. Link: http://lkml.kernel.org/r/20170228214007.5621-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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047d72c3 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: remove seemingly spurious reclaimability check from laptop_mode gating Commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes") allowed laptop_mode=1 to start writing not just when the priority drops to DEF_PRIORITY - 2 but also when the node is unreclaimable. That appears to be a spurious change in this patch as I doubt the series was tested with laptop_mode, and neither is that particular change mentioned in the changelog. Remove it, it's still recent. Link: http://lkml.kernel.org/r/20170228214007.5621-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d450abd8 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling PF_MEMALLOC direct reclaimers get throttled on a node when the sum of all free pages in each zone fall below half the min watermark. During the summation, we want to exclude zones that don't have reclaimables. Checking the same pgdat over and over again doesn't make sense. Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node") Link: http://lkml.kernel.org/r/20170228214007.5621-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c73322d0 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Patch series "mm: kswapd spinning on unreclaimable nodes - fixes and cleanups". Jia reported a scenario in which the kswapd of a node indefinitely spins at 100% CPU usage. We have seen similar cases at Facebook. The kernel's current method of judging its ability to reclaim a node (or whether to back off and sleep) is based on the amount of scanned pages in proportion to the amount of reclaimable pages. In Jia's and our scenarios, there are no reclaimable pages in the node, however, and the condition for backing off is never met. Kswapd busyloops in an attempt to restore the watermarks while having nothing to work with. This series reworks the definition of an unreclaimable node based not on scanning but on whether kswapd is able to actually reclaim pages in MAX_RECLAIM_RETRIES (16) consecutive runs. This is the same criteria the page allocator uses for giving up on direct reclaim and invoking the OOM killer. If it cannot free any pages, kswapd will go to sleep and leave further attempts to direct reclaim invocations, which will either make progress and re-enable kswapd, or invoke the OOM killer. Patch #1 fixes the immediate problem Jia reported, the remainder are smaller fixlets, cleanups, and overall phasing out of the old method. Patch #6 is the odd one out. It's a nice cleanup to get_scan_count(), and directly related to #5, but in itself not relevant to the series. If the whole series is too ambitious for 4.11, I would consider the first three patches fixes, the rest cleanups. This patch (of 9): Jia He reports a problem with kswapd spinning at 100% CPU when requesting more hugepages than memory available in the system: $ echo 4000 >/proc/sys/vm/nr_hugepages top - 13:42:59 up 3:37, 1 user, load average: 1.09, 1.03, 1.01 Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.0 us, 12.5 sy, 0.0 ni, 85.5 id, 2.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 31371520 total, 30915136 used, 456384 free, 320 buffers KiB Swap: 6284224 total, 115712 used, 6168512 free. 48192 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 76 root 20 0 0 0 0 R 100.0 0.000 217:17.29 kswapd3 At that time, there are no reclaimable pages left in the node, but as kswapd fails to restore the high watermarks it refuses to go to sleep. Kswapd needs to back away from nodes that fail to balance. Up until commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes") kswapd had such a mechanism. It considered zones whose theoretically reclaimable pages it had reclaimed six times over as unreclaimable and backed away from them. This guard was erroneously removed as the patch changed the definition of a balanced node. However, simply restoring this code wouldn't help in the case reported here: there *are* no reclaimable pages that could be scanned until the threshold is met. Kswapd would stay awake anyway. Introduce a new and much simpler way of backing off. If kswapd runs through MAX_RECLAIM_RETRIES (16) cycles without reclaiming a single page, make it back off from the node. This is the same number of shots direct reclaim takes before declaring OOM. Kswapd will go to sleep on that node until a direct reclaimer manages to reclaim some pages, thus proving the node reclaimable again. [hannes@cmpxchg.org: check kswapd failure against the cumulative nr_reclaimed count] Link: http://lkml.kernel.org/r/20170306162410.GB2090@cmpxchg.org [shakeelb@google.com: fix condition for throttle_direct_reclaim] Link: http://lkml.kernel.org/r/20170314183228.20152-1-shakeelb@google.com Link: http://lkml.kernel.org/r/20170228214007.5621-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Shakeel Butt <shakeelb@google.com> Reported-by: Jia He <hejianet@gmail.com> Tested-by: Jia He <hejianet@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5b3cc15a |
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02-Feb-2017 |
Ingo Molnar <mingo@kernel.org> |
sched/headers: Prepare to move the memalloc_noio_*() APIs to <linux/sched/mm.h> Update the .c files that depend on these APIs. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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c2f83143 |
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24-Feb-2017 |
Mel Gorman <mgorman@suse.de> |
mm, vmscan: clear PGDAT_WRITEBACK when zone is balanced Hillf Danton pointed out that since commit 1d82de618dd ("mm, vmscan: make kswapd reclaim in terms of nodes") that PGDAT_WRITEBACK is no longer cleared. It was not noticed as triggering it requires pages under writeback to cycle twice through the LRU and before kswapd gets stalled. Historically, such issues tended to occur on small machines writing heavily to slow storage such as a USB stick. Once kswapd stalls, direct reclaim stalls may be higher but due to the fact that memory pressure is required, it would not be very noticable. Michal Hocko suggested removing the flag entirely but the conservative fix is to restore the intended PGDAT_WRITEBACK behaviour and clear the flag when a suitable zone is balanced. Fixes: 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes") Link: http://lkml.kernel.org/r/20170203203222.gq7hk66yc36lpgtb@suse.de Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c55e8d03 |
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24-Feb-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: move dirty pages out of the way until they're flushed We noticed a performance regression when moving hadoop workloads from 3.10 kernels to 4.0 and 4.6. This is accompanied by increased pageout activity initiated by kswapd as well as frequent bursts of allocation stalls and direct reclaim scans. Even lowering the dirty ratios to the equivalent of less than 1% of memory would not eliminate the issue, suggesting that dirty pages concentrate where the scanner is looking. This can be traced back to recent efforts of thrash avoidance. Where 3.10 would not detect refaulting pages and continuously supply clean cache to the inactive list, a thrashing workload on 4.0+ will detect and activate refaulting pages right away, distilling used-once pages on the inactive list much more effectively. This is by design, and it makes sense for clean cache. But for the most part our workload's cache faults are refaults and its use-once cache is from streaming writes. We end up with most of the inactive list dirty, and we don't go after the active cache as long as we have use-once pages around. But waiting for writes to avoid reclaiming clean cache that *might* refault is a bad trade-off. Even if the refaults happen, reads are faster than writes. Before getting bogged down on writeback, reclaim should first look at *all* cache in the system, even active cache. To accomplish this, activate pages that are dirty or under writeback when they reach the end of the inactive LRU. The pages are marked for immediate reclaim, meaning they'll get moved back to the inactive LRU tail as soon as they're written back and become reclaimable. But in the meantime, by reducing the inactive list to only immediately reclaimable pages, we allow the scanner to deactivate and refill the inactive list with clean cache from the active list tail to guarantee forward progress. [hannes@cmpxchg.org: update comment] Link: http://lkml.kernel.org/r/20170202191957.22872-8-hannes@cmpxchg.org Link: http://lkml.kernel.org/r/20170123181641.23938-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4eda4823 |
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24-Feb-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: only write dirty pages that the scanner has seen twice Dirty pages can easily reach the end of the LRU while there are still clean pages to reclaim around. Don't let kswapd write them back just because there are a lot of them. It costs more CPU to find the clean pages, but that's almost certainly better than to disrupt writeback from the flushers with LRU-order single-page writes from reclaim. And the flushers have been woken up by that point, so we spend IO capacity on flushing and CPU capacity on finding the clean cache. Only start writing dirty pages if they have cycled around the LRU twice now and STILL haven't been queued on the IO device. It's possible that the dirty pages are so sparsely distributed across different bdis, inodes, memory cgroups, that the flushers take forever to get to the ones we want reclaimed. Once we see them twice on the LRU, we know that's the quicker way to find them, so do LRU writeback. Link: http://lkml.kernel.org/r/20170123181641.23938-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bbef9384 |
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24-Feb-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: remove old flusher wakeup from direct reclaim path Direct reclaim has been replaced by kswapd reclaim in pretty much all common memory pressure situations, so this code most likely doesn't accomplish the described effect anymore. The previous patch wakes up flushers for all reclaimers when we encounter dirty pages at the tail end of the LRU. Remove the crufty old direct reclaim invocation. Link: http://lkml.kernel.org/r/20170123181641.23938-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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726d061f |
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24-Feb-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: kick flushers when we encounter dirty pages on the LRU Memory pressure can put dirty pages at the end of the LRU without anybody running into dirty limits. Don't start writing individual pages from kswapd while the flushers might be asleep. Unlike the old direct reclaim flusher wakeup (removed in the next patch) that flushes the number of pages just scanned, this patch wakes the flushers for all outstanding dirty pages. That seemed to perform better in a synthetic test that pushes dirty pages to the end of the LRU and into reclaim, because we know LRU aging outstrips writeback already, and this way we give younger dirty pages a headstart rather than wait until reclaim runs into them as well. It also means less plugging and risk of exhausting the struct request pool from reclaim. There is a concern that this will cause temporary files that used to get dirtied and truncated before writeback to now get written to disk under memory pressure. If this turns out to be a real problem, we'll have to revisit this and tame the reclaim flusher wakeups. [hannes@cmpxchg.org: mention dirty expiration as a condition] Link: http://lkml.kernel.org/r/20170126174739.GA30636@cmpxchg.org Link: http://lkml.kernel.org/r/20170123181641.23938-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1276ad68 |
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24-Feb-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: scan dirty pages even in laptop mode Patch series "mm: vmscan: fix kswapd writeback regression". We noticed a regression on multiple hadoop workloads when moving from 3.10 to 4.0 and 4.6, which involves kswapd getting tangled up in page writeout, causing direct reclaim herds that also don't make progress. I tracked it down to the thrash avoidance efforts after 3.10 that make the kernel better at keeping use-once cache and use-many cache sorted on the inactive and active list, with more aggressive protection of the active list as long as there is inactive cache. Unfortunately, our workload's use-once cache is mostly from streaming writes. Waiting for writes to avoid potential reloads in the future is not a good tradeoff. These patches do the following: 1. Wake the flushers when kswapd sees a lump of dirty pages. It's possible to be below the dirty background limit and still have cache velocity push them through the LRU. So start a-flushin'. 2. Let kswapd only write pages that have been rotated twice. This makes sure we really tried to get all the clean pages on the inactive list before resorting to horrible LRU-order writeback. 3. Move rotating dirty pages off the inactive list. Instead of churning or waiting on page writeback, we'll go after clean active cache. This might lead to thrashing, but in this state memory demand outstrips IO speed anyway, and reads are faster than writes. Mel backported the series to 4.10-rc5 with one minor conflict and ran a couple of tests on it. Mix of read/write random workload didn't show anything interesting. Write-only database didn't show much difference in performance but there were slight reductions in IO -- probably in the noise. simoop did show big differences although not as big as Mel expected. This is Chris Mason's workload that similate the VM activity of hadoop. Mel won't go through the full details but over the samples measured during an hour it reported 4.10.0-rc5 4.10.0-rc5 vanilla johannes-v1r1 Amean p50-Read 21346531.56 ( 0.00%) 21697513.24 ( -1.64%) Amean p95-Read 24700518.40 ( 0.00%) 25743268.98 ( -4.22%) Amean p99-Read 27959842.13 ( 0.00%) 28963271.11 ( -3.59%) Amean p50-Write 1138.04 ( 0.00%) 989.82 ( 13.02%) Amean p95-Write 1106643.48 ( 0.00%) 12104.00 ( 98.91%) Amean p99-Write 1569213.22 ( 0.00%) 36343.38 ( 97.68%) Amean p50-Allocation 85159.82 ( 0.00%) 79120.70 ( 7.09%) Amean p95-Allocation 204222.58 ( 0.00%) 129018.43 ( 36.82%) Amean p99-Allocation 278070.04 ( 0.00%) 183354.43 ( 34.06%) Amean final-p50-Read 21266432.00 ( 0.00%) 21921792.00 ( -3.08%) Amean final-p95-Read 24870912.00 ( 0.00%) 26116096.00 ( -5.01%) Amean final-p99-Read 28147712.00 ( 0.00%) 29523968.00 ( -4.89%) Amean final-p50-Write 1130.00 ( 0.00%) 977.00 ( 13.54%) Amean final-p95-Write 1033216.00 ( 0.00%) 2980.00 ( 99.71%) Amean final-p99-Write 1517568.00 ( 0.00%) 32672.00 ( 97.85%) Amean final-p50-Allocation 86656.00 ( 0.00%) 78464.00 ( 9.45%) Amean final-p95-Allocation 211712.00 ( 0.00%) 116608.00 ( 44.92%) Amean final-p99-Allocation 287232.00 ( 0.00%) 168704.00 ( 41.27%) The latencies are actually completely horrific in comparison to 4.4 (and 4.10-rc5 is worse than 4.9 according to historical data for reasons Mel hasn't analysed yet). Still, 95% of write latency (p95-write) is halved by the series and allocation latency is way down. Direct reclaim activity is one fifth of what it was according to vmstats. Kswapd activity is higher but this is not necessarily surprising. Kswapd efficiency is unchanged at 99% (99% of pages scanned were reclaimed) but direct reclaim efficiency went from 77% to 99% In the vanilla kernel, 627MB of data was written back from reclaim context. With the series, no data was written back. With or without the patch, pages are being immediately reclaimed after writeback completes. However, with the patch, only 1/8th of the pages are reclaimed like this. This patch (of 5): We have an elaborate dirty/writeback throttling mechanism inside the reclaim scanner, but for that to work the pages have to go through shrink_page_list() and get counted for what they are. Otherwise, we mess up the LRU order and don't match reclaim speed to writeback. Especially during deactivation, there is never a reason to skip dirty pages; nothing is even trying to write them out from there. Don't mess up the LRU order for nothing, shuffle these pages along. Link: http://lkml.kernel.org/r/20170123181641.23938-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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abd6e8a7 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
Revert "mm: bail out in shrink_inactive_list()" This reverts commit 91dcade47a3d0e7. inactive_reclaimable_pages shouldn't be needed anymore since that get_scan_count is aware of the eligble zones ("mm, vmscan: consider eligible zones in get_scan_count"). Link: http://lkml.kernel.org/r/20170117103702.28542-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpchxg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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71ab6cfe |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: consider eligible zones in get_scan_count get_scan_count() considers the whole node LRU size when - doing SCAN_FILE due to many page cache inactive pages - calculating the number of pages to scan In both cases this might lead to unexpected behavior especially on 32b systems where we can expect lowmem memory pressure very often. A large highmem zone can easily distort SCAN_FILE heuristic because there might be only few file pages from the eligible zones on the node lru and we would still enforce file lru scanning which can lead to trashing while we could still scan anonymous pages. The later use of lruvec_lru_size can be problematic as well. Especially when there are not many pages from the eligible zones. We would have to skip over many pages to find anything to reclaim but shrink_node_memcg would only reduce the remaining number to scan by SWAP_CLUSTER_MAX at maximum. Therefore we can end up going over a large LRU many times without actually having chance to reclaim much if anything at all. The closer we are out of memory on lowmem zone the worse the problem will be. Fix this by filtering out all the ineligible zones when calculating the lru size for both paths and consider only sc->reclaim_idx zones. The patch would need to be tweaked a bit to apply to 4.10 and older but I will do that as soon as it hits the Linus tree in the next merge window. Link: http://lkml.kernel.org/r/20170117103702.28542-3-mhocko@kernel.org Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis") Signed-off-by: Michal Hocko <mhocko@suse.com> Tested-by: Trevor Cordes <trevor@tecnopolis.ca> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fd538803 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: cleanup lru size claculations lruvec_lru_size returns the full size of the LRU list while we sometimes need a value reduced only to eligible zones (e.g. for lowmem requests). inactive_list_is_low is one such user. Later patches will add more of them. Add a new parameter to lruvec_lru_size and allow it filter out zones which are not eligible for the given context. Link: http://lkml.kernel.org/r/20170117103702.28542-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f0958906 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: do not count freed pages as PGDEACTIVATE PGDEACTIVATE represents the number of pages moved from the active list to the inactive list. At least this sounds like the original motivation of the counter. move_active_pages_to_lru, however, counts pages which got freed in the mean time as deactivated as well. This is a very rare event and counting them as deactivation in itself is not harmful but it makes the code more convoluted than necessary - we have to count both all pages and those which are freed which is a bit confusing. After this patch the PGDEACTIVATE should have a slightly more clear semantic and only count those pages which are moved from the active to the inactive list which is a plus. Link: http://lkml.kernel.org/r/20170112211221.17636-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dcec0b60 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint Currently we have tracepoints for both active and inactive LRU lists reclaim but we do not have any which would tell us why we we decided to age the active list. Without that it is quite hard to diagnose active/inactive lists balancing. Add mm_vmscan_inactive_list_is_low tracepoint to tell us this information. Link: http://lkml.kernel.org/r/20170104101942.4860-8-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5bccd166 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint mm_vmscan_lru_shrink_inactive will currently report the number of scanned and reclaimed pages. This doesn't give us an idea how the reclaim went except for the overall effectiveness though. Export and show other counters which will tell us why we couldn't reclaim some pages. - nr_dirty, nr_writeback, nr_congested and nr_immediate tells us how many pages are blocked due to IO - nr_activate tells us how many pages were moved to the active list - nr_ref_keep reports how many pages are kept on the LRU due to references (mostly for the file pages which are about to go for another round through the inactive list) - nr_unmap_fail - how many pages failed to unmap All these are rather low level so they might change in future but the tracepoint is already implementation specific so no tools should be depending on its stability. Link: http://lkml.kernel.org/r/20170104101942.4860-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3c710c1a |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: extract shrink_page_list reclaim counters into a struct shrink_page_list returns quite some counters back to its caller. Extract the existing 5 into struct reclaim_stat because this makes the code easier to follow and also allows further counters to be returned. While we are at it, make all of them unsigned rather than unsigned long as we do not really need full 64b for them (we never scan more than SWAP_CLUSTER_MAX pages at once). This should reduce some stack space. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20170104101942.4860-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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32b3f297 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint mm_vmscan_lru_isolate currently prints only whether the LRU we isolate from is file or anonymous but we do not know which LRU this is. It is useful to know whether the list is active or inactive, since we are using the same function to isolate pages from both of them and it's hard to distinguish otherwise. Link: http://lkml.kernel.org/r/20170104101942.4860-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1265e3a6 |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate mm_vmscan_lru_isolate shows the number of requested, scanned and taken pages. This is mostly OK but on 32b systems the number of scanned pages is quite misleading because it includes both the scanned and skipped pages. Moreover the skipped part is scaled based on the number of taken pages. Let's report the exact numbers without any additional logic and add the number of skipped pages. This should make the reported data much more easier to interpret. Link: http://lkml.kernel.org/r/20170104101942.4860-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9d998b4f |
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22-Feb-2017 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: add active list aging tracepoint Our reclaim process has several tracepoints to tell us more about how things are progressing. We are, however, missing a tracepoint to track active list aging. Introduce mm_vmscan_lru_shrink_active which reports the number of - nr_taken is number of isolated pages from the active list - nr_referenced pages which tells us that we are hitting referenced pages which are deactivated. If this is a large part of the reported nr_deactivated pages then we might be hitting into the active list too early because they might be still part of the working set. This might help to debug performance issues. - nr_active pages which tells us how many pages are kept on the active list - mostly exec file backed pages. A high number can indicate that we might be trashing on executables. [mhocko@suse.com: update] Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b4536f0c8 |
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10-Jan-2017 |
Michal Hocko <mhocko@suse.com> |
mm, memcg: fix the active list aging for lowmem requests when memcg is enabled Nils Holland and Klaus Ethgen have reported unexpected OOM killer invocations with 32b kernel starting with 4.8 kernels kworker/u4:5 invoked oom-killer: gfp_mask=0x2400840(GFP_NOFS|__GFP_NOFAIL), nodemask=0, order=0, oom_score_adj=0 kworker/u4:5 cpuset=/ mems_allowed=0 CPU: 1 PID: 2603 Comm: kworker/u4:5 Not tainted 4.9.0-gentoo #2 [...] Mem-Info: active_anon:58685 inactive_anon:90 isolated_anon:0 active_file:274324 inactive_file:281962 isolated_file:0 unevictable:0 dirty:649 writeback:0 unstable:0 slab_reclaimable:40662 slab_unreclaimable:17754 mapped:7382 shmem:202 pagetables:351 bounce:0 free:206736 free_pcp:332 free_cma:0 Node 0 active_anon:234740kB inactive_anon:360kB active_file:1097296kB inactive_file:1127848kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:29528kB dirty:2596kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 184320kB anon_thp: 808kB writeback_tmp:0kB unstable:0kB pages_scanned:0 all_unreclaimable? no DMA free:3952kB min:788kB low:984kB high:1180kB active_anon:0kB inactive_anon:0kB active_file:7316kB inactive_file:0kB unevictable:0kB writepending:96kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:3200kB slab_unreclaimable:1408kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 813 3474 3474 Normal free:41332kB min:41368kB low:51708kB high:62048kB active_anon:0kB inactive_anon:0kB active_file:532748kB inactive_file:44kB unevictable:0kB writepending:24kB present:897016kB managed:836248kB mlocked:0kB slab_reclaimable:159448kB slab_unreclaimable:69608kB kernel_stack:1112kB pagetables:1404kB bounce:0kB free_pcp:528kB local_pcp:340kB free_cma:0kB lowmem_reserve[]: 0 0 21292 21292 HighMem free:781660kB min:512kB low:34356kB high:68200kB active_anon:234740kB inactive_anon:360kB active_file:557232kB inactive_file:1127804kB unevictable:0kB writepending:2592kB present:2725384kB managed:2725384kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:800kB local_pcp:608kB free_cma:0kB the oom killer is clearly pre-mature because there there is still a lot of page cache in the zone Normal which should satisfy this lowmem request. Further debugging has shown that the reclaim cannot make any forward progress because the page cache is hidden in the active list which doesn't get rotated because inactive_list_is_low is not memcg aware. The code simply subtracts per-zone highmem counters from the respective memcg's lru sizes which doesn't make any sense. We can simply end up always seeing the resulting active and inactive counts 0 and return false. This issue is not limited to 32b kernels but in practice the effect on systems without CONFIG_HIGHMEM would be much harder to notice because we do not invoke the OOM killer for allocations requests targeting < ZONE_NORMAL. Fix the issue by tracking per zone lru page counts in mem_cgroup_per_node and subtract per-memcg highmem counts when memcg is enabled. Introduce helper lruvec_zone_lru_size which redirects to either zone counters or mem_cgroup_get_zone_lru_size when appropriate. We are losing empty LRU but non-zero lru size detection introduced by ca707239e8a7 ("mm: update_lru_size warn and reset bad lru_size") because of the inherent zone vs. node discrepancy. Fixes: f8d1a31163fc ("mm: consider whether to decivate based on eligible zones inactive ratio") Link: http://lkml.kernel.org/r/20170104100825.3729-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Nils Holland <nholland@tisys.org> Tested-by: Nils Holland <nholland@tisys.org> Reported-by: Klaus Ethgen <Klaus@Ethgen.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5f33a080 |
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12-Dec-2016 |
Shaohua Li <shli@fb.com> |
mm/vmscan.c: set correct defer count for shrinker Our system uses significantly more slab memory with memcg enabled with the latest kernel. With 3.10 kernel, slab uses 2G memory, while with 4.6 kernel, 6G memory is used. The shrinker has problem. Let's see we have two memcg for one shrinker. In do_shrink_slab: 1. Check cg1. nr_deferred = 0, assume total_scan = 700. batch size is 1024, then no memory is freed. nr_deferred = 700 2. Check cg2. nr_deferred = 700. Assume freeable = 20, then total_scan = 10 or 40. Let's assume it's 10. No memory is freed. nr_deferred = 10. The deferred share of cg1 is lost in this case. kswapd will free no memory even run above steps again and again. The fix makes sure one memcg's deferred share isn't lost. Link: http://lkml.kernel.org/r/2414be961b5d25892060315fbb56bb19d81d0c07.1476227351.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bd041733 |
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02-Dec-2016 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: add cond_resched() into shrink_node_memcg() Boris Zhmurov has reported RCU stalls during the kswapd reclaim: INFO: rcu_sched detected stalls on CPUs/tasks: 23-...: (22 ticks this GP) idle=92f/140000000000000/0 softirq=2638404/2638404 fqs=23 (detected by 4, t=6389 jiffies, g=786259, c=786258, q=42115) Task dump for CPU 23: kswapd1 R running task 0 148 2 0x00000008 Call Trace: shrink_node+0xd2/0x2f0 kswapd+0x2cb/0x6a0 mem_cgroup_shrink_node+0x160/0x160 kthread+0xbd/0xe0 __switch_to+0x1fa/0x5c0 ret_from_fork+0x1f/0x40 kthread_create_on_node+0x180/0x180 a closer code inspection has shown that we might indeed miss all the scheduling points in the reclaim path if no pages can be isolated from the LRU list. This is a pathological case but other reports from Donald Buczek have shown that we might indeed hit such a path: clusterd-989 [009] .... 118023.654491: mm_vmscan_direct_reclaim_end: nr_reclaimed=193 kswapd1-86 [001] dN.. 118023.987475: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239830 nr_taken=0 file=1 kswapd1-86 [001] dN.. 118024.320968: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239844 nr_taken=0 file=1 kswapd1-86 [001] dN.. 118024.654375: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239858 nr_taken=0 file=1 kswapd1-86 [001] dN.. 118024.987036: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239872 nr_taken=0 file=1 kswapd1-86 [001] dN.. 118025.319651: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239886 nr_taken=0 file=1 kswapd1-86 [001] dN.. 118025.652248: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239900 nr_taken=0 file=1 kswapd1-86 [001] dN.. 118025.984870: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239914 nr_taken=0 file=1 [...] kswapd1-86 [001] dN.. 118084.274403: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4241133 nr_taken=0 file=1 this is minute long snapshot which didn't take a single page from the LRU. It is not entirely clear why only 1303 pages have been scanned during that time (maybe there was a heavy IRQ activity interfering). In any case it looks like we can really hit long periods without scheduling on non preemptive kernels so an explicit cond_resched() in shrink_node_memcg which is independent on the reclaim operation is due. Link: http://lkml.kernel.org/r/20161202095841.16648-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Boris Zhmurov <bb@kernelpanic.ru> Tested-by: Boris Zhmurov <bb@kernelpanic.ru> Reported-by: Donald Buczek <buczek@molgen.mpg.de> Reported-by: "Christopher S. Aker" <caker@theshore.net> Reported-by: Paul Menzel <pmenzel@molgen.mpg.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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517bbed9 |
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03-Nov-2016 |
Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
mm/vmscan: Convert to hotplug state machine Install the callbacks via the state machine. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161103145021.28528-8-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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89a28483 |
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27-Oct-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: do not recurse in direct reclaim On 4.0, we saw a stack corruption from a page fault entering direct memory cgroup reclaim, calling into btrfs_releasepage(), which then tried to allocate an extent and recursed back into a kmem charge ad nauseam: [...] btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 memcg_charge_kmem+0x40/0x80 new_slab+0x2d9/0x5a0 __slab_alloc+0x2fd/0x44f kmem_cache_alloc+0x193/0x1e0 alloc_extent_state+0x21/0xc0 __clear_extent_bit+0x2b5/0x400 try_release_extent_mapping+0x1a3/0x220 __btrfs_releasepage+0x31/0x70 btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 mem_cgroup_try_charge+0x65/0x1c0 handle_mm_fault+0x117f/0x1510 __do_page_fault+0x177/0x420 do_page_fault+0xc/0x10 page_fault+0x22/0x30 On later kernels, kmem charging is opt-in rather than opt-out, and that particular kmem allocation in btrfs_releasepage() is no longer being charged and won't recurse and overrun the stack anymore. But it's not impossible for an accounted allocation to happen from the memcg direct reclaim context, and we needed to reproduce this crash many times before we even got a useful stack trace out of it. Like other direct reclaimers, mark tasks in memcg reclaim PF_MEMALLOC to avoid recursing into any other form of direct reclaim. Then let recursive charges from PF_MEMALLOC contexts bypass the cgroup limit. Link: http://lkml.kernel.org/r/20161025141050.GA13019@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c9634cf0 |
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07-Oct-2016 |
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> |
mm: use zonelist name instead of using hardcoded index Use the existing enums instead of hardcoded index when looking at the zonelist. This makes it more readable. No functionality change by this patch. Link: http://lkml.kernel.org/r/1472227078-24852-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bf484383 |
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07-Oct-2016 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: get rid of throttle_vm_writeout throttle_vm_writeout() was introduced back in 2005 to fix OOMs caused by excessive pageout activity during the reclaim. Too many pages could be put under writeback therefore LRUs would be full of unreclaimable pages until the IO completes and in turn the OOM killer could be invoked. There have been some important changes introduced since then in the reclaim path though. Writers are throttled by balance_dirty_pages when initiating the buffered IO and later during the memory pressure, the direct reclaim is throttled by wait_iff_congested if the node is considered congested by dirty pages on LRUs and the underlying bdi is congested by the queued IO. The kswapd is throttled as well if it encounters pages marked for immediate reclaim or under writeback which signals that that there are too many pages under writeback already. Finally should_reclaim_retry does congestion_wait if the reclaim cannot make any progress and there are too many dirty/writeback pages. Another important aspect is that we do not issue any IO from the direct reclaim context anymore. In a heavy parallel load this could queue a lot of IO which would be very scattered and thus unefficient which would just make the problem worse. This three mechanisms should throttle and keep the amount of IO in a steady state even under heavy IO and memory pressure so yet another throttling point doesn't really seem helpful. Quite contrary, Mikulas Patocka has reported that swap backed by dm-crypt doesn't work properly because the swapout IO cannot make sufficient progress as the writeout path depends on dm_crypt worker which has to allocate memory to perform the encryption. In order to guarantee a forward progress it relies on the mempool allocator. mempool_alloc(), however, prefers to use the underlying (usually page) allocator before it grabs objects from the pool. Such an allocation can dive into the memory reclaim and consequently to throttle_vm_writeout. If there are too many dirty or pages under writeback it will get throttled even though it is in fact a flusher to clear pending pages. kworker/u4:0 D ffff88003df7f438 10488 6 2 0x00000000 Workqueue: kcryptd kcryptd_crypt [dm_crypt] Call Trace: schedule+0x3c/0x90 schedule_timeout+0x1d8/0x360 io_schedule_timeout+0xa4/0x110 congestion_wait+0x86/0x1f0 throttle_vm_writeout+0x44/0xd0 shrink_zone_memcg+0x613/0x720 shrink_zone+0xe0/0x300 do_try_to_free_pages+0x1ad/0x450 try_to_free_pages+0xef/0x300 __alloc_pages_nodemask+0x879/0x1210 alloc_pages_current+0xa1/0x1f0 new_slab+0x2d7/0x6a0 ___slab_alloc+0x3fb/0x5c0 __slab_alloc+0x51/0x90 kmem_cache_alloc+0x27b/0x310 mempool_alloc_slab+0x1d/0x30 mempool_alloc+0x91/0x230 bio_alloc_bioset+0xbd/0x260 kcryptd_crypt+0x114/0x3b0 [dm_crypt] Let's just drop throttle_vm_writeout altogether. It is not very much helpful anymore. I have tried to test a potential writeback IO runaway similar to the one described in the original patch which has introduced that [1]. Small virtual machine (512MB RAM, 4 CPUs, 2G of swap space and disk image on a rather slow NFS in a sync mode on the host) with 8 parallel writers each writing 1G worth of data. As soon as the pagecache fills up and the direct reclaim hits then I start anon memory consumer in a loop (allocating 300M and exiting after populating it) in the background to make the memory pressure even stronger as well as to disrupt the steady state for the IO. The direct reclaim is throttled because of the congestion as well as kswapd hitting congestion_wait due to nr_immediate but throttle_vm_writeout doesn't ever trigger the sleep throughout the test. Dirty+writeback are close to nr_dirty_threshold with some fluctuations caused by the anon consumer. [1] https://www2.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc1/2.6.9-rc1-mm3/broken-out/vm-pageout-throttling.patch Link: http://lkml.kernel.org/r/1471171473-21418-1-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Mikulas Patocka <mpatocka@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: NeilBrown <neilb@suse.com> Cc: Ondrej Kozina <okozina@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fdd4c614 |
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07-Oct-2016 |
Vlastimil Babka <vbabka@suse.cz> |
mm, vmscan: make compaction_ready() more accurate and readable The compaction_ready() is used during direct reclaim for costly order allocations to skip reclaim for zones where compaction should be attempted instead. It's combining the standard compaction_suitable() check with its own watermark check based on high watermark with extra gap, and the result is confusing at best. This patch attempts to better structure and document the checks involved. First, compaction_suitable() can determine that the allocation should either succeed already, or that compaction doesn't have enough free pages to proceed. The third possibility is that compaction has enough free pages, but we still decide to reclaim first - unless we are already above the high watermark with gap. This does not mean that the reclaim will actually reach this watermark during single attempt, this is rather an over-reclaim protection. So document the code as such. The check for compaction_deferred() is removed completely, as it in fact had no proper role here. The result after this patch is mainly a less confusing code. We also skip some over-reclaim in cases where the allocation should already succed. Link: http://lkml.kernel.org/r/20160810091226.6709-12-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9861a62c |
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07-Oct-2016 |
Vlastimil Babka <vbabka@suse.cz> |
mm, compaction: create compact_gap wrapper Compaction uses a watermark gap of (2UL << order) pages at various places and it's not immediately obvious why. Abstract it through a compact_gap() wrapper to create a single place with a thorough explanation. [vbabka@suse.cz: clarify the comment of compact_gap()] Link: http://lkml.kernel.org/r/7b6aed1f-fdf8-2063-9ff4-bbe4de712d37@suse.cz Link: http://lkml.kernel.org/r/20160810091226.6709-9-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cf378319 |
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07-Oct-2016 |
Vlastimil Babka <vbabka@suse.cz> |
mm, compaction: rename COMPACT_PARTIAL to COMPACT_SUCCESS COMPACT_PARTIAL has historically meant that compaction returned after doing some work without fully compacting a zone. It however didn't distinguish if compaction terminated because it succeeded in creating the requested high-order page. This has changed recently and now we only return COMPACT_PARTIAL when compaction thinks it succeeded, or the high-order watermark check in compaction_suitable() passes and no compaction needs to be done. So at this point we can make the return value clearer by renaming it to COMPACT_SUCCESS. The next patch will remove some redundant tests for success where compaction just returned COMPACT_SUCCESS. Link: http://lkml.kernel.org/r/20160810091226.6709-4-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b385d21f |
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23-Sep-2016 |
Hugh Dickins <hughd@google.com> |
mm: delete unnecessary and unsafe init_tlb_ubc() init_tlb_ubc() looked unnecessary to me: tlb_ubc is statically initialized with zeroes in the init_task, and copied from parent to child while it is quiescent in arch_dup_task_struct(); so I went to delete it. But inserted temporary debug WARN_ONs in place of init_tlb_ubc() to check that it was always empty at that point, and found them firing: because memcg reclaim can recurse into global reclaim (when allocating biosets for swapout in my case), and arrive back at the init_tlb_ubc() in shrink_node_memcg(). Resetting tlb_ubc.flush_required at that point is wrong: if the upper level needs a deferred TLB flush, but the lower level turns out not to, we miss a TLB flush. But fortunately, that's the only part of the protocol that does not nest: with the initialization removed, cpumask collects bits from upper and lower levels, and flushes TLB when needed. Fixes: 72b252aed506 ("mm: send one IPI per CPU to TLB flush all entries after unmapping pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: stable@vger.kernel.org # 4.3+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6aa303de |
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01-Sep-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator Firmware Assisted Dump (FA_DUMP) on ppc64 reserves substantial amounts of memory when booting a secondary kernel. Srikar Dronamraju reported that multiple nodes may have no memory managed by the buddy allocator but still return true for populated_zone(). Commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes") was reported to cause kswapd to spin at 100% CPU usage when fadump was enabled. The old code happened to deal with the situation of a populated node with zero free pages by co-incidence but the current code tries to reclaim populated zones without realising that is impossible. We cannot just convert populated_zone() as many existing users really need to check for present_pages. This patch introduces a managed_zone() helper and uses it in the few cases where it is critical that the check is made for managed pages -- zonelist construction and page reclaim. Link: http://lkml.kernel.org/r/20160831195104.GB8119@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b5afba29 |
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02-Aug-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: fix memcg-aware shrinkers not called on global reclaim We must call shrink_slab() for each memory cgroup on both global and memcg reclaim in shrink_node_memcg(). Commit d71df22b55099 accidentally changed that so that now shrink_slab() is only called with memcg != NULL on memcg reclaim. As a result, memcg-aware shrinkers (including dentry/inode) are never invoked on global reclaim. Fix that. Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis") Link: http://lkml.kernel.org/r/1470056590-7177-1-git-send-email-vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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91dcade4 |
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28-Jul-2016 |
Minchan Kim <minchan@kernel.org> |
mm: bail out in shrink_inactive_list() With node-lru, if there are enough reclaimable pages in highmem but nothing in lowmem, VM can try to shrink inactive list although the requested zone is lowmem. The problem is that if the inactive list is full of highmem pages then a direct reclaimer searching for a lowmem page waste CPU scanning uselessly. It just burns out CPU. Even, many direct reclaimers are stalled by too_many_isolated if lots of parallel reclaimer are going on although there are no reclaimable memory in inactive list. I tried the experiment 4 times in 32bit 2G 8 CPU KVM machine to get elapsed time. hackbench 500 process 2 = Old = 1st: 289s 2nd: 310s 3rd: 112s 4th: 272s = Now = 1st: 31s 2nd: 132s 3rd: 162s 4th: 50s. [akpm@linux-foundation.org: fixes per Mel] Link: http://lkml.kernel.org/r/1469433119-1543-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d7f05528 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: account for skipped pages as a partial scan Page reclaim determines whether a pgdat is unreclaimable by examining how many pages have been scanned since a page was freed and comparing that to the LRU sizes. Skipped pages are not reclaim candidates but contribute to scanned. This can prematurely mark a pgdat as unreclaimable and trigger an OOM kill. This patch accounts for skipped pages as a partial scan so that an unreclaimable pgdat will still be marked as such but by scaling the cost of a skip, it'll avoid the pgdat being marked prematurely. Link: http://lkml.kernel.org/r/1469110261-7365-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f8d1a311 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: consider whether to decivate based on eligible zones inactive ratio Minchan Kim reported that with per-zone lru state it was possible to identify that a normal zone with 8^M anonymous pages could trigger OOM with non-atomic order-0 allocations as all pages in the zone were in the active list. gfp_mask=0x26004c0(GFP_KERNEL|__GFP_REPEAT|__GFP_NOTRACK), order=0 Call Trace: __alloc_pages_nodemask+0xe52/0xe60 ? new_slab+0x39c/0x3b0 new_slab+0x39c/0x3b0 ___slab_alloc.constprop.87+0x6da/0x840 ? __alloc_skb+0x3c/0x260 ? enqueue_task_fair+0x73/0xbf0 ? poll_select_copy_remaining+0x140/0x140 __slab_alloc.isra.81.constprop.86+0x40/0x6d ? __alloc_skb+0x3c/0x260 kmem_cache_alloc+0x22c/0x260 ? __alloc_skb+0x3c/0x260 __alloc_skb+0x3c/0x260 alloc_skb_with_frags+0x4e/0x1a0 sock_alloc_send_pskb+0x16a/0x1b0 ? wait_for_unix_gc+0x31/0x90 unix_stream_sendmsg+0x28d/0x340 sock_sendmsg+0x2d/0x40 sock_write_iter+0x6c/0xc0 __vfs_write+0xc0/0x120 vfs_write+0x9b/0x1a0 ? __might_fault+0x49/0xa0 SyS_write+0x44/0x90 do_fast_syscall_32+0xa6/0x1e0 Mem-Info: active_anon:101103 inactive_anon:102219 isolated_anon:0 active_file:503 inactive_file:544 isolated_file:0 unevictable:0 dirty:0 writeback:34 unstable:0 slab_reclaimable:6298 slab_unreclaimable:74669 mapped:863 shmem:0 pagetables:100998 bounce:0 free:23573 free_pcp:1861 free_cma:0 Node 0 active_anon:404412kB inactive_anon:409040kB active_file:2012kB inactive_file:2176kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:3452kB dirty:0kB writeback:136kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1320845 all_unreclaimable? yes DMA free:3296kB min:68kB low:84kB high:100kB active_anon:5540kB inactive_anon:0kB active_file:0kB inactive_file:0kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:248kB slab_unreclaimable:2628kB kernel_stack:792kB pagetables:2316kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 809 1965 1965 Normal free:3600kB min:3604kB low:4504kB high:5404kB active_anon:86304kB inactive_anon:0kB active_file:160kB inactive_file:376kB present:897016kB managed:858524kB mlocked:0kB slab_reclaimable:24944kB slab_unreclaimable:296048kB kernel_stack:163832kB pagetables:35892kB bounce:0kB free_pcp:3076kB local_pcp:656kB free_cma:0kB lowmem_reserve[]: 0 0 9247 9247 HighMem free:86156kB min:512kB low:1796kB high:3080kB active_anon:312852kB inactive_anon:410024kB active_file:1924kB inactive_file:2012kB present:1183736kB managed:1183736kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:365784kB bounce:0kB free_pcp:3868kB local_pcp:720kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 DMA: 8*4kB (UM) 8*8kB (UM) 4*16kB (M) 2*32kB (UM) 2*64kB (UM) 1*128kB (M) 3*256kB (UME) 2*512kB (UE) 1*1024kB (E) 0*2048kB 0*4096kB = 3296kB Normal: 240*4kB (UME) 160*8kB (UME) 23*16kB (ME) 3*32kB (UE) 3*64kB (UME) 2*128kB (ME) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3408kB HighMem: 10942*4kB (UM) 3102*8kB (UM) 866*16kB (UM) 76*32kB (UM) 11*64kB (UM) 4*128kB (UM) 1*256kB (M) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 86344kB Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB 54409 total pagecache pages 53215 pages in swap cache Swap cache stats: add 300982, delete 247765, find 157978/226539 Free swap = 3803244kB Total swap = 4192252kB 524186 pages RAM 295934 pages HighMem/MovableOnly 9642 pages reserved 0 pages cma reserved The problem is due to the active deactivation logic in inactive_list_is_low: Node 0 active_anon:404412kB inactive_anon:409040kB IOW, (inactive_anon of node * inactive_ratio > active_anon of node) due to highmem anonymous stat so VM never deactivates normal zone's anonymous pages. This patch is a modified version of Minchan's original solution but based upon it. The problem with Minchan's patch is that any low zone with an imbalanced list could force a rotation. In this patch, a zone-constrained global reclaim will rotate the list if the inactive/active ratio of all eligible zones needs to be corrected. It is possible that higher zone pages will be initially rotated prematurely but this is the safer choice to maintain overall LRU age. Link: http://lkml.kernel.org/r/20160722090929.GJ10438@techsingularity.net Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5a1c84b4 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: remove reclaim and compaction retry approximations If per-zone LRU accounting is available then there is no point approximating whether reclaim and compaction should retry based on pgdat statistics. This is effectively a revert of "mm, vmstat: remove zone and node double accounting by approximating retries" with the difference that inactive/active stats are still available. This preserves the history of why the approximation was retried and why it had to be reverted to handle OOM kills on 32-bit systems. Link: http://lkml.kernel.org/r/1469110261-7365-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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71c799f4 |
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28-Jul-2016 |
Minchan Kim <minchan@kernel.org> |
mm: add per-zone lru list stat When I did stress test with hackbench, I got OOM message frequently which didn't ever happen in zone-lru. gfp_mask=0x26004c0(GFP_KERNEL|__GFP_REPEAT|__GFP_NOTRACK), order=0 .. .. __alloc_pages_nodemask+0xe52/0xe60 ? new_slab+0x39c/0x3b0 new_slab+0x39c/0x3b0 ___slab_alloc.constprop.87+0x6da/0x840 ? __alloc_skb+0x3c/0x260 ? _raw_spin_unlock_irq+0x27/0x60 ? trace_hardirqs_on_caller+0xec/0x1b0 ? finish_task_switch+0xa6/0x220 ? poll_select_copy_remaining+0x140/0x140 __slab_alloc.isra.81.constprop.86+0x40/0x6d ? __alloc_skb+0x3c/0x260 kmem_cache_alloc+0x22c/0x260 ? __alloc_skb+0x3c/0x260 __alloc_skb+0x3c/0x260 alloc_skb_with_frags+0x4e/0x1a0 sock_alloc_send_pskb+0x16a/0x1b0 ? wait_for_unix_gc+0x31/0x90 ? alloc_set_pte+0x2ad/0x310 unix_stream_sendmsg+0x28d/0x340 sock_sendmsg+0x2d/0x40 sock_write_iter+0x6c/0xc0 __vfs_write+0xc0/0x120 vfs_write+0x9b/0x1a0 ? __might_fault+0x49/0xa0 SyS_write+0x44/0x90 do_fast_syscall_32+0xa6/0x1e0 sysenter_past_esp+0x45/0x74 Mem-Info: active_anon:104698 inactive_anon:105791 isolated_anon:192 active_file:433 inactive_file:283 isolated_file:22 unevictable:0 dirty:0 writeback:296 unstable:0 slab_reclaimable:6389 slab_unreclaimable:78927 mapped:474 shmem:0 pagetables:101426 bounce:0 free:10518 free_pcp:334 free_cma:0 Node 0 active_anon:418792kB inactive_anon:423164kB active_file:1732kB inactive_file:1132kB unevictable:0kB isolated(anon):768kB isolated(file):88kB mapped:1896kB dirty:0kB writeback:1184kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1478632 all_unreclaimable? yes DMA free:3304kB min:68kB low:84kB high:100kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:4088kB kernel_stack:0kB pagetables:2480kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 809 1965 1965 Normal free:3436kB min:3604kB low:4504kB high:5404kB present:897016kB managed:858460kB mlocked:0kB slab_reclaimable:25556kB slab_unreclaimable:311712kB kernel_stack:164608kB pagetables:30844kB bounce:0kB free_pcp:620kB local_pcp:104kB free_cma:0kB lowmem_reserve[]: 0 0 9247 9247 HighMem free:33808kB min:512kB low:1796kB high:3080kB present:1183736kB managed:1183736kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:372252kB bounce:0kB free_pcp:428kB local_pcp:72kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 DMA: 2*4kB (UM) 2*8kB (UM) 0*16kB 1*32kB (U) 1*64kB (U) 2*128kB (UM) 1*256kB (U) 1*512kB (M) 0*1024kB 1*2048kB (U) 0*4096kB = 3192kB Normal: 33*4kB (MH) 79*8kB (ME) 11*16kB (M) 4*32kB (M) 2*64kB (ME) 2*128kB (EH) 7*256kB (EH) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3244kB HighMem: 2590*4kB (UM) 1568*8kB (UM) 491*16kB (UM) 60*32kB (UM) 6*64kB (M) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 33064kB Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB 25121 total pagecache pages 24160 pages in swap cache Swap cache stats: add 86371, delete 62211, find 42865/60187 Free swap = 4015560kB Total swap = 4192252kB 524186 pages RAM 295934 pages HighMem/MovableOnly 9658 pages reserved 0 pages cma reserved The order-0 allocation for normal zone failed while there are a lot of reclaimable memory(i.e., anonymous memory with free swap). I wanted to analyze the problem but it was hard because we removed per-zone lru stat so I couldn't know how many of anonymous memory there are in normal/dma zone. When we investigate OOM problem, reclaimable memory count is crucial stat to find a problem. Without it, it's hard to parse the OOM message so I believe we should keep it. With per-zone lru stat, gfp_mask=0x26004c0(GFP_KERNEL|__GFP_REPEAT|__GFP_NOTRACK), order=0 Mem-Info: active_anon:101103 inactive_anon:102219 isolated_anon:0 active_file:503 inactive_file:544 isolated_file:0 unevictable:0 dirty:0 writeback:34 unstable:0 slab_reclaimable:6298 slab_unreclaimable:74669 mapped:863 shmem:0 pagetables:100998 bounce:0 free:23573 free_pcp:1861 free_cma:0 Node 0 active_anon:404412kB inactive_anon:409040kB active_file:2012kB inactive_file:2176kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:3452kB dirty:0kB writeback:136kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1320845 all_unreclaimable? yes DMA free:3296kB min:68kB low:84kB high:100kB active_anon:5540kB inactive_anon:0kB active_file:0kB inactive_file:0kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:248kB slab_unreclaimable:2628kB kernel_stack:792kB pagetables:2316kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 809 1965 1965 Normal free:3600kB min:3604kB low:4504kB high:5404kB active_anon:86304kB inactive_anon:0kB active_file:160kB inactive_file:376kB present:897016kB managed:858524kB mlocked:0kB slab_reclaimable:24944kB slab_unreclaimable:296048kB kernel_stack:163832kB pagetables:35892kB bounce:0kB free_pcp:3076kB local_pcp:656kB free_cma:0kB lowmem_reserve[]: 0 0 9247 9247 HighMem free:86156kB min:512kB low:1796kB high:3080kB active_anon:312852kB inactive_anon:410024kB active_file:1924kB inactive_file:2012kB present:1183736kB managed:1183736kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:365784kB bounce:0kB free_pcp:3868kB local_pcp:720kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 DMA: 8*4kB (UM) 8*8kB (UM) 4*16kB (M) 2*32kB (UM) 2*64kB (UM) 1*128kB (M) 3*256kB (UME) 2*512kB (UE) 1*1024kB (E) 0*2048kB 0*4096kB = 3296kB Normal: 240*4kB (UME) 160*8kB (UME) 23*16kB (ME) 3*32kB (UE) 3*64kB (UME) 2*128kB (ME) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3408kB HighMem: 10942*4kB (UM) 3102*8kB (UM) 866*16kB (UM) 76*32kB (UM) 11*64kB (UM) 4*128kB (UM) 1*256kB (M) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 86344kB Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB 54409 total pagecache pages 53215 pages in swap cache Swap cache stats: add 300982, delete 247765, find 157978/226539 Free swap = 3803244kB Total swap = 4192252kB 524186 pages RAM 295934 pages HighMem/MovableOnly 9642 pages reserved 0 pages cma reserved With that, we can see normal zone has a 86M reclaimable memory so we can know something goes wrong(I will fix the problem in next patch) in reclaim. [mgorman@techsingularity.net: rename zone LRU stats in /proc/vmstat] Link: http://lkml.kernel.org/r/20160725072300.GK10438@techsingularity.net Link: http://lkml.kernel.org/r/1469110261-7365-2-git-send-email-mgorman@techsingularity.net Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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785b99fe |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: release/reacquire lru_lock on pgdat change With node-lru, the locking is based on the pgdat. As Minchan pointed out, there is an opportunity to reduce LRU lock release/acquire in check_move_unevictable_pages by only changing lock on a pgdat change. [mgorman@techsingularity.net: remove double initialisation] Link: http://lkml.kernel.org/r/20160719074835.GC10438@techsingularity.net Link: http://lkml.kernel.org/r/1468853426-12858-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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22fecdf5 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: remove redundant check in shrink_zones() As pointed out by Minchan Kim, shrink_zones() checks for populated zones in a zonelist but a zonelist can never contain unpopulated zones. While it's not related to the node-lru series, it can be cleaned up now. Link: http://lkml.kernel.org/r/1468853426-12858-2-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Suggested-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7ee36a14 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: Update all zone LRU sizes before updating memcg Minchan Kim reported setting the following warning on a 32-bit system although it can affect 64-bit systems. WARNING: CPU: 4 PID: 1322 at mm/memcontrol.c:998 mem_cgroup_update_lru_size+0x103/0x110 mem_cgroup_update_lru_size(f44b4000, 1, -7): zid 1 lru_size 1 but empty Modules linked in: CPU: 4 PID: 1322 Comm: cp Not tainted 4.7.0-rc4-mm1+ #143 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x76/0xaf __warn+0xea/0x110 ? mem_cgroup_update_lru_size+0x103/0x110 warn_slowpath_fmt+0x3b/0x40 mem_cgroup_update_lru_size+0x103/0x110 isolate_lru_pages.isra.61+0x2e2/0x360 shrink_active_list+0xac/0x2a0 ? __delay+0xe/0x10 shrink_node_memcg+0x53c/0x7a0 shrink_node+0xab/0x2a0 do_try_to_free_pages+0xc6/0x390 try_to_free_pages+0x245/0x590 LRU list contents and counts are updated separately. Counts are updated before pages are added to the LRU and updated after pages are removed. The warning above is from a check in mem_cgroup_update_lru_size that ensures that list sizes of zero are empty. The problem is that node-lru needs to account for highmem pages if CONFIG_HIGHMEM is set. One impact of the implementation is that the sizes are updated in multiple passes when pages from multiple zones were isolated. This happens whether HIGHMEM is set or not. When multiple zones are isolated, it's possible for a debugging check in memcg to be tripped. This patch forces all the zone counts to be updated before the memcg function is called. Link: http://lkml.kernel.org/r/1468588165-12461-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Tested-by: Minchan Kim <minchan@kernel.org> Reported-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bca67592 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmstat: remove zone and node double accounting by approximating retries The number of LRU pages, dirty pages and writeback pages must be accounted for on both zones and nodes because of the reclaim retry logic, compaction retry logic and highmem calculations all depending on per-zone stats. Many lowmem allocations are immune from OOM kill due to a check in __alloc_pages_may_oom for (ac->high_zoneidx < ZONE_NORMAL) since commit 03668b3ceb0c ("oom: avoid oom killer for lowmem allocations"). The exception is costly high-order allocations or allocations that cannot fail. If the __alloc_pages_may_oom avoids OOM-kill for low-order lowmem allocations then it would fall through to __alloc_pages_direct_compact. This patch will blindly retry reclaim for zone-constrained allocations in should_reclaim_retry up to MAX_RECLAIM_RETRIES. This is not ideal but without per-zone stats there are not many alternatives. The impact it that zone-constrained allocations may delay before considering the OOM killer. As there is no guarantee enough memory can ever be freed to satisfy compaction, this patch avoids retrying compaction for zone-contrained allocations. In combination, that means that the per-node stats can be used when deciding whether to continue reclaim using a rough approximation. While it is possible this will make the wrong decision on occasion, it will not infinite loop as the number of reclaim attempts is capped by MAX_RECLAIM_RETRIES. The final step is calculating the number of dirtyable highmem pages. As those calculations only care about the global count of file pages in highmem. This patch uses a global counter used instead of per-zone stats as it is sufficient. In combination, this allows the per-zone LRU and dirty state counters to be removed. [mgorman@techsingularity.net: fix acct_highmem_file_pages()] Link: http://lkml.kernel.org/r/1468853426-12858-4-git-send-email-mgorman@techsingularity.netLink: http://lkml.kernel.org/r/1467970510-21195-35-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Suggested by: Michal Hocko <mhocko@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7cc30fcf |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: vmstat: account per-zone stalls and pages skipped during reclaim The vmstat allocstall was fairly useful in the general sense but node-based LRUs change that. It's important to know if a stall was for an address-limited allocation request as this will require skipping pages from other zones. This patch adds pgstall_* counters to replace allocstall. The sum of the counters will equal the old allocstall so it can be trivially recalculated. A high number of address-limited allocation requests may result in a lot of useless LRU scanning for suitable pages. As address-limited allocations require pages to be skipped, it's important to know how much useless LRU scanning took place so this patch adds pgskip* counters. This yields the following model 1. The number of address-space limited stalls can be accounted for (pgstall) 2. The amount of useless work required to reclaim the data is accounted (pgskip) 3. The total number of scans is available from pgscan_kswapd and pgscan_direct so from that the ratio of useful to useless scans can be calculated. [mgorman@techsingularity.net: s/pgstall/allocstall/] Link: http://lkml.kernel.org/r/1468404004-5085-3-git-send-email-mgorman@techsingularity.netLink: http://lkml.kernel.org/r/1467970510-21195-33-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e5146b12 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: add classzone information to tracepoints This is convenient when tracking down why the skip count is high because it'll show what classzone kswapd woke up at and what zones are being isolated. Link: http://lkml.kernel.org/r/1467970510-21195-29-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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84c7a777 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit The buffer_heads_over_limit limit in kswapd is inconsistent with direct reclaim behaviour. It may force an an attempt to reclaim from all zones and then not reclaim at all because higher zones were balanced than required by the original request. This patch will causes kswapd to consider reclaiming from all zones if buffer_heads_over_limit. However, if there are eligible zones for the allocation request that woke kswapd then no reclaim will occur even if buffer_heads_over_limit. This avoids kswapd over-reclaiming just because buffer_heads_over_limit. [mgorman@techsingularity.net: fix comment about buffer_heads_over_limit] Link: http://lkml.kernel.org/r/1468404004-5085-2-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-28-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d9f21d42 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: avoid passing in `remaining' unnecessarily to prepare_kswapd_sleep() As pointed out by Minchan Kim, the first call to prepare_kswapd_sleep() always passes in 0 for `remaining' and the second call can trivially check the parameter in advance. Suggested-by: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1467970510-21195-27-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4f588331 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready The scan_control structure has enough information available for compaction_ready() to make a decision. The classzone_idx manipulations in shrink_zones() are no longer necessary as the highest populated zone is no longer used to determine if shrink_slab should be called or not. [mgorman@techsingularity.net remove redundant check in shrink_zones()] Link: http://lkml.kernel.org/r/1468588165-12461-3-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-26-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
970a39a3 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: avoid passing in classzone_idx unnecessarily to shrink_node shrink_node receives all information it needs about classzone_idx from sc->reclaim_idx so remove the aliases. Link: http://lkml.kernel.org/r/1467970510-21195-25-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a5f5f91d |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: convert zone_reclaim to node_reclaim As reclaim is now per-node based, convert zone_reclaim to be node_reclaim. It is possible that a node will be reclaimed multiple times if it has multiple zones but this is unavoidable without caching all nodes traversed so far. The documentation and interface to userspace is the same from a configuration perspective and will will be similar in behaviour unless the node-local allocation requests were also limited to lower zones. Link: http://lkml.kernel.org/r/1467970510-21195-24-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e1a55637 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: only wakeup kswapd once per node for the requested classzone kswapd is woken when zones are below the low watermark but the wakeup decision is not taking the classzone into account. Now that reclaim is node-based, it is only required to wake kswapd once per node and only if all zones are unbalanced for the requested classzone. Note that one node might be checked multiple times if the zonelist is ordered by node because there is no cheap way of tracking what nodes have already been visited. For zone-ordering, each node should be checked only once. Link: http://lkml.kernel.org/r/1467970510-21195-22-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c4a25635 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: move vmscan writes and file write accounting to the node As reclaim is now node-based, it follows that page write activity due to page reclaim should also be accounted for on the node. For consistency, also account page writes and page dirtying on a per-node basis. After this patch, there are a few remaining zone counters that may appear strange but are fine. NUMA stats are still per-zone as this is a user-space interface that tools consume. NR_MLOCK, NR_SLAB_*, NR_PAGETABLE, NR_KERNEL_STACK and NR_BOUNCE are all allocations that potentially pin low memory and cannot trivially be reclaimed on demand. This information is still useful for debugging a page allocation failure warning. Link: http://lkml.kernel.org/r/1467970510-21195-21-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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11fb9989 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: move most file-based accounting to the node There are now a number of accounting oddities such as mapped file pages being accounted for on the node while the total number of file pages are accounted on the zone. This can be coped with to some extent but it's confusing so this patch moves the relevant file-based accounted. Due to throttling logic in the page allocator for reliable OOM detection, it is still necessary to track dirty and writeback pages on a per-zone basis. [mgorman@techsingularity.net: fix NR_ZONE_WRITE_PENDING accounting] Link: http://lkml.kernel.org/r/1468404004-5085-5-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-20-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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50658e2e |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: move page mapped accounting to the node Reclaim makes decisions based on the number of pages that are mapped but it's mixing node and zone information. Account NR_FILE_MAPPED and NR_ANON_PAGES pages on the node. Link: http://lkml.kernel.org/r/1467970510-21195-18-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ef8f2327 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, memcg: move memcg limit enforcement from zones to nodes Memcg needs adjustment after moving LRUs to the node. Limits are tracked per memcg but the soft-limit excess is tracked per zone. As global page reclaim is based on the node, it is easy to imagine a situation where a zone soft limit is exceeded even though the memcg limit is fine. This patch moves the soft limit tree the node. Technically, all the variable names should also change but people are already familiar by the meaning of "mz" even if "mn" would be a more appropriate name now. Link: http://lkml.kernel.org/r/1467970510-21195-15-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a9dd0a83 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: make shrink_node decisions more node-centric Earlier patches focused on having direct reclaim and kswapd use data that is node-centric for reclaiming but shrink_node() itself still uses too much zone information. This patch removes unnecessary zone-based information with the most important decision being whether to continue reclaim or not. Some memcg APIs are adjusted as a result even though memcg itself still uses some zone information. [mgorman@techsingularity.net: optimization] Link: http://lkml.kernel.org/r/1468588165-12461-2-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-14-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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86c79f6b |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: vmscan: do not reclaim from kswapd if there is any eligible zone kswapd scans from highest to lowest for a zone that requires balancing. This was necessary when reclaim was per-zone to fairly age pages on lower zones. Now that we are reclaiming on a per-node basis, any eligible zone can be used and pages will still be aged fairly. This patch avoids reclaiming excessively unless buffer_heads are over the limit and it's necessary to reclaim from a higher zone than requested by the waker of kswapd to relieve low memory pressure. [hillf.zj@alibaba-inc.com: Force kswapd reclaim no more than needed] Link: http://lkml.kernel.org/r/1466518566-30034-12-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-13-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6256c6b4 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: remove duplicate logic clearing node congestion and dirty state Reclaim may stall if there is too much dirty or congested data on a node. This was previously based on zone flags and the logic for clearing the flags is in two places. As congestion/dirty tracking is now tracked on a per-node basis, we can remove some duplicate logic. Link: http://lkml.kernel.org/r/1467970510-21195-12-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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79dafcdc |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: by default have direct reclaim only shrink once per node Direct reclaim iterates over all zones in the zonelist and shrinking them but this is in conflict with node-based reclaim. In the default case, only shrink once per node. Link: http://lkml.kernel.org/r/1467970510-21195-11-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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38087d9b |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: simplify the logic deciding whether kswapd sleeps kswapd goes through some complex steps trying to figure out if it should stay awake based on the classzone_idx and the requested order. It is unnecessarily complex and passes in an invalid classzone_idx to balance_pgdat(). What matters most of all is whether a larger order has been requsted and whether kswapd successfully reclaimed at the previous order. This patch irons out the logic to check just that and the end result is less headache inducing. Link: http://lkml.kernel.org/r/1467970510-21195-10-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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31483b6a |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: remove balance gap The balance gap was introduced to apply equal pressure to all zones when reclaiming for a higher zone. With node-based LRU, the need for the balance gap is removed and the code is dead so remove it. [vbabka@suse.cz: Also remove KSWAPD_ZONE_BALANCE_GAP_RATIO] Link: http://lkml.kernel.org/r/1467970510-21195-9-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1d82de61 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: make kswapd reclaim in terms of nodes Patch "mm: vmscan: Begin reclaiming pages on a per-node basis" started thinking of reclaim in terms of nodes but kswapd is still zone-centric. This patch gets rid of many of the node-based versus zone-based decisions. o A node is considered balanced when any eligible lower zone is balanced. This eliminates one class of age-inversion problem because we avoid reclaiming a newer page just because it's in the wrong zone o pgdat_balanced disappears because we now only care about one zone being balanced. o Some anomalies related to writeback and congestion tracking being based on zones disappear. o kswapd no longer has to take care to reclaim zones in the reverse order that the page allocator uses. o Most importantly of all, reclaim from node 0 with multiple zones will have similar aging and reclaiming characteristics as every other node. Link: http://lkml.kernel.org/r/1467970510-21195-8-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f7b60926 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: have kswapd only scan based on the highest requested zone kswapd checks all eligible zones to see if they need balancing even if it was woken for a lower zone. This made sense when we reclaimed on a per-zone basis because we wanted to shrink zones fairly so avoid age-inversion problems. Ideally this is completely unnecessary when reclaiming on a per-node basis. In theory, there may still be anomalies when all requests are for lower zones and very old pages are preserved in higher zones but this should be the exceptional case. Link: http://lkml.kernel.org/r/1467970510-21195-7-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b2e18757 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: begin reclaiming pages on a per-node basis This patch makes reclaim decisions on a per-node basis. A reclaimer knows what zone is required by the allocation request and skips pages from higher zones. In many cases this will be ok because it's a GFP_HIGHMEM request of some description. On 64-bit, ZONE_DMA32 requests will cause some problems but 32-bit devices on 64-bit platforms are increasingly rare. Historically it would have been a major problem on 32-bit with big Highmem:Lowmem ratios but such configurations are also now rare and even where they exist, they are not encouraged. If it really becomes a problem, it'll manifest as very low reclaim efficiencies. Link: http://lkml.kernel.org/r/1467970510-21195-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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599d0c95 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: move LRU lists to node This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a52633d8 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: move lru_lock to the node Node-based reclaim requires node-based LRUs and locking. This is a preparation patch that just moves the lru_lock to the node so later patches are easier to review. It is a mechanical change but note this patch makes contention worse because the LRU lock is hotter and direct reclaim and kswapd can contend on the same lock even when reclaiming from different zones. Link: http://lkml.kernel.org/r/1467970510-21195-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7751b2da |
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26-Jul-2016 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
vmscan: split file huge pages before paging them out This is preparation of vmscan for file huge pages. We cannot write out huge pages, so we need to split them on the way out. Link: http://lkml.kernel.org/r/1466021202-61880-22-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b1123ea6 |
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26-Jul-2016 |
Minchan Kim <minchan@kernel.org> |
mm: balloon: use general non-lru movable page feature Now, VM has a feature to migrate non-lru movable pages so balloon doesn't need custom migration hooks in migrate.c and compaction.c. Instead, this patch implements the page->mapping->a_ops-> {isolate|migrate|putback} functions. With that, we could remove hooks for ballooning in general migration functions and make balloon compaction simple. [akpm@linux-foundation.org: compaction.h requires that the includer first include node.h] Link: http://lkml.kernel.org/r/1464736881-24886-4-git-send-email-minchan@kernel.org Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Rafael Aquini <aquini@redhat.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0a0337e0 |
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20-May-2016 |
Michal Hocko <mhocko@suse.com> |
mm, oom: rework oom detection __alloc_pages_slowpath has traditionally relied on the direct reclaim and did_some_progress as an indicator that it makes sense to retry allocation rather than declaring OOM. shrink_zones had to rely on zone_reclaimable if shrink_zone didn't make any progress to prevent from a premature OOM killer invocation - the LRU might be full of dirty or writeback pages and direct reclaim cannot clean those up. zone_reclaimable allows to rescan the reclaimable lists several times and restart if a page is freed. This is really subtle behavior and it might lead to a livelock when a single freed page keeps allocator looping but the current task will not be able to allocate that single page. OOM killer would be more appropriate than looping without any progress for unbounded amount of time. This patch changes OOM detection logic and pulls it out from shrink_zone which is too low to be appropriate for any high level decisions such as OOM which is per zonelist property. It is __alloc_pages_slowpath which knows how many attempts have been done and what was the progress so far therefore it is more appropriate to implement this logic. The new heuristic is implemented in should_reclaim_retry helper called from __alloc_pages_slowpath. It tries to be more deterministic and easier to follow. It builds on an assumption that retrying makes sense only if the currently reclaimable memory + free pages would allow the current allocation request to succeed (as per __zone_watermark_ok) at least for one zone in the usable zonelist. This alone wouldn't be sufficient, though, because the writeback might get stuck and reclaimable pages might be pinned for a really long time or even depend on the current allocation context. Therefore there is a backoff mechanism implemented which reduces the reclaim target after each reclaim round without any progress. This means that we should eventually converge to only NR_FREE_PAGES as the target and fail on the wmark check and proceed to OOM. The backoff is simple and linear with 1/16 of the reclaimable pages for each round without any progress. We are optimistic and reset counter for successful reclaim rounds. Costly high order pages mostly preserve their semantic and those without __GFP_REPEAT fail right away while those which have the flag set will back off after the amount of reclaimable pages reaches equivalent of the requested order. The only difference is that if there was no progress during the reclaim we rely on zone watermark check. This is more logical thing to do than previous 1<<order attempts which were a result of zone_reclaimable faking the progress. [vdavydov@virtuozzo.com: check classzone_idx for shrink_zone] [hannes@cmpxchg.org: separate the heuristic into should_reclaim_retry] [rientjes@google.com: use zone_page_state_snapshot for NR_FREE_PAGES] [rientjes@google.com: shrink_zones doesn't need to return anything] Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b6459cc1 |
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20-May-2016 |
Michal Hocko <mhocko@suse.com> |
vmscan: consider classzone_idx in compaction_ready Motivation: As pointed out by Linus [2][3] relying on zone_reclaimable as a way to communicate the reclaim progress is rater dubious. I tend to agree, not only it is really obscure, it is not hard to imagine cases where a single page freed in the loop keeps all the reclaimers looping without getting any progress because their gfp_mask wouldn't allow to get that page anyway (e.g. single GFP_ATOMIC alloc and free loop). This is rather rare so it doesn't happen in the practice but the current logic which we have is rather obscure and hard to follow a also non-deterministic. This is an attempt to make the OOM detection more deterministic and easier to follow because each reclaimer basically tracks its own progress which is implemented at the page allocator layer rather spread out between the allocator and the reclaim. The more on the implementation is described in the first patch. I have tested several different scenarios but it should be clear that testing OOM killer is quite hard to be representative. There is usually a tiny gap between almost OOM and full blown OOM which is often time sensitive. Anyway, I have tested the following 2 scenarios and I would appreciate if there are more to test. Testing environment: a virtual machine with 2G of RAM and 2CPUs without any swap to make the OOM more deterministic. 1) 2 writers (each doing dd with 4M blocks to an xfs partition with 1G file size, removes the files and starts over again) running in parallel for 10s to build up a lot of dirty pages when 100 parallel mem_eaters (anon private populated mmap which waits until it gets signal) with 80M each. This causes an OOM flood of course and I have compared both patched and unpatched kernels. The test is considered finished after there are no OOM conditions detected. This should tell us whether there are any excessive kills or some of them premature (e.g. due to dirty pages): I have performed two runs this time each after a fresh boot. * base kernel $ grep "Out of memory:" base-oom-run1.log | wc -l 78 $ grep "Out of memory:" base-oom-run2.log | wc -l 78 $ grep "Kill process" base-oom-run1.log | tail -n1 [ 91.391203] Out of memory: Kill process 3061 (mem_eater) score 39 or sacrifice child $ grep "Kill process" base-oom-run2.log | tail -n1 [ 82.141919] Out of memory: Kill process 3086 (mem_eater) score 39 or sacrifice child $ grep "DMA32 free:" base-oom-run1.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk min: 5376.00 max: 6776.00 avg: 5530.75 std: 166.50 nr: 61 $ grep "DMA32 free:" base-oom-run2.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk min: 5416.00 max: 5608.00 avg: 5514.15 std: 42.94 nr: 52 $ grep "DMA32.*all_unreclaimable? no" base-oom-run1.log | wc -l 1 $ grep "DMA32.*all_unreclaimable? no" base-oom-run2.log | wc -l 3 * patched kernel $ grep "Out of memory:" patched-oom-run1.log | wc -l 78 miso@tiehlicka /mnt/share/devel/miso/kvm $ grep "Out of memory:" patched-oom-run2.log | wc -l 77 e grep "Kill process" patched-oom-run1.log | tail -n1 [ 497.317732] Out of memory: Kill process 3108 (mem_eater) score 39 or sacrifice child $ grep "Kill process" patched-oom-run2.log | tail -n1 [ 316.169920] Out of memory: Kill process 3093 (mem_eater) score 39 or sacrifice child $ grep "DMA32 free:" patched-oom-run1.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk min: 5420.00 max: 5808.00 avg: 5513.90 std: 60.45 nr: 78 $ grep "DMA32 free:" patched-oom-run2.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk min: 5380.00 max: 6384.00 avg: 5520.94 std: 136.84 nr: 77 e grep "DMA32.*all_unreclaimable? no" patched-oom-run1.log | wc -l 2 $ grep "DMA32.*all_unreclaimable? no" patched-oom-run2.log | wc -l 3 The patched kernel run noticeably longer while invoking OOM killer same number of times. This means that the original implementation is much more aggressive and triggers the OOM killer sooner. free pages stats show that neither kernels went OOM too early most of the time, though. I guess the difference is in the backoff when retries without any progress do sleep for a while if there is memory under writeback or dirty which is highly likely considering the parallel IO. Both kernels have seen races where zone wasn't marked unreclaimable and we still hit the OOM killer. This is most likely a race where a task managed to exit between the last allocation attempt and the oom killer invocation. 2) 2 writers again with 10s of run and then 10 mem_eaters to consume as much memory as possible without triggering the OOM killer. This required a lot of tuning but I've considered 3 consecutive runs in three different boots without OOM as a success. * base kernel size=$(awk '/MemFree/{printf "%dK", ($2/10)-(16*1024)}' /proc/meminfo) * patched kernel size=$(awk '/MemFree/{printf "%dK", ($2/10)-(12*1024)}' /proc/meminfo) That means 40M more memory was usable without triggering OOM killer. The base kernel sometimes managed to handle the same as patched but it wasn't consistent and failed in at least on of the 3 runs. This seems like a minor improvement. I was testing also GPF_REPEAT costly requests (hughetlb) with fragmented memory and under memory pressure. The results are in patch 11 where the logic is implemented. In short I can see huge improvement there. I am certainly interested in other usecases as well as well as any feedback. Especially those which require higher order requests. This patch (of 14): While playing with the oom detection rework [1] I have noticed that my heavy order-9 (hugetlb) load close to OOM ended up in an endless loop where the reclaim hasn't made any progress but did_some_progress didn't reflect that and compaction_suitable was backing off because no zone is above low wmark + 1 << order. It turned out that this is in fact an old standing bug in compaction_ready which ignores the requested_highidx and did the watermark check for 0 classzone_idx. This succeeds for zone DMA most of the time as the zone is mostly unused because of lowmem protection. As a result costly high order allocatios always report a successfull progress even when there was none. This wasn't a problem so far because these allocations usually fail quite early or retry only few times with __GFP_REPEAT but this will change after later patch in this series so make sure to not lie about the progress and propagate requested_highidx down to compaction_ready and use it for both the watermak check and compaction_suitable to fix this issue. [1] http://lkml.kernel.org/r/1459855533-4600-1-git-send-email-mhocko@kernel.org [2] https://lkml.org/lkml/2015/10/12/808 [3] https://lkml.org/lkml/2015/10/13/597 Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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59dc76b0 |
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20-May-2016 |
Rik van Riel <riel@redhat.com> |
mm: vmscan: reduce size of inactive file list The inactive file list should still be large enough to contain readahead windows and freshly written file data, but it no longer is the only source for detecting multiple accesses to file pages. The workingset refault measurement code causes recently evicted file pages that get accessed again after a shorter interval to be promoted directly to the active list. With that mechanism in place, we can afford to (on a larger system) dedicate more memory to the active file list, so we can actually cache more of the frequently used file pages in memory, and not have them pushed out by streaming writes, once-used streaming file reads, etc. This can help things like database workloads, where only half the page cache can currently be used to cache the database working set. This patch automatically increases that fraction on larger systems, using the same ratio that has already been used for anonymous memory. [hannes@cmpxchg.org: cgroup-awareness] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Andres Freund <andres@anarazel.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9d5e6a9f |
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19-May-2016 |
Hugh Dickins <hughd@google.com> |
mm: update_lru_size do the __mod_zone_page_state Konstantin Khlebnikov pointed out (nearly four years ago, when lumpy reclaim was removed) that lru_size can be updated by -nr_taken once per call to isolate_lru_pages(), instead of page by page. Update it inside isolate_lru_pages(), or at its two callsites? I chose to update it at the callsites, rearranging and grouping the updates by nr_taken and nr_scanned together in both. With one exception, mem_cgroup_update_lru_size(,lru,) is then used where __mod_zone_page_state(,NR_LRU_BASE+lru,) is used; and we shall be adding some more calls in a future commit. Make the code a little smaller and simpler by incorporating stat update in lru_size update. The exception was move_active_pages_to_lru(), which aggregated the pgmoved stat update separately from the individual lru_size updates; but I still think this a simplification worth making. However, the __mod_zone_page_state is not peculiar to mem_cgroups: so better use the name update_lru_size, calls mem_cgroup_update_lru_size when CONFIG_MEMCG. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0139aa7b |
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19-May-2016 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm: rename _count, field of the struct page, to _refcount Many developers already know that field for reference count of the struct page is _count and atomic type. They would try to handle it directly and this could break the purpose of page reference count tracepoint. To prevent direct _count modification, this patch rename it to _refcount and add warning message on the code. After that, developer who need to handle reference count will find that field should not be accessed directly. [akpm@linux-foundation.org: fix comments, per Vlastimil] [akpm@linux-foundation.org: Documentation/vm/transhuge.txt too] [sfr@canb.auug.org.au: sync ethernet driver changes] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Sunil Goutham <sgoutham@cavium.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Manish Chopra <manish.chopra@qlogic.com> Cc: Yuval Mintz <yuval.mintz@qlogic.com> Cc: Tariq Toukan <tariqt@mellanox.com> Cc: Saeed Mahameed <saeedm@mellanox.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fd901c95 |
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28-Apr-2016 |
Vlastimil Babka <vbabka@suse.cz> |
mm: wake kcompactd before kswapd's short sleep When kswapd goes to sleep it checks if the node is balanced and at first it sleeps only for HZ/10 time, then rechecks if the node is still balanced and nobody has woken it during the initial sleep. Only then it goes fully sleep until an allocation slowpath wakes it up again. For higher-order allocations, waking up kcompactd is done only before the full sleep. This turns out to be an issue in case another high-order allocation fails during the initial sleep. It will wake kswapd up, however kswapd considers the zone balanced from the order-0 perspective, and will just quickly try to sleep again. So if there's a longer stream of high-order allocations hitting the slowpath and waking up kswapd, it might never actually wake up kcompactd, which may be considered a regression from kswapd-based compaction. In the worst case, it might be that a single allocation that cannot direct reclaim/compact itself is waking kswapd in the retry loop and preventing kcompactd from being woken up and unblocking it. This patch makes sure kcompactd is woken up in such situations by simply moving the wakeup before the short initial sleep. More efficient solution would be to wake kcompactd immediately instead of kswapd if the node is already order-0 balanced, but in that case we should also move reset_isolation_suitable() call to kcompactd so it's not adding to the allocator's latency. Since it's late in the 4.6 cycle, let's go with the simpler change for now. Fixes: accf62422b3a ("mm, kswapd: replace kswapd compaction with waking up kcompactd") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7bf52fb8 |
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28-Apr-2016 |
Minchan Kim <minchan@kernel.org> |
mm: vmscan: reclaim highmem zone if buffer_heads is over limit We have been reclaimed highmem zone if buffer_heads is over limit but commit 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from shrink_zone()") changed the behavior so it doesn't reclaim highmem zone although buffer_heads is over the limit. This patch restores the logic. Fixes: 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from shrink_zone()") Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fe896d18 |
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17-Mar-2016 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm: introduce page reference manipulation functions The success of CMA allocation largely depends on the success of migration and key factor of it is page reference count. Until now, page reference is manipulated by direct calling atomic functions so we cannot follow up who and where manipulate it. Then, it is hard to find actual reason of CMA allocation failure. CMA allocation should be guaranteed to succeed so finding offending place is really important. In this patch, call sites where page reference is manipulated are converted to introduced wrapper function. This is preparation step to add tracepoint to each page reference manipulation function. With this facility, we can easily find reason of CMA allocation failure. There is no functional change in this patch. In addition, this patch also converts reference read sites. It will help a second step that renames page._count to something else and prevents later attempt to direct access to it (Suggested by Andrew). Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0fc9f58a |
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17-Mar-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: pass root_mem_cgroup instead of NULL to memcg aware shrinker It's just convenient to implement a memcg aware shrinker when you know that shrink_control->memcg != NULL unless memcg_kmem_enabled() returns false. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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accf6242 |
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17-Mar-2016 |
Vlastimil Babka <vbabka@suse.cz> |
mm, kswapd: replace kswapd compaction with waking up kcompactd Similarly to direct reclaim/compaction, kswapd attempts to combine reclaim and compaction to attempt making memory allocation of given order available. The details differ from direct reclaim e.g. in having high watermark as a goal. The code involved in kswapd's reclaim/compaction decisions has evolved to be quite complex. Testing reveals that it doesn't actually work in at least one scenario, and closer inspection suggests that it could be greatly simplified without compromising on the goal (make high-order page available) or efficiency (don't reclaim too much). The simplification relieas of doing all compaction in kcompactd, which is simply woken up when high watermarks are reached by kswapd's reclaim. The scenario where kswapd compaction doesn't work was found with mmtests test stress-highalloc configured to attempt order-9 allocations without direct reclaim, just waking up kswapd. There was no compaction attempt from kswapd during the whole test. Some added instrumentation shows what happens: - balance_pgdat() sets end_zone to Normal, as it's not balanced - reclaim is attempted on DMA zone, which sets nr_attempted to 99, but it cannot reclaim anything, so sc.nr_reclaimed is 0 - for zones DMA32 and Normal, kswapd_shrink_zone uses testorder=0, so it merely checks if high watermarks were reached for base pages. This is true, so no reclaim is attempted. For DMA, testorder=0 wasn't used, as compaction_suitable() returned COMPACT_SKIPPED - even though the pgdat_needs_compaction flag wasn't set to false, no compaction happens due to the condition sc.nr_reclaimed > nr_attempted being false (as 0 < 99) - priority-- due to nr_reclaimed being 0, repeat until priority reaches 0 pgdat_balanced() is false as only the small zone DMA appears balanced (curiously in that check, watermark appears OK and compaction_suitable() returns COMPACT_PARTIAL, because a lower classzone_idx is used there) Now, even if it was decided that reclaim shouldn't be attempted on the DMA zone, the scenario would be the same, as (sc.nr_reclaimed=0 > nr_attempted=0) is also false. The condition really should use >= as the comment suggests. Then there is a mismatch in the check for setting pgdat_needs_compaction to false using low watermark, while the rest uses high watermark, and who knows what other subtlety. Hopefully this demonstrates that this is unsustainable. Luckily we can simplify this a lot. The reclaim/compaction decisions make sense for direct reclaim scenario, but in kswapd, our primary goal is to reach high watermark in order-0 pages. Afterwards we can attempt compaction just once. Unlike direct reclaim, we don't reclaim extra pages (over the high watermark), the current code already disallows it for good reasons. After this patch, we simply wake up kcompactd to process the pgdat, after we have either succeeded or failed to reach the high watermarks in kswapd, which goes to sleep. We pass kswapd's order and classzone_idx, so kcompactd can apply the same criteria to determine which zones are worth compacting. Note that we use the classzone_idx from wakeup_kswapd(), not balanced_classzone_idx which can include higher zones that kswapd tried to balance too, but didn't consider them in pgdat_balanced(). Since kswapd now cannot create high-order pages itself, we need to adjust how it determines the zones to be balanced. The key element here is adding a "highorder" parameter to zone_balanced, which, when set to false, makes it consider only order-0 watermark instead of the desired higher order (this was done previously by kswapd_shrink_zone(), but not elsewhere). This false is passed for example in pgdat_balanced(). Importantly, wakeup_kswapd() uses true to make sure kswapd and thus kcompactd are woken up for a high-order allocation failure. The last thing is to decide what to do with pageblock_skip bitmap handling. Compaction maintains a pageblock_skip bitmap to record pageblocks where isolation recently failed. This bitmap can be reset by three ways: 1) direct compaction is restarting after going through the full deferred cycle 2) kswapd goes to sleep, and some other direct compaction has previously finished scanning the whole zone and set zone->compact_blockskip_flush. Note that a successful direct compaction clears this flag. 3) compaction was invoked manually via trigger in /proc The case 2) is somewhat fuzzy to begin with, but after introducing kcompactd we should update it. The check for direct compaction in 1), and to set the flush flag in 2) use current_is_kswapd(), which doesn't work for kcompactd. Thus, this patch adds bool direct_compaction to compact_control to use in 2). For the case 1) we remove the check completely - unlike the former kswapd compaction, kcompactd does use the deferred compaction functionality, so flushing tied to restarting from deferred compaction makes sense here. Note that when kswapd goes to sleep, kcompactd is woken up, so it will see the flushed pageblock_skip bits. This is different from when the former kswapd compaction observed the bits and I believe it makes more sense. Kcompactd can afford to be more thorough than a direct compaction trying to limit allocation latency, or kswapd whose primary goal is to reclaim. For testing, I used stress-highalloc configured to do order-9 allocations with GFP_NOWAIT|__GFP_HIGH|__GFP_COMP, so they relied just on kswapd/kcompactd reclaim/compaction (the interfering kernel builds in phases 1 and 2 work as usual): stress-highalloc 4.5-rc1+before 4.5-rc1+after -nodirect -nodirect Success 1 Min 1.00 ( 0.00%) 5.00 (-66.67%) Success 1 Mean 1.40 ( 0.00%) 6.20 (-55.00%) Success 1 Max 2.00 ( 0.00%) 7.00 (-16.67%) Success 2 Min 1.00 ( 0.00%) 5.00 (-66.67%) Success 2 Mean 1.80 ( 0.00%) 6.40 (-52.38%) Success 2 Max 3.00 ( 0.00%) 7.00 (-16.67%) Success 3 Min 34.00 ( 0.00%) 62.00 ( 1.59%) Success 3 Mean 41.80 ( 0.00%) 63.80 ( 1.24%) Success 3 Max 53.00 ( 0.00%) 65.00 ( 2.99%) User 3166.67 3181.09 System 1153.37 1158.25 Elapsed 1768.53 1799.37 4.5-rc1+before 4.5-rc1+after -nodirect -nodirect Direct pages scanned 32938 32797 Kswapd pages scanned 2183166 2202613 Kswapd pages reclaimed 2152359 2143524 Direct pages reclaimed 32735 32545 Percentage direct scans 1% 1% THP fault alloc 579 612 THP collapse alloc 304 316 THP splits 0 0 THP fault fallback 793 778 THP collapse fail 11 16 Compaction stalls 1013 1007 Compaction success 92 67 Compaction failures 920 939 Page migrate success 238457 721374 Page migrate failure 23021 23469 Compaction pages isolated 504695 1479924 Compaction migrate scanned 661390 8812554 Compaction free scanned 13476658 84327916 Compaction cost 262 838 After this patch we see improvements in allocation success rate (especially for phase 3) along with increased compaction activity. The compaction stalls (direct compaction) in the interfering kernel builds (probably THP's) also decreased somewhat thanks to kcompactd activity, yet THP alloc successes improved a bit. Note that elapsed and user time isn't so useful for this benchmark, because of the background interference being unpredictable. It's just to quickly spot some major unexpected differences. System time is somewhat more useful and that didn't increase. Also (after adjusting mmtests' ftrace monitor): Time kswapd awake 2547781 2269241 Time kcompactd awake 0 119253 Time direct compacting 939937 557649 Time kswapd compacting 0 0 Time kcompactd compacting 0 119099 The decrease of overal time spent compacting appears to not match the increased compaction stats. I suspect the tasks get rescheduled and since the ftrace monitor doesn't see that, the reported time is wall time, not CPU time. But arguably direct compactors care about overall latency anyway, whether busy compacting or waiting for CPU doesn't matter. And that latency seems to almost halved. It's also interesting how much time kswapd spent awake just going through all the priorities and failing to even try compacting, over and over. We can also configure stress-highalloc to perform both direct reclaim/compaction and wakeup kswapd/kcompactd, by using GFP_KERNEL|__GFP_HIGH|__GFP_COMP: stress-highalloc 4.5-rc1+before 4.5-rc1+after -direct -direct Success 1 Min 4.00 ( 0.00%) 9.00 (-50.00%) Success 1 Mean 8.00 ( 0.00%) 10.00 (-19.05%) Success 1 Max 12.00 ( 0.00%) 11.00 ( 15.38%) Success 2 Min 4.00 ( 0.00%) 9.00 (-50.00%) Success 2 Mean 8.20 ( 0.00%) 10.00 (-16.28%) Success 2 Max 13.00 ( 0.00%) 11.00 ( 8.33%) Success 3 Min 75.00 ( 0.00%) 74.00 ( 1.33%) Success 3 Mean 75.60 ( 0.00%) 75.20 ( 0.53%) Success 3 Max 77.00 ( 0.00%) 76.00 ( 0.00%) User 3344.73 3246.04 System 1194.24 1172.29 Elapsed 1838.04 1836.76 4.5-rc1+before 4.5-rc1+after -direct -direct Direct pages scanned 125146 120966 Kswapd pages scanned 2119757 2135012 Kswapd pages reclaimed 2073183 2108388 Direct pages reclaimed 124909 120577 Percentage direct scans 5% 5% THP fault alloc 599 652 THP collapse alloc 323 354 THP splits 0 0 THP fault fallback 806 793 THP collapse fail 17 16 Compaction stalls 2457 2025 Compaction success 906 518 Compaction failures 1551 1507 Page migrate success 2031423 2360608 Page migrate failure 32845 40852 Compaction pages isolated 4129761 4802025 Compaction migrate scanned 11996712 21750613 Compaction free scanned 214970969 344372001 Compaction cost 2271 2694 In this scenario, this patch doesn't change the overall success rate as direct compaction already tries all it can. There's however significant reduction in direct compaction stalls (that is, the number of allocations that went into direct compaction). The number of successes (i.e. direct compaction stalls that ended up with successful allocation) is reduced by the same number. This means the offload to kcompactd is working as expected, and direct compaction is reduced either due to detecting contention, or compaction deferred by kcompactd. In the previous version of this patchset there was some apparent reduction of success rate, but the changes in this version (such as using sync compaction only), new baseline kernel, and/or averaging results from 5 executions (my bet), made this go away. Ftrace-based stats seem to roughly agree: Time kswapd awake 2532984 2326824 Time kcompactd awake 0 257916 Time direct compacting 864839 735130 Time kswapd compacting 0 0 Time kcompactd compacting 0 257585 Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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81c5857b |
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17-Mar-2016 |
Vlastimil Babka <vbabka@suse.cz> |
mm, kswapd: remove bogus check of balance_classzone_idx During work on kcompactd integration I have spotted a confusing check of balance_classzone_idx, which I believe is bogus. The balanced_classzone_idx is filled by balance_pgdat() as the highest zone it attempted to balance. This was introduced by commit dc83edd941f4 ("mm: kswapd: use the classzone idx that kswapd was using for sleeping_prematurely()"). The intention is that (as expressed in today's function names), the value used for kswapd_shrink_zone() calls in balance_pgdat() is the same as for the decisions in kswapd_try_to_sleep(). An unwanted side-effect of that commit was breaking the checks in kswapd() whether there was another kswapd_wakeup with a tighter (=lower) classzone_idx. Commits 215ddd6664ce ("mm: vmscan: only read new_classzone_idx from pgdat when reclaiming successfully") and d2ebd0f6b895 ("kswapd: avoid unnecessary rebalance after an unsuccessful balancing") tried to fixed, but apparently introduced a bogus check that this patch removes. Consider zone indexes X < Y < Z, where: - Z is the value used for the first kswapd wakeup. - Y is returned as balanced_classzone_idx, which means zones with index higher than Y (including Z) were found to be unreclaimable. - X is the value used for the second kswapd wakeup The new wakeup with value X means that kswapd is now supposed to balance harder all zones with index <= X. But instead, due to Y < Z, it will go sleep and won't read the new value X. This is subtly wrong. The effect of this patch is that kswapd will react better in some situations, where e.g. the first wakeup is for ZONE_DMA32, the second is for ZONE_DMA, and due to unreclaimable ZONE_NORMAL. Before this patch, kswapd would go sleep instead of reclaiming ZONE_DMA harder. I expect these situations are very rare, and more value is in better maintainability due to the removal of confusing and bogus check. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fdf1cdb9 |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: remove unnecessary uses of lock_page_memcg() There are several users that nest lock_page_memcg() inside lock_page() to prevent page->mem_cgroup from changing. But the page lock prevents pages from moving between cgroups, so that is unnecessary overhead. Remove lock_page_memcg() in contexts with locked contexts and fix the debug code in the page stat functions to be okay with the page lock. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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62cccb8c |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: simplify lock_page_memcg() Now that migration doesn't clear page->mem_cgroup of live pages anymore, it's safe to make lock_page_memcg() and the memcg stat functions take pages, and spare the callers from memcg objects. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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23047a96 |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: workingset: per-cgroup cache thrash detection Cache thrash detection (see a528910e12ec "mm: thrash detection-based file cache sizing" for details) currently only works on the system level, not inside cgroups. Worse, as the refaults are compared to the global number of active cache, cgroups might wrongfully get all their refaults activated when their pages are hotter than those of others. Move the refault machinery from the zone to the lruvec, and then tag eviction entries with the memcg ID. This makes the thrash detection work correctly inside cgroups. [sergey.senozhatsky@gmail.com: do not return from workingset_activation() with locked rcu and page] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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81f8c3a4 |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: generalize locking for the page->mem_cgroup binding These patches tag the page cache radix tree eviction entries with the memcg an evicted page belonged to, thus making per-cgroup LRU reclaim work properly and be as adaptive to new cache workingsets as global reclaim already is. This should have been part of the original thrash detection patch series, but was deferred due to the complexity of those patches. This patch (of 5): So far the only sites that needed to exclude charge migration to stabilize page->mem_cgroup have been per-cgroup page statistics, hence the name mem_cgroup_begin_page_stat(). But per-cgroup thrash detection will add another site that needs to ensure page->mem_cgroup lifetime. Rename these locking functions to the more generic lock_page_memcg() and unlock_page_memcg(). Since charge migration is a cgroup1 feature only, we might be able to delete it at some point, and these now easy to identify locking sites along with it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0db2cb8d |
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15-Mar-2016 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: make zone_reclaimable_pages more precise zone_reclaimable_pages() is used in should_reclaim_retry() which uses it to calculate the target for the watermark check. This means that precise numbers are important for the correct decision. zone_reclaimable_pages uses zone_page_state which can contain stale data with per-cpu diffs not synced yet (the last vmstat_update might have run 1s in the past). Use zone_page_state_snapshot() in zone_reclaimable_pages() instead. None of the current callers is in a hot path where getting the precise value (which involves per-cpu iteration) would cause an unreasonable overhead. Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Suggested-by: David Rientjes <rientjes@google.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cecf257b |
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15-Mar-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: do not clear SHRINKER_NUMA_AWARE if nr_node_ids == 1 Currently, on shrinker registration we clear SHRINKER_NUMA_AWARE if there's the only NUMA node present. The comment states that this will allow us to save some small loop time later. It used to be true when this code was added (see commit 1d3d4437eae1b ("vmscan: per-node deferred work")), but since commit 6b4f7799c6a57 ("mm: vmscan: invoke slab shrinkers from shrink_zone()") it doesn't make any difference. Anyway, running on non-NUMA machine shouldn't make a shrinker NUMA unaware, so zap this hunk. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cf2a82ee |
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05-Feb-2016 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
mm: downgrade VM_BUG in isolate_lru_page() to warning Calling isolate_lru_page() is wrong and shouldn't happen, but it not nessesary fatal: the page just will not be isolated if it's not on LRU. Let's downgrade the VM_BUG_ON_PAGE() to WARN_RATELIMIT(). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f9fe48be |
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22-Jan-2016 |
Ross Zwisler <zwisler@kernel.org> |
dax: support dirty DAX entries in radix tree Add support for tracking dirty DAX entries in the struct address_space radix tree. This tree is already used for dirty page writeback, and it already supports the use of exceptional (non struct page*) entries. In order to properly track dirty DAX pages we will insert new exceptional entries into the radix tree that represent dirty DAX PTE or PMD pages. These exceptional entries will also contain the writeback addresses for the PTE or PMD faults that we can use at fsync/msync time. There are currently two types of exceptional entries (shmem and shadow) that can be placed into the radix tree, and this adds a third. We rely on the fact that only one type of exceptional entry can be found in a given radix tree based on its usage. This happens for free with DAX vs shmem but we explicitly prevent shadow entries from being added to radix trees for DAX mappings. The only shadow entries that would be generated for DAX radix trees would be to track zero page mappings that were created for holes. These pages would receive minimal benefit from having shadow entries, and the choice to have only one type of exceptional entry in a given radix tree makes the logic simpler both in clear_exceptional_entry() and in the rest of DAX. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Dave Chinner <david@fromorbit.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jan Kara <jack@suse.com> Cc: Jeff Layton <jlayton@poochiereds.net> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5ccc5aba |
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20-Jan-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: free swap cache aggressively if memcg swap is full Swap cache pages are freed aggressively if swap is nearly full (>50% currently), because otherwise we are likely to stop scanning anonymous when we near the swap limit even if there is plenty of freeable swap cache pages. We should follow the same trend in case of memory cgroup, which has its own swap limit. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d8b38438 |
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20-Jan-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: do not scan anon pages if memcg swap limit is hit We don't scan anonymous memory if we ran out of swap, neither should we do it in case memcg swap limit is hit, because swap out is impossible anyway. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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eb01aaab |
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20-Jan-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: memcontrol: replace mem_cgroup_lruvec_online with mem_cgroup_online mem_cgroup_lruvec_online() takes lruvec, but it only needs memcg. Since get_scan_count(), which is the only user of this function, now possesses pointer to memcg, let's pass memcg directly to mem_cgroup_online() instead of picking it out of lruvec and rename the function accordingly. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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33377678 |
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20-Jan-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: pass memcg to get_scan_count() memcg will come in handy in get_scan_count(). It can already be used for getting swappiness immediately in get_scan_count() instead of passing it around. The following patches will add more memcg-related values, which will be used there. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
567e9ab2 |
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20-Jan-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: give the kmem states more descriptive names On any given memcg, the kmem accounting feature has three separate states: not initialized, structures allocated, and actively accounting slab memory. These are represented through a combination of the kmem_acct_activated and kmem_acct_active flags, which is confusing. Convert to a kmem_state enum with the states NONE, ALLOCATED, and ONLINE. Then rename the functions to modify the state accordingly. This follows the nomenclature of css object states more closely. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
854e9ed0 |
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15-Jan-2016 |
Minchan Kim <minchan@kernel.org> |
mm: support madvise(MADV_FREE) Linux doesn't have an ability to free pages lazy while other OS already have been supported that named by madvise(MADV_FREE). The gain is clear that kernel can discard freed pages rather than swapping out or OOM if memory pressure happens. Without memory pressure, freed pages would be reused by userspace without another additional overhead(ex, page fault + allocation + zeroing). Jason Evans said: : Facebook has been using MAP_UNINITIALIZED : (https://lkml.org/lkml/2012/1/18/308) in some of its applications for : several years, but there are operational costs to maintaining this : out-of-tree in our kernel and in jemalloc, and we are anxious to retire it : in favor of MADV_FREE. When we first enabled MAP_UNINITIALIZED it : increased throughput for much of our workload by ~5%, and although the : benefit has decreased using newer hardware and kernels, there is still : enough benefit that we cannot reasonably retire it without a replacement. : : Aside from Facebook operations, there are numerous broadly used : applications that would benefit from MADV_FREE. The ones that immediately : come to mind are redis, varnish, and MariaDB. I don't have much insight : into Android internals and development process, but I would hope to see : MADV_FREE support eventually end up there as well to benefit applications : linked with the integrated jemalloc. : : jemalloc will use MADV_FREE once it becomes available in the Linux kernel. : In fact, jemalloc already uses MADV_FREE or equivalent everywhere it's : available: *BSD, OS X, Windows, and Solaris -- every platform except Linux : (and AIX, but I'm not sure it even compiles on AIX). The lack of : MADV_FREE on Linux forced me down a long series of increasingly : sophisticated heuristics for madvise() volume reduction, and even so this : remains a common performance issue for people using jemalloc on Linux. : Please integrate MADV_FREE; many people will benefit substantially. How it works: When madvise syscall is called, VM clears dirty bit of ptes of the range. If memory pressure happens, VM checks dirty bit of page table and if it found still "clean", it means it's a "lazyfree pages" so VM could discard the page instead of swapping out. Once there was store operation for the page before VM peek a page to reclaim, dirty bit is set so VM can swap out the page instead of discarding. One thing we should notice is that basically, MADV_FREE relies on dirty bit in page table entry to decide whether VM allows to discard the page or not. IOW, if page table entry includes marked dirty bit, VM shouldn't discard the page. However, as a example, if swap-in by read fault happens, page table entry doesn't have dirty bit so MADV_FREE could discard the page wrongly. For avoiding the problem, MADV_FREE did more checks with PageDirty and PageSwapCache. It worked out because swapped-in page lives on swap cache and since it is evicted from the swap cache, the page has PG_dirty flag. So both page flags check effectively prevent wrong discarding by MADV_FREE. However, a problem in above logic is that swapped-in page has PG_dirty still after they are removed from swap cache so VM cannot consider the page as freeable any more even if madvise_free is called in future. Look at below example for detail. ptr = malloc(); memset(ptr); .. .. .. heavy memory pressure so all of pages are swapped out .. .. var = *ptr; -> a page swapped-in and could be removed from swapcache. Then, page table doesn't mark dirty bit and page descriptor includes PG_dirty .. .. madvise_free(ptr); -> It doesn't clear PG_dirty of the page. .. .. .. .. heavy memory pressure again. .. In this time, VM cannot discard the page because the page .. has *PG_dirty* To solve the problem, this patch clears PG_dirty if only the page is owned exclusively by current process when madvise is called because PG_dirty represents ptes's dirtiness in several processes so we could clear it only if we own it exclusively. Firstly, heavy users would be general allocators(ex, jemalloc, tcmalloc and hope glibc supports it) and jemalloc/tcmalloc already have supported the feature for other OS(ex, FreeBSD) barrios@blaptop:~/benchmark/ebizzy$ lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 12 On-line CPU(s) list: 0-11 Thread(s) per core: 1 Core(s) per socket: 1 Socket(s): 12 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 2 Stepping: 3 CPU MHz: 3200.185 BogoMIPS: 6400.53 Virtualization: VT-x Hypervisor vendor: KVM Virtualization type: full L1d cache: 32K L1i cache: 32K L2 cache: 4096K NUMA node0 CPU(s): 0-11 ebizzy benchmark(./ebizzy -S 10 -n 512) Higher avg is better. vanilla-jemalloc MADV_free-jemalloc 1 thread records: 10 records: 10 avg: 2961.90 avg: 12069.70 std: 71.96(2.43%) std: 186.68(1.55%) max: 3070.00 max: 12385.00 min: 2796.00 min: 11746.00 2 thread records: 10 records: 10 avg: 5020.00 avg: 17827.00 std: 264.87(5.28%) std: 358.52(2.01%) max: 5244.00 max: 18760.00 min: 4251.00 min: 17382.00 4 thread records: 10 records: 10 avg: 8988.80 avg: 27930.80 std: 1175.33(13.08%) std: 3317.33(11.88%) max: 9508.00 max: 30879.00 min: 5477.00 min: 21024.00 8 thread records: 10 records: 10 avg: 13036.50 avg: 33739.40 std: 170.67(1.31%) std: 5146.22(15.25%) max: 13371.00 max: 40572.00 min: 12785.00 min: 24088.00 16 thread records: 10 records: 10 avg: 11092.40 avg: 31424.20 std: 710.60(6.41%) std: 3763.89(11.98%) max: 12446.00 max: 36635.00 min: 9949.00 min: 25669.00 32 thread records: 10 records: 10 avg: 11067.00 avg: 34495.80 std: 971.06(8.77%) std: 2721.36(7.89%) max: 12010.00 max: 38598.00 min: 9002.00 min: 30636.00 In summary, MADV_FREE is about much faster than MADV_DONTNEED. This patch (of 12): Add core MADV_FREE implementation. [akpm@linux-foundation.org: small cleanups] Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Mika Penttil <mika.penttila@nextfour.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Jason Evans <je@fb.com> Cc: Daniel Micay <danielmicay@gmail.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Shaohua Li <shli@kernel.org> Cc: <yalin.wang2010@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: "Shaohua Li" <shli@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen Gang <gang.chen.5i5j@gmail.com> Cc: Chris Zankel <chris@zankel.net> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: David S. Miller <davem@davemloft.net> Cc: Helge Deller <deller@gmx.de> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Roland Dreier <roland@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Shaohua Li <shli@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
48c935ad |
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15-Jan-2016 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
page-flags: define PG_locked behavior on compound pages lock_page() must operate on the whole compound page. It doesn't make much sense to lock part of compound page. Change code to use head page's PG_locked, if tail page is passed. This patch also gets rid of custom helper functions -- __set_page_locked() and __clear_page_locked(). They are replaced with helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG. Tail pages to these helper would trigger VM_BUG_ON(). SLUB uses PG_locked as a bit spin locked. IIUC, tail pages should never appear there. VM_BUG_ON() is added to make sure that this assumption is correct. [akpm@linux-foundation.org: fix fs/cifs/file.c] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bb5b8589 |
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14-Jan-2016 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
mm: make sure isolate_lru_page() is never called for tail page The VM_BUG_ON_PAGE() would catch such cases if any still exists. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8e8ae645 |
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14-Jan-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: hook up vmpressure to socket pressure Let the networking stack know when a memcg is under reclaim pressure so that it can clamp its transmit windows accordingly. Whenever the reclaim efficiency of a cgroup's LRU lists drops low enough for a MEDIUM or HIGH vmpressure event to occur, assert a pressure state in the socket and tcp memory code that tells it to curb consumption growth from sockets associated with said control group. Traditionally, vmpressure reports for the entire subtree of a memcg under pressure, which drops useful information on the individual groups reclaimed. However, it's too late to change the userinterface, so add a second reporting mode that reports on the level of reclaim instead of at the level of pressure, and use that report for sockets. vmpressure events are naturally edge triggered, so for hysteresis assert socket pressure for a second to allow for subsequent vmpressure events to occur before letting the socket code return to normal. This will likely need finetuning for a wider variety of workloads, but for now stick to the vmpressure presets and keep hysteresis simple. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David S. Miller <davem@davemloft.net> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c8ad6302 |
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14-Jan-2016 |
Geliang Tang <geliangtang@163.com> |
mm/readahead.c, mm/vmscan.c: use lru_to_page instead of list_to_page list_to_page() in readahead.c is the same as lru_to_page() in vmscan.c. So I move lru_to_page to internal.h and drop list_to_page(). Signed-off-by: Geliang Tang <geliangtang@163.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9f6c399d |
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14-Jan-2016 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: consider isolated pages in zone_reclaimable_pages zone_reclaimable_pages counts how many pages are reclaimable in the given zone. This currently includes all pages on file lrus and anon lrus if there is an available swap storage. We do not consider NR_ISOLATED_{ANON,FILE} counters though which is not correct because these counters reflect temporarily isolated pages which are still reclaimable because they either get back to their LRU or get freed either by the page reclaim or page migration. The number of these pages might be sufficiently high to confuse users of zone_reclaimable_pages (e.g. mbind can migrate large ranges of memory at once). Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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316bda0e |
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14-Jan-2016 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
vmscan: do not force-scan file lru if its absolute size is small We assume there is enough inactive page cache if the size of inactive file lru is greater than the size of active file lru, in which case we force-scan file lru ignoring anonymous pages. While this logic works fine when there are plenty of page cache pages, it fails if the size of file lru is small (several MB): in this case (lru_size >> prio) will be 0 for normal scan priorities, as a result, if inactive file lru happens to be larger than active file lru, anonymous pages of a cgroup will never get evicted unless the system experiences severe memory pressure, even if there are gigabytes of unused anonymous memory there, which is unfair in respect to other cgroups, whose workloads might be page cache oriented. This patch attempts to fix this by elaborating the "enough inactive page cache" check: it makes it not only check that inactive lru size > active lru size, but also that we will scan something from the cgroup at the current scan priority. If these conditions do not hold, we proceed to SCAN_FRACT as usual. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ba5e9579 |
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14-Jan-2016 |
yalin wang <yalin.wang2010@gmail.com> |
mm: change mm_vmscan_lru_shrink_inactive() proto types Move node_id zone_idx shrink flags into trace function, so thay we don't need caculate these args if the trace is disabled, and will make this function have less arguments. Signed-off-by: yalin wang <yalin.wang2010@gmail.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3aa23851 |
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14-Jan-2016 |
yalin wang <yalin.wang2010@gmail.com> |
mm/vmscan.c: change trace_mm_vmscan_writepage() proto type Move trace_reclaim_flags() into trace function, so that we don't need caculate these flags if the trace is disabled. Signed-off-by: yalin wang <yalin.wang2010@gmail.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d0164adc |
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06-Nov-2015 |
Mel Gorman <mgorman@techsingularity.net> |
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e2b19197 |
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06-Nov-2015 |
Mel Gorman <mgorman@techsingularity.net> |
mm, page_alloc: remove unnecessary parameter from zone_watermark_ok_safe Overall, the intent of this series is to remove the zonelist cache which was introduced to avoid high overhead in the page allocator. Once this is done, it is necessary to reduce the cost of watermark checks. The series starts with minor micro-optimisations. Next it notes that GFP flags that affect watermark checks are abused. __GFP_WAIT historically identified callers that could not sleep and could access reserves. This was later abused to identify callers that simply prefer to avoid sleeping and have other options. A patch distinguishes between atomic callers, high-priority callers and those that simply wish to avoid sleep. The zonelist cache has been around for a long time but it is of dubious merit with a lot of complexity and some issues that are explained. The most important issue is that a failed THP allocation can cause a zone to be treated as "full". This potentially causes unnecessary stalls, reclaim activity or remote fallbacks. The issues could be fixed but it's not worth it. The series places a small number of other micro-optimisations on top before examining GFP flags watermarks. High-order watermarks enforcement can cause high-order allocations to fail even though pages are free. The watermark checks both protect high-order atomic allocations and make kswapd aware of high-order pages but there is a much better way that can be handled using migrate types. This series uses page grouping by mobility to reserve pageblocks for high-order allocations with the size of the reservation depending on demand. kswapd awareness is maintained by examining the free lists. By patch 12 in this series, there are no high-order watermark checks while preserving the properties that motivated the introduction of the watermark checks. This patch (of 10): No user of zone_watermark_ok_safe() specifies alloc_flags. This patch removes the unnecessary parameter. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Christoph Lameter <cl@linux.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d031a157 |
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05-Nov-2015 |
Alexandru Moise <00moses.alexander00@gmail.com> |
mm/vmscan.c: fix types of some locals In zone_reclaimable_pages(), `nr' is returned by a function which is declared as returning "unsigned long", so declare it such. Negative values are meaningless here. In zone_pagecache_reclaimable() we should also declare `delta' and `nr_pagecache_reclaimable' as being unsigned longs because they're used to store the values returned by zone_page_state() and zone_unmapped_file_pages() which also happen to return unsigned integers. [akpm@linux-foundation.org: make zone_pagecache_reclaimable() return ulong rather than long] Signed-off-by: Alexandru Moise <00moses.alexander00@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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42e2e457 |
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05-Nov-2015 |
Yaowei Bai <bywxiaobai@163.com> |
mm/vmscan: make inactive_anon/file_is_low return bool Make inactive_anon/file_is_low return bool due to these particular functions only using either one or zero as their return value. No functional change. Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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29d06bbb |
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05-Nov-2015 |
Yaowei Bai <bywxiaobai@163.com> |
mm/vmscan: make inactive_anon_is_low_global return directly Delete unnecessary if to let inactive_anon_is_low_global return directly. No functional changes. Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d5028f9f |
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22-Sep-2015 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
vmscan: fix sane_reclaim helper for legacy memcg The sane_reclaim() helper is supposed to return false for memcg reclaim if the legacy hierarchy is used, because the latter lacks dirty throttling mechanism, and so it did before it was accidentally broken by commit 33398cf2f360c ("memcg: export struct mem_cgroup"). Fix it. Fixes: 33398cf2f360c ("memcg: export struct mem_cgroup") Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7fadc820 |
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08-Sep-2015 |
Hugh Dickins <hughd@google.com> |
mm, vmscan: unlock page while waiting on writeback This is merely a politeness: I've not found that shrink_page_list() leads to deadlock with the page it holds locked across wait_on_page_writeback(); but nevertheless, why hold others off by keeping the page locked there? And while we're at it: remove the mistaken "not " from the commentary on this Case 3 (and a distracting blank line from Case 2, if I may). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c54839a7 |
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08-Sep-2015 |
Jaewon Kim <jaewon31.kim@samsung.com> |
vmscan: fix increasing nr_isolated incurred by putback unevictable pages reclaim_clean_pages_from_list() assumes that shrink_page_list() returns number of pages removed from the candidate list. But shrink_page_list() puts back mlocked pages without passing it to caller and without counting as nr_reclaimed. This increases nr_isolated. To fix this, this patch changes shrink_page_list() to pass unevictable pages back to caller. Caller will take care those pages. Minchan said: It fixes two issues. 1. With unevictable page, cma_alloc will be successful. Exactly speaking, cma_alloc of current kernel will fail due to unevictable pages. 2. fix leaking of NR_ISOLATED counter of vmstat With it, too_many_isolated works. Otherwise, it could make hang until the process get SIGKILL. Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0b802f10 |
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08-Sep-2015 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: never isolate more pages than necessary If transparent huge pages are enabled, we can isolate many more pages than we actually need to scan, because we count both single and huge pages equally in isolate_lru_pages(). Since commit 5bc7b8aca942d ("mm: thp: add split tail pages to shrink page list in page reclaim"), we scan all the tail pages immediately after a huge page split (see shrink_page_list()). As a result, we can reclaim up to SWAP_CLUSTER_MAX * HPAGE_PMD_NR (512 MB) in one run! This is easy to catch on memcg reclaim with zswap enabled. The latter makes swapout instant so that if we happen to scan an unreferenced huge page we will evict both its head and tail pages immediately, which is likely to result in excessive reclaim. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
33398cf2 |
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08-Sep-2015 |
Michal Hocko <mhocko@suse.cz> |
memcg: export struct mem_cgroup mem_cgroup structure is defined in mm/memcontrol.c currently which means that the code outside of this file has to use external API even for trivial access stuff. This patch exports mm_struct with its dependencies and makes some of the exported functions inlines. This even helps to reduce the code size a bit (make defconfig + CONFIG_MEMCG=y) text data bss dec hex filename 12355346 1823792 1089536 15268674 e8fb42 vmlinux.before 12354970 1823792 1089536 15268298 e8f9ca vmlinux.after This is not much (370B) but better than nothing. We also save a function call in some hot paths like callers of mem_cgroup_count_vm_event which is used for accounting. The patch doesn't introduce any functional changes. [vdavykov@parallels.com: inline memcg_kmem_is_active] [vdavykov@parallels.com: do not expose type outside of CONFIG_MEMCG] [akpm@linux-foundation.org: memcontrol.h needs eventfd.h for eventfd_ctx] [akpm@linux-foundation.org: export mem_cgroup_from_task() to modules] Signed-off-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d950c947 |
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04-Sep-2015 |
Mel Gorman <mgorman@suse.de> |
mm: defer flush of writable TLB entries If a PTE is unmapped and it's dirty then it was writable recently. Due to deferred TLB flushing, it's best to assume a writable TLB cache entry exists. With that assumption, the TLB must be flushed before any IO can start or the page is freed to avoid lost writes or data corruption. This patch defers flushing of potentially writable TLBs as long as possible. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
72b252ae |
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04-Sep-2015 |
Mel Gorman <mgorman@suse.de> |
mm: send one IPI per CPU to TLB flush all entries after unmapping pages An IPI is sent to flush remote TLBs when a page is unmapped that was potentially accesssed by other CPUs. There are many circumstances where this happens but the obvious one is kswapd reclaiming pages belonging to a running process as kswapd and the task are likely running on separate CPUs. On small machines, this is not a significant problem but as machine gets larger with more cores and more memory, the cost of these IPIs can be high. This patch uses a simple structure that tracks CPUs that potentially have TLB entries for pages being unmapped. When the unmapping is complete, the full TLB is flushed on the assumption that a refill cost is lower than flushing individual entries. Architectures wishing to do this must give the following guarantee. If a clean page is unmapped and not immediately flushed, the architecture must guarantee that a write to that linear address from a CPU with a cached TLB entry will trap a page fault. This is essentially what the kernel already depends on but the window is much larger with this patch applied and is worth highlighting. The architecture should consider whether the cost of the full TLB flush is higher than sending an IPI to flush each individual entry. An additional architecture helper called flush_tlb_local is required. It's a trivial wrapper with some accounting in the x86 case. The impact of this patch depends on the workload as measuring any benefit requires both mapped pages co-located on the LRU and memory pressure. The case with the biggest impact is multiple processes reading mapped pages taken from the vm-scalability test suite. The test case uses NR_CPU readers of mapped files that consume 10*RAM. Linear mapped reader on a 4-node machine with 64G RAM and 48 CPUs 4.2.0-rc1 4.2.0-rc1 vanilla flushfull-v7 Ops lru-file-mmap-read-elapsed 159.62 ( 0.00%) 120.68 ( 24.40%) Ops lru-file-mmap-read-time_range 30.59 ( 0.00%) 2.80 ( 90.85%) Ops lru-file-mmap-read-time_stddv 6.70 ( 0.00%) 0.64 ( 90.38%) 4.2.0-rc1 4.2.0-rc1 vanilla flushfull-v7 User 581.00 611.43 System 5804.93 4111.76 Elapsed 161.03 122.12 This is showing that the readers completed 24.40% faster with 29% less system CPU time. From vmstats, it is known that the vanilla kernel was interrupted roughly 900K times per second during the steady phase of the test and the patched kernel was interrupts 180K times per second. The impact is lower on a single socket machine. 4.2.0-rc1 4.2.0-rc1 vanilla flushfull-v7 Ops lru-file-mmap-read-elapsed 25.33 ( 0.00%) 20.38 ( 19.54%) Ops lru-file-mmap-read-time_range 0.91 ( 0.00%) 1.44 (-58.24%) Ops lru-file-mmap-read-time_stddv 0.28 ( 0.00%) 0.47 (-65.34%) 4.2.0-rc1 4.2.0-rc1 vanilla flushfull-v7 User 58.09 57.64 System 111.82 76.56 Elapsed 27.29 22.55 It's still a noticeable improvement with vmstat showing interrupts went from roughly 500K per second to 45K per second. The patch will have no impact on workloads with no memory pressure or have relatively few mapped pages. It will have an unpredictable impact on the workload running on the CPU being flushed as it'll depend on how many TLB entries need to be refilled and how long that takes. Worst case, the TLB will be completely cleared of active entries when the target PFNs were not resident at all. [sasha.levin@oracle.com: trace tlb flush after disabling preemption in try_to_unmap_flush] Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ecf5fc6e |
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04-Aug-2015 |
Michal Hocko <mhocko@suse.cz> |
mm, vmscan: Do not wait for page writeback for GFP_NOFS allocations Nikolay has reported a hang when a memcg reclaim got stuck with the following backtrace: PID: 18308 TASK: ffff883d7c9b0a30 CPU: 1 COMMAND: "rsync" #0 __schedule at ffffffff815ab152 #1 schedule at ffffffff815ab76e #2 schedule_timeout at ffffffff815ae5e5 #3 io_schedule_timeout at ffffffff815aad6a #4 bit_wait_io at ffffffff815abfc6 #5 __wait_on_bit at ffffffff815abda5 #6 wait_on_page_bit at ffffffff8111fd4f #7 shrink_page_list at ffffffff81135445 #8 shrink_inactive_list at ffffffff81135845 #9 shrink_lruvec at ffffffff81135ead #10 shrink_zone at ffffffff811360c3 #11 shrink_zones at ffffffff81136eff #12 do_try_to_free_pages at ffffffff8113712f #13 try_to_free_mem_cgroup_pages at ffffffff811372be #14 try_charge at ffffffff81189423 #15 mem_cgroup_try_charge at ffffffff8118c6f5 #16 __add_to_page_cache_locked at ffffffff8112137d #17 add_to_page_cache_lru at ffffffff81121618 #18 pagecache_get_page at ffffffff8112170b #19 grow_dev_page at ffffffff811c8297 #20 __getblk_slow at ffffffff811c91d6 #21 __getblk_gfp at ffffffff811c92c1 #22 ext4_ext_grow_indepth at ffffffff8124565c #23 ext4_ext_create_new_leaf at ffffffff81246ca8 #24 ext4_ext_insert_extent at ffffffff81246f09 #25 ext4_ext_map_blocks at ffffffff8124a848 #26 ext4_map_blocks at ffffffff8121a5b7 #27 mpage_map_one_extent at ffffffff8121b1fa #28 mpage_map_and_submit_extent at ffffffff8121f07b #29 ext4_writepages at ffffffff8121f6d5 #30 do_writepages at ffffffff8112c490 #31 __filemap_fdatawrite_range at ffffffff81120199 #32 filemap_flush at ffffffff8112041c #33 ext4_alloc_da_blocks at ffffffff81219da1 #34 ext4_rename at ffffffff81229b91 #35 ext4_rename2 at ffffffff81229e32 #36 vfs_rename at ffffffff811a08a5 #37 SYSC_renameat2 at ffffffff811a3ffc #38 sys_renameat2 at ffffffff811a408e #39 sys_rename at ffffffff8119e51e #40 system_call_fastpath at ffffffff815afa89 Dave Chinner has properly pointed out that this is a deadlock in the reclaim code because ext4 doesn't submit pages which are marked by PG_writeback right away. The heuristic was introduced by commit e62e384e9da8 ("memcg: prevent OOM with too many dirty pages") and it was applied only when may_enter_fs was specified. The code has been changed by c3b94f44fcb0 ("memcg: further prevent OOM with too many dirty pages") which has removed the __GFP_FS restriction with a reasoning that we do not get into the fs code. But this is not sufficient apparently because the fs doesn't necessarily submit pages marked PG_writeback for IO right away. ext4_bio_write_page calls io_submit_add_bh but that doesn't necessarily submit the bio. Instead it tries to map more pages into the bio and mpage_map_one_extent might trigger memcg charge which might end up waiting on a page which is marked PG_writeback but hasn't been submitted yet so we would end up waiting for something that never finishes. Fix this issue by replacing __GFP_IO by may_enter_fs check (for case 2) before we go to wait on the writeback. The page fault path, which is the only path that triggers memcg oom killer since 3.12, shouldn't require GFP_NOFS and so we shouldn't reintroduce the premature OOM killer issue which was originally addressed by the heuristic. As per David Chinner the xfs is doing similar thing since 2.6.15 already so ext4 is not the only affected filesystem. Moreover he notes: : For example: IO completion might require unwritten extent conversion : which executes filesystem transactions and GFP_NOFS allocations. The : writeback flag on the pages can not be cleared until unwritten : extent conversion completes. Hence memory reclaim cannot wait on : page writeback to complete in GFP_NOFS context because it is not : safe to do so, memcg reclaim or otherwise. Cc: stable@vger.kernel.org # 3.9+ [tytso@mit.edu: corrected the control flow] Fixes: c3b94f44fcb0 ("memcg: further prevent OOM with too many dirty pages") Reported-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0e1cc95b |
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30-Jun-2015 |
Mel Gorman <mgorman@suse.de> |
mm: meminit: finish initialisation of struct pages before basic setup Waiman Long reported that 24TB machines hit OOM during basic setup when struct page initialisation was deferred. One approach is to initialise memory on demand but it interferes with page allocator paths. This patch creates dedicated threads to initialise memory before basic setup. It then blocks on a rw_semaphore until completion as a wait_queue and counter is overkill. This may be slower to boot but it's simplier overall and also gets rid of a section mangling which existed so kswapd could do the initialisation. [akpm@linux-foundation.org: include rwsem.h, use DECLARE_RWSEM, fix comment, remove unneeded cast] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Waiman Long <waiman.long@hp.com Cc: Nathan Zimmer <nzimmer@sgi.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Scott Norton <scott.norton@hp.com> Tested-by: Daniel J Blueman <daniel@numascale.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7e18adb4 |
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30-Jun-2015 |
Mel Gorman <mgorman@suse.de> |
mm: meminit: initialise remaining struct pages in parallel with kswapd Only a subset of struct pages are initialised at the moment. When this patch is applied kswapd initialise the remaining struct pages in parallel. This should boot faster by spreading the work to multiple CPUs and initialising data that is local to the CPU. The user-visible effect on large machines is that free memory will appear to rapidly increase early in the lifetime of the system until kswapd reports that all memory is initialised in the kernel log. Once initialised there should be no other user-visibile effects. Signed-off-by: Mel Gorman <mgorman@suse.de> Tested-by: Nate Zimmer <nzimmer@sgi.com> Tested-by: Waiman Long <waiman.long@hp.com> Tested-by: Daniel J Blueman <daniel@numascale.com> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Robin Holt <robinmholt@gmail.com> Cc: Nate Zimmer <nzimmer@sgi.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Waiman Long <waiman.long@hp.com> Cc: Scott Norton <scott.norton@hp.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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95bbc0c7 |
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24-Jun-2015 |
Zhihui Zhang <zzhsuny@gmail.com> |
mm: rename RECLAIM_SWAP to RECLAIM_UNMAP The name SWAP implies that we are dealing with anonymous pages only. In fact, the original patch that introduced the min_unmapped_ratio logic was to fix an issue related to file pages. Rename it to RECLAIM_UNMAP to match what does. Historically, commit a6dc60f8975a ("vmscan: rename sc.may_swap to may_unmap") renamed .may_swap to .may_unmap, leaving RECLAIM_SWAP behind. commit 2e2e42598908 ("vmscan,memcg: reintroduce sc->may_swap") reintroduced .may_swap for memory controller. Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f012a84a |
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24-Jun-2015 |
Nishanth Aravamudan <nacc@linux.vnet.ibm.com> |
mm: vmscan: do not throttle based on pfmemalloc reserves if node has no reclaimable pages Based upon 675becce15 ("mm: vmscan: do not throttle based on pfmemalloc reserves if node has no ZONE_NORMAL") from Mel. We have a system with the following topology: # numactl -H available: 3 nodes (0,2-3) node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 node 0 size: 28273 MB node 0 free: 27323 MB node 2 cpus: node 2 size: 16384 MB node 2 free: 0 MB node 3 cpus: 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 node 3 size: 30533 MB node 3 free: 13273 MB node distances: node 0 2 3 0: 10 20 20 2: 20 10 20 3: 20 20 10 Node 2 has no free memory, because: # cat /sys/devices/system/node/node2/hugepages/hugepages-16777216kB/nr_hugepages 1 This leads to the following zoneinfo: Node 2, zone DMA pages free 0 min 1840 low 2300 high 2760 scanned 0 spanned 262144 present 262144 managed 262144 ... all_unreclaimable: 1 If one then attempts to allocate some normal 16M hugepages via echo 37 > /proc/sys/vm/nr_hugepages The echo never returns and kswapd2 consumes CPU cycles. This is because throttle_direct_reclaim ends up calling wait_event(pfmemalloc_wait, pfmemalloc_watermark_ok...). pfmemalloc_watermark_ok() in turn checks all zones on the node if there are any reserves, and if so, then indicates the watermarks are ok, by seeing if there are sufficient free pages. 675becce15 added a condition already for memoryless nodes. In this case, though, the node has memory, it is just all consumed (and not reclaimable). Effectively, though, the result is the same on this call to pfmemalloc_watermark_ok() and thus seems like a reasonable additional condition. With this change, the afore-mentioned 16M hugepage allocation attempt succeeds and correctly round-robins between Nodes 1 and 3. Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Anton Blanchard <anton@samba.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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97c9341f |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use Because writeback wasn't cgroup aware before, the usual dirty throttling mechanism in balance_dirty_pages() didn't work for processes under memcg limit. The writeback path didn't know how much memory is available or how fast the dirty pages are being written out for a given memcg and balance_dirty_pages() didn't have any measure of IO back pressure for the memcg. To work around the issue, memcg implemented an ad-hoc dirty throttling mechanism in the direct reclaim path by stalling on pages under writeback which are encountered during direct reclaim scan. This is rather ugly and crude - none of the configurability, fairness, or bandwidth-proportional distribution of the normal path. The previous patches implemented proper memcg aware dirty throttling when cgroup writeback is in use making the ad-hoc mechanism unnecessary. This patch disables direct reclaim stalling for such case. Note: I disabled the parts which seemed obvious and it behaves fine while testing but my understanding of this code path is rudimentary and it's quite possible that I got something wrong. Please let me know if I got some wrong or more global_reclaim() sites should be updated. v2: The original patch removed the direct stalling mechanism which breaks legacy hierarchies. Conditionalize instead of removing. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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703c2708 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: implement and use inode_congested() In several places, bdi_congested() and its wrappers are used to determine whether more IOs should be issued. With cgroup writeback support, this question can't be answered solely based on the bdi (backing_dev_info). It's dependent on whether the filesystem and bdi support cgroup writeback and the blkcg the inode is associated with. This patch implements inode_congested() and its wrappers which take @inode and determines the congestion state considering cgroup writeback. The new functions replace bdi_*congested() calls in places where the query is about specific inode and task. There are several filesystem users which also fit this criteria but they should be updated when each filesystem implements cgroup writeback support. v2: Now that a given inode is associated with only one wb, congestion state can be determined independent from the asking task. Drop @task. Spotted by Vivek. Also, converted to take @inode instead of @mapping and renamed to inode_congested(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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c4843a75 |
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22-May-2015 |
Greg Thelen <gthelen@google.com> |
memcg: add per cgroup dirty page accounting When modifying PG_Dirty on cached file pages, update the new MEM_CGROUP_STAT_DIRTY counter. This is done in the same places where global NR_FILE_DIRTY is managed. The new memcg stat is visible in the per memcg memory.stat cgroupfs file. The most recent past attempt at this was http://thread.gmane.org/gmane.linux.kernel.cgroups/8632 The new accounting supports future efforts to add per cgroup dirty page throttling and writeback. It also helps an administrator break down a container's memory usage and provides evidence to understand memcg oom kills (the new dirty count is included in memcg oom kill messages). The ability to move page accounting between memcg (memory.move_charge_at_immigrate) makes this accounting more complicated than the global counter. The existing mem_cgroup_{begin,end}_page_stat() lock is used to serialize move accounting with stat updates. Typical update operation: memcg = mem_cgroup_begin_page_stat(page) if (TestSetPageDirty()) { [...] mem_cgroup_update_page_stat(memcg) } mem_cgroup_end_page_stat(memcg) Summary of mem_cgroup_end_page_stat() overhead: - Without CONFIG_MEMCG it's a no-op - With CONFIG_MEMCG and no inter memcg task movement, it's just rcu_read_lock() - With CONFIG_MEMCG and inter memcg task movement, it's rcu_read_lock() + spin_lock_irqsave() A memcg parameter is added to several routines because their callers now grab mem_cgroup_begin_page_stat() which returns the memcg later needed by for mem_cgroup_update_page_stat(). Because mem_cgroup_begin_page_stat() may disable interrupts, some adjustments are needed: - move __mark_inode_dirty() from __set_page_dirty() to its caller. __mark_inode_dirty() locking does not want interrupts disabled. - use spin_lock_irqsave(tree_lock) rather than spin_lock_irq() in __delete_from_page_cache(), replace_page_cache_page(), invalidate_complete_page2(), and __remove_mapping(). text data bss dec hex filename 8925147 1774832 1785856 12485835 be84cb vmlinux-!CONFIG_MEMCG-before 8925339 1774832 1785856 12486027 be858b vmlinux-!CONFIG_MEMCG-after +192 text bytes 8965977 1784992 1785856 12536825 bf4bf9 vmlinux-CONFIG_MEMCG-before 8966750 1784992 1785856 12537598 bf4efe vmlinux-CONFIG_MEMCG-after +773 text bytes Performance tests run on v4.0-rc1-36-g4f671fe2f952. Lower is better for all metrics, they're all wall clock or cycle counts. The read and write fault benchmarks just measure fault time, they do not include I/O time. * CONFIG_MEMCG not set: baseline patched kbuild 1m25.030000(+-0.088% 3 samples) 1m25.426667(+-0.120% 3 samples) dd write 100 MiB 0.859211561 +-15.10% 0.874162885 +-15.03% dd write 200 MiB 1.670653105 +-17.87% 1.669384764 +-11.99% dd write 1000 MiB 8.434691190 +-14.15% 8.474733215 +-14.77% read fault cycles 254.0(+-0.000% 10 samples) 253.0(+-0.000% 10 samples) write fault cycles 2021.2(+-3.070% 10 samples) 1984.5(+-1.036% 10 samples) * CONFIG_MEMCG=y root_memcg: baseline patched kbuild 1m25.716667(+-0.105% 3 samples) 1m25.686667(+-0.153% 3 samples) dd write 100 MiB 0.855650830 +-14.90% 0.887557919 +-14.90% dd write 200 MiB 1.688322953 +-12.72% 1.667682724 +-13.33% dd write 1000 MiB 8.418601605 +-14.30% 8.673532299 +-15.00% read fault cycles 266.0(+-0.000% 10 samples) 266.0(+-0.000% 10 samples) write fault cycles 2051.7(+-1.349% 10 samples) 2049.6(+-1.686% 10 samples) * CONFIG_MEMCG=y non-root_memcg: baseline patched kbuild 1m26.120000(+-0.273% 3 samples) 1m25.763333(+-0.127% 3 samples) dd write 100 MiB 0.861723964 +-15.25% 0.818129350 +-14.82% dd write 200 MiB 1.669887569 +-13.30% 1.698645885 +-13.27% dd write 1000 MiB 8.383191730 +-14.65% 8.351742280 +-14.52% read fault cycles 265.7(+-0.172% 10 samples) 267.0(+-0.000% 10 samples) write fault cycles 2070.6(+-1.512% 10 samples) 2084.4(+-2.148% 10 samples) As expected anon page faults are not affected by this patch. tj: Updated to apply on top of the recent cancel_dirty_page() changes. Signed-off-by: Sha Zhengju <handai.szj@gmail.com> Signed-off-by: Greg Thelen <gthelen@google.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
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cb731d6c |
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12-Feb-2015 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
vmscan: per memory cgroup slab shrinkers This patch adds SHRINKER_MEMCG_AWARE flag. If a shrinker has this flag set, it will be called per memory cgroup. The memory cgroup to scan objects from is passed in shrink_control->memcg. If the memory cgroup is NULL, a memcg aware shrinker is supposed to scan objects from the global list. Unaware shrinkers are only called on global pressure with memcg=NULL. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
241994ed |
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11-Feb-2015 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: default hierarchy interface for memory Introduce the basic control files to account, partition, and limit memory using cgroups in default hierarchy mode. This interface versioning allows us to address fundamental design issues in the existing memory cgroup interface, further explained below. The old interface will be maintained indefinitely, but a clearer model and improved workload performance should encourage existing users to switch over to the new one eventually. The control files are thus: - memory.current shows the current consumption of the cgroup and its descendants, in bytes. - memory.low configures the lower end of the cgroup's expected memory consumption range. The kernel considers memory below that boundary to be a reserve - the minimum that the workload needs in order to make forward progress - and generally avoids reclaiming it, unless there is an imminent risk of entering an OOM situation. - memory.high configures the upper end of the cgroup's expected memory consumption range. A cgroup whose consumption grows beyond this threshold is forced into direct reclaim, to work off the excess and to throttle new allocations heavily, but is generally allowed to continue and the OOM killer is not invoked. - memory.max configures the hard maximum amount of memory that the cgroup is allowed to consume before the OOM killer is invoked. - memory.events shows event counters that indicate how often the cgroup was reclaimed while below memory.low, how often it was forced to reclaim excess beyond memory.high, how often it hit memory.max, and how often it entered OOM due to memory.max. This allows users to identify configuration problems when observing a degradation in workload performance. An overcommitted system will have an increased rate of low boundary breaches, whereas increased rates of high limit breaches, maximum hits, or even OOM situations will indicate internally overcommitted cgroups. For existing users of memory cgroups, the following deviations from the current interface are worth pointing out and explaining: - The original lower boundary, the soft limit, is defined as a limit that is per default unset. As a result, the set of cgroups that global reclaim prefers is opt-in, rather than opt-out. The costs for optimizing these mostly negative lookups are so high that the implementation, despite its enormous size, does not even provide the basic desirable behavior. First off, the soft limit has no hierarchical meaning. All configured groups are organized in a global rbtree and treated like equal peers, regardless where they are located in the hierarchy. This makes subtree delegation impossible. Second, the soft limit reclaim pass is so aggressive that it not just introduces high allocation latencies into the system, but also impacts system performance due to overreclaim, to the point where the feature becomes self-defeating. The memory.low boundary on the other hand is a top-down allocated reserve. A cgroup enjoys reclaim protection when it and all its ancestors are below their low boundaries, which makes delegation of subtrees possible. Secondly, new cgroups have no reserve per default and in the common case most cgroups are eligible for the preferred reclaim pass. This allows the new low boundary to be efficiently implemented with just a minor addition to the generic reclaim code, without the need for out-of-band data structures and reclaim passes. Because the generic reclaim code considers all cgroups except for the ones running low in the preferred first reclaim pass, overreclaim of individual groups is eliminated as well, resulting in much better overall workload performance. - The original high boundary, the hard limit, is defined as a strict limit that can not budge, even if the OOM killer has to be called. But this generally goes against the goal of making the most out of the available memory. The memory consumption of workloads varies during runtime, and that requires users to overcommit. But doing that with a strict upper limit requires either a fairly accurate prediction of the working set size or adding slack to the limit. Since working set size estimation is hard and error prone, and getting it wrong results in OOM kills, most users tend to err on the side of a looser limit and end up wasting precious resources. The memory.high boundary on the other hand can be set much more conservatively. When hit, it throttles allocations by forcing them into direct reclaim to work off the excess, but it never invokes the OOM killer. As a result, a high boundary that is chosen too aggressively will not terminate the processes, but instead it will lead to gradual performance degradation. The user can monitor this and make corrections until the minimal memory footprint that still gives acceptable performance is found. In extreme cases, with many concurrent allocations and a complete breakdown of reclaim progress within the group, the high boundary can be exceeded. But even then it's mostly better to satisfy the allocation from the slack available in other groups or the rest of the system than killing the group. Otherwise, memory.max is there to limit this type of spillover and ultimately contain buggy or even malicious applications. - The original control file names are unwieldy and inconsistent in many different ways. For example, the upper boundary hit count is exported in the memory.failcnt file, but an OOM event count has to be manually counted by listening to memory.oom_control events, and lower boundary / soft limit events have to be counted by first setting a threshold for that value and then counting those events. Also, usage and limit files encode their units in the filename. That makes the filenames very long, even though this is not information that a user needs to be reminded of every time they type out those names. To address these naming issues, as well as to signal clearly that the new interface carries a new configuration model, the naming conventions in it necessarily differ from the old interface. - The original limit files indicate the state of an unset limit with a very high number, and a configured limit can be unset by echoing -1 into those files. But that very high number is implementation and architecture dependent and not very descriptive. And while -1 can be understood as an underflow into the highest possible value, -2 or -10M etc. do not work, so it's not inconsistent. memory.low, memory.high, and memory.max will use the string "infinity" to indicate and set the highest possible value. [akpm@linux-foundation.org: use seq_puts() for basic strings] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
90cbc250 |
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11-Feb-2015 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
vmscan: force scan offline memory cgroups Since commit b2052564e66d ("mm: memcontrol: continue cache reclaim from offlined groups") pages charged to a memory cgroup are not reparented when the cgroup is removed. Instead, they are supposed to be reclaimed in a regular way, along with pages accounted to online memory cgroups. However, an lruvec of an offline memory cgroup will sooner or later get so small that it will be scanned only at low scan priorities (see get_scan_count()). Therefore, if there are enough reclaimable pages in big lruvecs, pages accounted to offline memory cgroups will never be scanned at all, wasting memory. Fix this by unconditionally forcing scanning dead lruvecs from kswapd. [akpm@linux-foundation.org: fix build] Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
cfc51155 |
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11-Feb-2015 |
Vlastimil Babka <vbabka@suse.cz> |
mm, vmscan: wake up all pfmemalloc-throttled processes at once Kswapd in balance_pgdate() currently uses wake_up() on processes waiting in throttle_direct_reclaim(), which only wakes up a single process. This might leave processes waiting for longer than necessary, until the check is reached in the next loop iteration. Processes might also be left waiting if zone was fully balanced in single iteration. Note that the comment in balance_pgdat() also says "Wake them", so waking up a single process does not seem intentional. Thus, replace wake_up() with wake_up_all(). Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
17636faa |
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26-Jan-2015 |
Michael S. Tsirkin <mst@redhat.com> |
mm/vmscan: fix highidx argument type for_each_zone_zonelist_nodemask wants an enum zone_type argument, but is passed gfp_t: mm/vmscan.c:2658:9: expected int enum zone_type [signed] highest_zoneidx mm/vmscan.c:2658:9: got restricted gfp_t [usertype] gfp_mask mm/vmscan.c:2658:9: warning: incorrect type in argument 2 (different base types) mm/vmscan.c:2658:9: expected int enum zone_type [signed] highest_zoneidx mm/vmscan.c:2658:9: got restricted gfp_t [usertype] gfp_mask convert argument to the correct type. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Suleiman Souhlal <suleiman@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
de1414a6 |
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14-Jan-2015 |
Christoph Hellwig <hch@lst.de> |
fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info Now that we got rid of the bdi abuse on character devices we can always use sb->s_bdi to get at the backing_dev_info for a file, except for the block device special case. Export inode_to_bdi and replace uses of mapping->backing_dev_info with it to prepare for the removal of mapping->backing_dev_info. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
9e5e3661 |
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08-Jan-2015 |
Vlastimil Babka <vbabka@suse.cz> |
mm, vmscan: prevent kswapd livelock due to pfmemalloc-throttled process being killed Charles Shirron and Paul Cassella from Cray Inc have reported kswapd stuck in a busy loop with nothing left to balance, but kswapd_try_to_sleep() failing to sleep. Their analysis found the cause to be a combination of several factors: 1. A process is waiting in throttle_direct_reclaim() on pgdat->pfmemalloc_wait 2. The process has been killed (by OOM in this case), but has not yet been scheduled to remove itself from the waitqueue and die. 3. kswapd checks for throttled processes in prepare_kswapd_sleep(): if (waitqueue_active(&pgdat->pfmemalloc_wait)) { wake_up(&pgdat->pfmemalloc_wait); return false; // kswapd will not go to sleep } However, for a process that was already killed, wake_up() does not remove the process from the waitqueue, since try_to_wake_up() checks its state first and returns false when the process is no longer waiting. 4. kswapd is running on the same CPU as the only CPU that the process is allowed to run on (through cpus_allowed, or possibly single-cpu system). 5. CONFIG_PREEMPT_NONE=y kernel is used. If there's nothing to balance, kswapd encounters no voluntary preemption points and repeatedly fails prepare_kswapd_sleep(), blocking the process from running and removing itself from the waitqueue, which would let kswapd sleep. So, the source of the problem is that we prevent kswapd from going to sleep until there are processes waiting on the pfmemalloc_wait queue, and a process waiting on a queue is guaranteed to be removed from the queue only when it gets scheduled. This was done to make sure that no process is left sleeping on pfmemalloc_wait when kswapd itself goes to sleep. However, it isn't necessary to postpone kswapd sleep until the pfmemalloc_wait queue actually empties. To prevent processes from being left sleeping, it's actually enough to guarantee that all processes waiting on pfmemalloc_wait queue have been woken up by the time we put kswapd to sleep. This patch therefore fixes this issue by substituting 'wake_up' with 'wake_up_all' and removing 'return false' in the code snippet from prepare_kswapd_sleep() above. Note that if any process puts itself in the queue after this waitqueue_active() check, or after the wake up itself, it means that the process will also wake up kswapd - and since we are under prepare_to_wait(), the wake up won't be missed. Also we update the comment prepare_kswapd_sleep() to hopefully more clearly describe the races it is preventing. Fixes: 5515061d22f0 ("mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Cc: <stable@vger.kernel.org> [3.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
6b4f7799 |
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12-Dec-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: invoke slab shrinkers from shrink_zone() The slab shrinkers are currently invoked from the zonelist walkers in kswapd, direct reclaim, and zone reclaim, all of which roughly gauge the eligible LRU pages and assemble a nodemask to pass to NUMA-aware shrinkers, which then again have to walk over the nodemask. This is redundant code, extra runtime work, and fairly inaccurate when it comes to the estimation of actually scannable LRU pages. The code duplication will only get worse when making the shrinkers cgroup-aware and requiring them to have out-of-band cgroup hierarchy walks as well. Instead, invoke the shrinkers from shrink_zone(), which is where all reclaimers end up, to avoid this duplication. Take the count for eligible LRU pages out of get_scan_count(), which considers many more factors than just the availability of swap space, like zone_reclaimable_pages() currently does. Accumulate the number over all visited lruvecs to get the per-zone value. Some nodes have multiple zones due to memory addressing restrictions. To avoid putting too much pressure on the shrinkers, only invoke them once for each such node, using the class zone of the allocation as the pivot zone. For now, this integrates the slab shrinking better into the reclaim logic and gets rid of duplicative invocations from kswapd, direct reclaim, and zone reclaim. It also prepares for cgroup-awareness, allowing memcg-capable shrinkers to be added at the lruvec level without much duplication of both code and runtime work. This changes kswapd behavior, which used to invoke the shrinkers for each zone, but with scan ratios gathered from the entire node, resulting in meaningless pressure quantities on multi-zone nodes. Zone reclaim behavior also changes. It used to shrink slabs until the same amount of pages were shrunk as were reclaimed from the LRUs. Now it merely invokes the shrinkers once with the zone's scan ratio, which makes the shrinkers go easier on caches that implement aging and would prefer feeding back pressure from recently used slab objects to unused LRU pages. [vdavydov@parallels.com: assure class zone is populated] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ebff3980 |
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10-Dec-2014 |
Vlastimil Babka <vbabka@suse.cz> |
mm, compaction: pass classzone_idx and alloc_flags to watermark checking Compaction relies on zone watermark checks for decisions such as if it's worth to start compacting in compaction_suitable() or whether compaction should stop in compact_finished(). The watermark checks take classzone_idx and alloc_flags parameters, which are related to the memory allocation request. But from the context of compaction they are currently passed as 0, including the direct compaction which is invoked to satisfy the allocation request, and could therefore know the proper values. The lack of proper values can lead to mismatch between decisions taken during compaction and decisions related to the allocation request. Lack of proper classzone_idx value means that lowmem_reserve is not taken into account. This has manifested (during recent changes to deferred compaction) when DMA zone was used as fallback for preferred Normal zone. compaction_suitable() without proper classzone_idx would think that the watermarks are already satisfied, but watermark check in get_page_from_freelist() would fail. Because of this problem, deferring compaction has extra complexity that can be removed in the following patch. The issue (not confirmed in practice) with missing alloc_flags is opposite in nature. For allocations that include ALLOC_HIGH, ALLOC_HIGHER or ALLOC_CMA in alloc_flags (the last includes all MOVABLE allocations on CMA-enabled systems) the watermark checking in compaction with 0 passed will be stricter than in get_page_from_freelist(). In these cases compaction might be running for a longer time than is really needed. Another issue compaction_suitable() is that the check for "does the zone need compaction at all?" comes only after the check "does the zone have enough free free pages to succeed compaction". The latter considers extra pages for migration and can therefore in some situations fail and return COMPACT_SKIPPED, although the high-order allocation would succeed and we should return COMPACT_PARTIAL. This patch fixes these problems by adding alloc_flags and classzone_idx to struct compact_control and related functions involved in direct compaction and watermark checking. Where possible, all other callers of compaction_suitable() pass proper values where those are known. This is currently limited to classzone_idx, which is sometimes known in kswapd context. However, the direct reclaim callers should_continue_reclaim() and compaction_ready() do not currently know the proper values, so the coordination between reclaim and compaction may still not be as accurate as it could. This can be fixed later, if it's shown to be an issue. Additionaly the checks in compact_suitable() are reordered to address the second issue described above. The effect of this patch should be slightly better high-order allocation success rates and/or less compaction overhead, depending on the type of allocations and presence of CMA. It allows simplifying deferred compaction code in a followup patch. When testing with stress-highalloc, there was some slight improvement (which might be just due to variance) in success rates of non-THP-like allocations. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Christoph Lameter <cl@linux.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1da58ee2 |
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10-Dec-2014 |
Jamie Liu <jamieliu@google.com> |
mm: vmscan: count only dirty pages as congested shrink_page_list() counts all pages with a mapping, including clean pages, toward nr_congested if they're on a write-congested BDI. shrink_inactive_list() then sets ZONE_CONGESTED if nr_dirty == nr_congested. Fix this apples-to-oranges comparison by only counting pages for nr_congested if they count for nr_dirty. Signed-off-by: Jamie Liu <jamieliu@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8612c663 |
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10-Dec-2014 |
Pintu Kumar <pintu.k@samsung.com> |
mm/vmscan.c: replace printk with pr_err This patch replaces printk(KERN_ERR..) with pr_err found under shrink_slab. Thus it also reduces one line extra because of formatting. Signed-off-by: Pintu Kumar <pintu.k@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
344736f2 |
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20-Oct-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
cpuset: simplify cpuset_node_allowed API Current cpuset API for checking if a zone/node is allowed to allocate from looks rather awkward. We have hardwall and softwall versions of cpuset_node_allowed with the softwall version doing literally the same as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags. If it isn't, the softwall version may check the given node against the enclosing hardwall cpuset, which it needs to take the callback lock to do. Such a distinction was introduced by commit 02a0e53d8227 ("cpuset: rework cpuset_zone_allowed api"). Before, we had the only version with the __GFP_HARDWALL flag determining its behavior. The purpose of the commit was to avoid sleep-in-atomic bugs when someone would mistakenly call the function without the __GFP_HARDWALL flag for an atomic allocation. The suffixes introduced were intended to make the callers think before using the function. However, since the callback lock was converted from mutex to spinlock by the previous patch, the softwall check function cannot sleep, and these precautions are no longer necessary. So let's simplify the API back to the single check. Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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#
b70a2a21 |
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09-Oct-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: fix transparent huge page allocations under pressure In a memcg with even just moderate cache pressure, success rates for transparent huge page allocations drop to zero, wasting a lot of effort that the allocator puts into assembling these pages. The reason for this is that the memcg reclaim code was never designed for higher-order charges. It reclaims in small batches until there is room for at least one page. Huge page charges only succeed when these batches add up over a series of huge faults, which is unlikely under any significant load involving order-0 allocations in the group. Remove that loop on the memcg side in favor of passing the actual reclaim goal to direct reclaim, which is already set up and optimized to meet higher-order goals efficiently. This brings memcg's THP policy in line with the system policy: if the allocator painstakingly assembles a hugepage, memcg will at least make an honest effort to charge it. As a result, transparent hugepage allocation rates amid cache activity are drastically improved: vanilla patched pgalloc 4717530.80 ( +0.00%) 4451376.40 ( -5.64%) pgfault 491370.60 ( +0.00%) 225477.40 ( -54.11%) pgmajfault 2.00 ( +0.00%) 1.80 ( -6.67%) thp_fault_alloc 0.00 ( +0.00%) 531.60 (+100.00%) thp_fault_fallback 749.00 ( +0.00%) 217.40 ( -70.88%) [ Note: this may in turn increase memory consumption from internal fragmentation, which is an inherent risk of transparent hugepages. Some setups may have to adjust the memcg limits accordingly to accomodate this - or, if the machine is already packed to capacity, disable the transparent huge page feature. ] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Dave Hansen <dave@sr71.net> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
57054651 |
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09-Oct-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: clean up zone flags Page reclaim tests zone_is_reclaim_dirty(), but the site that actually sets this state does zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY), sending the reader through layers indirection just to track down a simple bit. Remove all zone flag wrappers and just use bitops against zone->flags directly. It's just as readable and the lines are barely any longer. Also rename ZONE_TAIL_LRU_DIRTY to ZONE_DIRTY to match ZONE_WRITEBACK, and remove the zone_flags_t typedef. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1f13ae39 |
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09-Oct-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: remove noisy remainder of the scan_unevictable interface The deprecation warnings for the scan_unevictable interface triggers by scripts doing `sysctl -a | grep something else'. This is annoying and not helpful. The interface has been defunct since 264e56d8247e ("mm: disable user interface to manually rescue unevictable pages"), which was in 2011, and there haven't been any reports of usecases for it, only reports that the deprecation warnings are annying. It's unlikely that anybody is using this interface specifically at this point, so remove it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
53853e2d |
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09-Oct-2014 |
Vlastimil Babka <vbabka@suse.cz> |
mm, compaction: defer each zone individually instead of preferred zone When direct sync compaction is often unsuccessful, it may become deferred for some time to avoid further useless attempts, both sync and async. Successful high-order allocations un-defer compaction, while further unsuccessful compaction attempts prolong the compaction deferred period. Currently the checking and setting deferred status is performed only on the preferred zone of the allocation that invoked direct compaction. But compaction itself is attempted on all eligible zones in the zonelist, so the behavior is suboptimal and may lead both to scenarios where 1) compaction is attempted uselessly, or 2) where it's not attempted despite good chances of succeeding, as shown on the examples below: 1) A direct compaction with Normal preferred zone failed and set deferred compaction for the Normal zone. Another unrelated direct compaction with DMA32 as preferred zone will attempt to compact DMA32 zone even though the first compaction attempt also included DMA32 zone. In another scenario, compaction with Normal preferred zone failed to compact Normal zone, but succeeded in the DMA32 zone, so it will not defer compaction. In the next attempt, it will try Normal zone which will fail again, instead of skipping Normal zone and trying DMA32 directly. 2) Kswapd will balance DMA32 zone and reset defer status based on watermarks looking good. A direct compaction with preferred Normal zone will skip compaction of all zones including DMA32 because Normal was still deferred. The allocation might have succeeded in DMA32, but won't. This patch makes compaction deferring work on individual zone basis instead of preferred zone. For each zone, it checks compaction_deferred() to decide if the zone should be skipped. If watermarks fail after compacting the zone, defer_compaction() is called. The zone where watermarks passed can still be deferred when the allocation attempt is unsuccessful. When allocation is successful, compaction_defer_reset() is called for the zone containing the allocated page. This approach should approximate calling defer_compaction() only on zones where compaction was attempted and did not yield allocated page. There might be corner cases but that is inevitable as long as the decision to stop compacting dues not guarantee that a page will be allocated. Due to a new COMPACT_DEFERRED return value, some functions relying implicitly on COMPACT_SKIPPED = 0 had to be updated, with comments made more accurate. The did_some_progress output parameter of __alloc_pages_direct_compact() is removed completely, as the caller actually does not use it after compaction sets it - it is only considered when direct reclaim sets it. During testing on a two-node machine with a single very small Normal zone on node 1, this patch has improved success rates in stress-highalloc mmtests benchmark. The success here were previously made worse by commit 3a025760fc15 ("mm: page_alloc: spill to remote nodes before waking kswapd") as kswapd was no longer resetting often enough the deferred compaction for the Normal zone, and DMA32 zones on both nodes were thus not considered for compaction. On different machine, success rates were improved with __GFP_NO_KSWAPD allocations. [akpm@linux-foundation.org: fix CONFIG_COMPACTION=n build] Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Christoph Lameter <cl@linux.com> Cc: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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747db954 |
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08-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: use page lists for uncharge batching Pages are now uncharged at release time, and all sources of batched uncharges operate on lists of pages. Directly use those lists, and get rid of the per-task batching state. This also batches statistics accounting, in addition to the res counter charges, to reduce IRQ-disabling and re-enabling. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0a31bc97 |
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08-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: rewrite uncharge API The memcg uncharging code that is involved towards the end of a page's lifetime - truncation, reclaim, swapout, migration - is impressively complicated and fragile. Because anonymous and file pages were always charged before they had their page->mapping established, uncharges had to happen when the page type could still be known from the context; as in unmap for anonymous, page cache removal for file and shmem pages, and swap cache truncation for swap pages. However, these operations happen well before the page is actually freed, and so a lot of synchronization is necessary: - Charging, uncharging, page migration, and charge migration all need to take a per-page bit spinlock as they could race with uncharging. - Swap cache truncation happens during both swap-in and swap-out, and possibly repeatedly before the page is actually freed. This means that the memcg swapout code is called from many contexts that make no sense and it has to figure out the direction from page state to make sure memory and memory+swap are always correctly charged. - On page migration, the old page might be unmapped but then reused, so memcg code has to prevent untimely uncharging in that case. Because this code - which should be a simple charge transfer - is so special-cased, it is not reusable for replace_page_cache(). But now that charged pages always have a page->mapping, introduce mem_cgroup_uncharge(), which is called after the final put_page(), when we know for sure that nobody is looking at the page anymore. For page migration, introduce mem_cgroup_migrate(), which is called after the migration is successful and the new page is fully rmapped. Because the old page is no longer uncharged after migration, prevent double charges by decoupling the page's memcg association (PCG_USED and pc->mem_cgroup) from the page holding an actual charge. The new bits PCG_MEM and PCG_MEMSW represent the respective charges and are transferred to the new page during migration. mem_cgroup_migrate() is suitable for replace_page_cache() as well, which gets rid of mem_cgroup_replace_page_cache(). However, care needs to be taken because both the source and the target page can already be charged and on the LRU when fuse is splicing: grab the page lock on the charge moving side to prevent changing pc->mem_cgroup of a page under migration. Also, the lruvecs of both pages change as we uncharge the old and charge the new during migration, and putback may race with us, so grab the lru lock and isolate the pages iff on LRU to prevent races and ensure the pages are on the right lruvec afterward. Swap accounting is massively simplified: because the page is no longer uncharged as early as swap cache deletion, a new mem_cgroup_swapout() can transfer the page's memory+swap charge (PCG_MEMSW) to the swap entry before the final put_page() in page reclaim. Finally, page_cgroup changes are now protected by whatever protection the page itself offers: anonymous pages are charged under the page table lock, whereas page cache insertions, swapin, and migration hold the page lock. Uncharging happens under full exclusion with no outstanding references. Charging and uncharging also ensure that the page is off-LRU, which serializes against charge migration. Remove the very costly page_cgroup lock and set pc->flags non-atomically. [mhocko@suse.cz: mem_cgroup_charge_statistics needs preempt_disable] [vdavydov@parallels.com: fix flags definition] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Tested-by: Jet Chen <jet.chen@intel.com> Acked-by: Michal Hocko <mhocko@suse.cz> Tested-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2ab051e1 |
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06-Aug-2014 |
Jerome Marchand <jmarchan@redhat.com> |
memcg, vmscan: Fix forced scan of anonymous pages When memory cgoups are enabled, the code that decides to force to scan anonymous pages in get_scan_count() compares global values (free, high_watermark) to a value that is restricted to a memory cgroup (file). It make the code over-eager to force anon scan. For instance, it will force anon scan when scanning a memcg that is mainly populated by anonymous page, even when there is plenty of file pages to get rid of in others memcgs, even when swappiness == 0. It breaks user's expectation about swappiness and hurts performance. This patch makes sure that forced anon scan only happens when there not enough file pages for the all zone, not just in one random memcg. [hannes@cmpxchg.org: cleanups] Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7c0db9e9 |
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06-Aug-2014 |
Jerome Marchand <jmarchan@redhat.com> |
mm, vmscan: fix an outdated comment still mentioning get_scan_ratio Quite a while ago, get_scan_ratio() has been renamed get_scan_count(), however a comment in shrink_active_list() still mention it. This patch fixes the outdated comment. Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0d5d823a |
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06-Aug-2014 |
Mel Gorman <mgorman@suse.de> |
mm: move zone->pages_scanned into a vmstat counter zone->pages_scanned is a write-intensive cache line during page reclaim and it's also updated during page free. Move the counter into vmstat to take advantage of the per-cpu updates and do not update it in the free paths unless necessary. On a small UMA machine running tiobench the difference is marginal. On a 4-node machine the overhead is more noticable. Note that automatic NUMA balancing was disabled for this test as otherwise the system CPU overhead is unpredictable. 3.16.0-rc3 3.16.0-rc3 3.16.0-rc3 vanillarearrange-v5 vmstat-v5 User 746.94 759.78 774.56 System 65336.22 58350.98 32847.27 Elapsed 27553.52 27282.02 27415.04 Note that the overhead reduction will vary depending on where exactly pages are allocated and freed. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d0480be4 |
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06-Aug-2014 |
Wang Sheng-Hui <shhuiw@gmail.com> |
mm: update the description for vm_total_pages vm_total_pages is calculated by nr_free_pagecache_pages(), which counts the number of pages which are beyond the high watermark within all zones. So vm_total_pages is not equal to total number of pages which the VM controls. Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ee814fe2 |
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06-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: clean up struct scan_control Reorder the members by input and output, then turn the individual integers for may_writepage, may_unmap, may_swap, compaction_ready, hibernation_mode into bit fields to save stack space: +72/-296 -224 kswapd 104 176 +72 try_to_free_pages 80 56 -24 try_to_free_mem_cgroup_pages 80 56 -24 shrink_all_memory 88 64 -24 reclaim_clean_pages_from_list 168 144 -24 mem_cgroup_shrink_node_zone 104 80 -24 __zone_reclaim 176 152 -24 balance_pgdat 152 - -152 Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Mel Gorman <mgorman@suse.de> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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02695175 |
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06-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: move swappiness out of scan_control Swappiness is determined for each scanned memcg individually in shrink_zone() and is not a parameter that applies throughout the reclaim scan. Move it out of struct scan_control to prevent accidental use of a stale value. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2344d7e4 |
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06-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: remove all_unreclaimable() Direct reclaim currently calls shrink_zones() to reclaim all members of a zonelist, and if that wasn't successful it does another pass through the same zonelist to check overall reclaimability. Just check reclaimability in shrink_zones() directly and propagate the result through the return value. Then remove all_unreclaimable(). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0b06496a |
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06-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: rework compaction-ready signaling in direct reclaim Page reclaim for a higher-order page runs until compaction is ready, then aborts and signals this situation through the return value of shrink_zones(). This is an oddly specific signal to encode in the return value of shrink_zones(), though, and can be quite confusing. Introduce sc->compaction_ready and signal the compactability of the zones out-of-band to free up the return value of shrink_zones() for actual zone reclaimability. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8d074293 |
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06-Aug-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: remove remains of kswapd-managed zone->all_unreclaimable shrink_zones() has a special branch to skip the all_unreclaimable() check during hibernation, because a frozen kswapd can't mark a zone unreclaimable. But ever since commit 6e543d5780e3 ("mm: vmscan: fix do_try_to_free_pages() livelock"), determining a zone to be unreclaimable is done by directly looking at its scan history and no longer relies on kswapd setting the per-zone flag. Remove this branch and let shrink_zones() check the reclaimability of the target zones regardless of hibernation state. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Cc: KOSAKI Motohiro <Kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b738d764 |
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08-Jun-2014 |
Linus Torvalds <torvalds@linux-foundation.org> |
Don't trigger congestion wait on dirty-but-not-writeout pages shrink_inactive_list() used to wait 0.1s to avoid congestion when all the pages that were isolated from the inactive list were dirty but not under active writeback. That makes no real sense, and apparently causes major interactivity issues under some loads since 3.11. The ostensible reason for it was to wait for kswapd to start writing pages, but that seems questionable as well, since the congestion wait code seems to trigger for kswapd itself as well. Also, the logic behind delaying anything when we haven't actually started writeback is not clear - it only delays actually starting that writeback. We'll still trigger the congestion waiting if (a) the process is kswapd, and we hit pages flagged for immediate reclaim (b) the process is not kswapd, and the zone backing dev writeback is actually congested. This probably needs to be revisited, but as it is this fixes a reported regression. Reported-by: Felipe Contreras <felipe.contreras@gmail.com> Pinpointed-by: Hillf Danton <dhillf@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b1de0d13 |
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06-Jun-2014 |
Mitchel Humpherys <mitchelh@codeaurora.org> |
mm: convert some level-less printks to pr_* printk is meant to be used with an associated log level. There are some instances of printk scattered around the mm code where the log level is missing. Add a log level and adhere to suggestions by scripts/checkpatch.pl by moving to the pr_* macros. Also add the typical pr_fmt definition so that print statements can be easily traced back to the modules where they occur, correlated one with another, etc. This will require the removal of some (now redundant) prefixes on a few print statements. Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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688eb988 |
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06-Jun-2014 |
Michal Hocko <mhocko@suse.cz> |
vmscan: memcg: always use swappiness of the reclaimed memcg Memory reclaim always uses swappiness of the reclaim target memcg (origin of the memory pressure) or vm_swappiness for global memory reclaim. This behavior was consistent (except for difference between global and hard limit reclaim) because swappiness was enforced to be consistent within each memcg hierarchy. After "mm: memcontrol: remove hierarchy restrictions for swappiness and oom_control" each memcg can have its own swappiness independent of hierarchical parents, though, so the consistency guarantee is gone. This can lead to an unexpected behavior. Say that a group is explicitly configured to not swapout by memory.swappiness=0 but its memory gets swapped out anyway when the memory pressure comes from its parent with a It is also unexpected that the knob is meaningless without setting the hard limit which would trigger the reclaim and enforce the swappiness. There are setups where the hard limit is configured higher in the hierarchy by an administrator and children groups are under control of somebody else who is interested in the swapout behavior but not necessarily about the memory limit. From a semantic point of view swappiness is an attribute defining anon vs. file proportional scanning of LRU which is memcg specific (unlike charges which are propagated up the hierarchy) so it should be applied to the particular memcg's LRU regardless where the memory pressure comes from. This patch removes vmscan_swappiness() and stores the swappiness into the scan_control structure. mem_cgroup_swappiness is then used to provide the correct value before shrink_lruvec is called. The global vm_swappiness is used for the root memcg. [hughd@google.com: oopses immediately when booted with cgroup_disable=memory] Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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71abdc15 |
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06-Jun-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: clear kswapd's special reclaim powers before exiting When kswapd exits, it can end up taking locks that were previously held by allocating tasks while they waited for reclaim. Lockdep currently warns about this: On Wed, May 28, 2014 at 06:06:34PM +0800, Gu Zheng wrote: > inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-R} usage. > kswapd2/1151 [HC0[0]:SC0[0]:HE1:SE1] takes: > (&sig->group_rwsem){+++++?}, at: exit_signals+0x24/0x130 > {RECLAIM_FS-ON-W} state was registered at: > mark_held_locks+0xb9/0x140 > lockdep_trace_alloc+0x7a/0xe0 > kmem_cache_alloc_trace+0x37/0x240 > flex_array_alloc+0x99/0x1a0 > cgroup_attach_task+0x63/0x430 > attach_task_by_pid+0x210/0x280 > cgroup_procs_write+0x16/0x20 > cgroup_file_write+0x120/0x2c0 > vfs_write+0xc0/0x1f0 > SyS_write+0x4c/0xa0 > tracesys+0xdd/0xe2 > irq event stamp: 49 > hardirqs last enabled at (49): _raw_spin_unlock_irqrestore+0x36/0x70 > hardirqs last disabled at (48): _raw_spin_lock_irqsave+0x2b/0xa0 > softirqs last enabled at (0): copy_process.part.24+0x627/0x15f0 > softirqs last disabled at (0): (null) > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&sig->group_rwsem); > <Interrupt> > lock(&sig->group_rwsem); > > *** DEADLOCK *** > > no locks held by kswapd2/1151. > > stack backtrace: > CPU: 30 PID: 1151 Comm: kswapd2 Not tainted 3.10.39+ #4 > Call Trace: > dump_stack+0x19/0x1b > print_usage_bug+0x1f7/0x208 > mark_lock+0x21d/0x2a0 > __lock_acquire+0x52a/0xb60 > lock_acquire+0xa2/0x140 > down_read+0x51/0xa0 > exit_signals+0x24/0x130 > do_exit+0xb5/0xa50 > kthread+0xdb/0x100 > ret_from_fork+0x7c/0xb0 This is because the kswapd thread is still marked as a reclaimer at the time of exit. But because it is exiting, nobody is actually waiting on it to make reclaim progress anymore, and it's nothing but a regular thread at this point. Be tidy and strip it of all its powers (PF_MEMALLOC, PF_SWAPWRITE, PF_KSWAPD, and the lockdep reclaim state) before returning from the thread function. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1a501907 |
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04-Jun-2014 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: use proportional scanning during direct reclaim and full scan at DEF_PRIORITY Commit "mm: vmscan: obey proportional scanning requirements for kswapd" ensured that file/anon lists were scanned proportionally for reclaim from kswapd but ignored it for direct reclaim. The intent was to minimse direct reclaim latency but Yuanhan Liu pointer out that it substitutes one long stall for many small stalls and distorts aging for normal workloads like streaming readers/writers. Hugh Dickins pointed out that a side-effect of the same commit was that when one LRU list dropped to zero that the entirety of the other list was shrunk leading to excessive reclaim in memcgs. This patch scans the file/anon lists proportionally for direct reclaim to similarly age page whether reclaimed by kswapd or direct reclaim but takes care to abort reclaim if one LRU drops to zero after reclaiming the requested number of pages. Based on ext4 and using the Intel VM scalability test 3.15.0-rc5 3.15.0-rc5 shrinker proportion Unit lru-file-readonce elapsed 5.3500 ( 0.00%) 5.4200 ( -1.31%) Unit lru-file-readonce time_range 0.2700 ( 0.00%) 0.1400 ( 48.15%) Unit lru-file-readonce time_stddv 0.1148 ( 0.00%) 0.0536 ( 53.33%) Unit lru-file-readtwice elapsed 8.1700 ( 0.00%) 8.1700 ( 0.00%) Unit lru-file-readtwice time_range 0.4300 ( 0.00%) 0.2300 ( 46.51%) Unit lru-file-readtwice time_stddv 0.1650 ( 0.00%) 0.0971 ( 41.16%) The test cases are running multiple dd instances reading sparse files. The results are within the noise for the small test machine. The impact of the patch is more noticable from the vmstats 3.15.0-rc5 3.15.0-rc5 shrinker proportion Minor Faults 35154 36784 Major Faults 611 1305 Swap Ins 394 1651 Swap Outs 4394 5891 Allocation stalls 118616 44781 Direct pages scanned 4935171 4602313 Kswapd pages scanned 15921292 16258483 Kswapd pages reclaimed 15913301 16248305 Direct pages reclaimed 4933368 4601133 Kswapd efficiency 99% 99% Kswapd velocity 670088.047 682555.961 Direct efficiency 99% 99% Direct velocity 207709.217 193212.133 Percentage direct scans 23% 22% Page writes by reclaim 4858.000 6232.000 Page writes file 464 341 Page writes anon 4394 5891 Note that there are fewer allocation stalls even though the amount of direct reclaim scanning is very approximately the same. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> Cc: Bob Liu <bob.liu@oracle.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4be89a34 |
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04-Jun-2014 |
Jianyu Zhan <nasa4836@gmail.com> |
mm/vmscan.c: use DIV_ROUND_UP for calculation of zone's balance_gap and correct comments. Currently, we use (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / KSWAPD_ZONE_BALANCE_GAP_RATIO to avoid a zero gap value. It's better to use DIV_ROUND_UP macro for neater code and clear meaning. Besides, the gap value is calculated against the per-zone "managed pages", not "present pages". This patch also corrects the comment and do some rephrasing. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b745bc85 |
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04-Jun-2014 |
Mel Gorman <mgorman@suse.de> |
mm: page_alloc: convert hot/cold parameter and immediate callers to bool cold is a bool, make it one. Make the likely case the "if" part of the block instead of the else as according to the optimisation manual this is preferred. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
df9024a8 |
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04-Jun-2014 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm: shrinker: add nid to tracepoint output Now that we are doing NUMA-aware shrinking, and can have shrinkers running in parallel, or working on individual nodes, it seems like we should also be sticking the node in the output. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Dave Chinner <david@fromorbit.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7fe70475 |
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04-Jun-2014 |
Dave Hansen <dave.hansen@linux.intel.com> |
mm: shrinker trace points: fix negatives I was looking at a trace of the slab shrinkers (attachment in this comment): https://bugs.freedesktop.org/show_bug.cgi?id=72742#c67 and noticed that "total_scan" can go negative in some cases. We used to dump out the "total_scan" variable directly, but some of the shrinker modifications along the way changed that. This patch just dumps it out directly, again. It doesn't make any sense to derive it from new_nr and nr any more since there are now other shrinkers that can be running in parallel and mucking with those values. Here's an example of the negative numbers in the output: > kswapd0-840 [000] 160.869398: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 10 new scan count 39 total_scan 29 last shrinker return val 256 > kswapd0-840 [000] 160.869618: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 39 new scan count 102 total_scan 63 last shrinker return val 256 > kswapd0-840 [000] 160.870031: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 102 new scan count 47 total_scan -55 last shrinker return val 768 > kswapd0-840 [000] 160.870464: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 47 new scan count 45 total_scan -2 last shrinker return val 768 > kswapd0-840 [000] 163.384144: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 45 new scan count 56 total_scan 11 last shrinker return val 0 > kswapd0-840 [000] 163.384297: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 56 new scan count 15 total_scan -41 last shrinker return val 256 > kswapd0-840 [000] 163.384414: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 15 new scan count 117 total_scan 102 last shrinker return val 0 > kswapd0-840 [000] 163.384657: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 117 new scan count 36 total_scan -81 last shrinker return val 512 > kswapd0-840 [000] 163.384880: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 36 new scan count 111 total_scan 75 last shrinker return val 256 > kswapd0-840 [000] 163.385256: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 111 new scan count 34 total_scan -77 last shrinker return val 768 > kswapd0-840 [000] 163.385598: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 34 new scan count 122 total_scan 88 last shrinker return val 512 Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Dave Chinner <david@fromorbit.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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399ba0b9 |
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04-Jun-2014 |
NeilBrown <neilb@suse.de> |
mm/vmscan.c: avoid throttling reclaim for loop-back nfsd threads When a loopback NFS mount is active and the backing device for the NFS mount becomes congested, that can impose throttling delays on the nfsd threads. These delays significantly reduce throughput and so the NFS mount remains congested. This results in a livelock and the reduced throughput persists. This livelock has been found in testing with the 'wait_iff_congested' call, and could possibly be caused by the 'congestion_wait' call. This livelock is similar to the deadlock which justified the introduction of PF_LESS_THROTTLE, and the same flag can be used to remove this livelock. To minimise the impact of the change, we still throttle nfsd when the filesystem it is writing to is congested, but not when some separate filesystem (e.g. the NFS filesystem) is congested. Signed-off-by: NeilBrown <neilb@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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675becce |
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04-Jun-2014 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not throttle based on pfmemalloc reserves if node has no ZONE_NORMAL throttle_direct_reclaim() is meant to trigger during swap-over-network during which the min watermark is treated as a pfmemalloc reserve. It throttes on the first node in the zonelist but this is flawed. The user-visible impact is that a process running on CPU whose local memory node has no ZONE_NORMAL will stall for prolonged periods of time, possibly indefintely. This is due to throttle_direct_reclaim thinking the pfmemalloc reserves are depleted when in fact they don't exist on that node. On a NUMA machine running a 32-bit kernel (I know) allocation requests from CPUs on node 1 would detect no pfmemalloc reserves and the process gets throttled. This patch adjusts throttling of direct reclaim to throttle based on the first node in the zonelist that has a usable ZONE_NORMAL or lower zone. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bfc8c901 |
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04-Jun-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mem-hotplug: implement get/put_online_mems kmem_cache_{create,destroy,shrink} need to get a stable value of cpu/node online mask, because they init/destroy/access per-cpu/node kmem_cache parts, which can be allocated or destroyed on cpu/mem hotplug. To protect against cpu hotplug, these functions use {get,put}_online_cpus. However, they do nothing to synchronize with memory hotplug - taking the slab_mutex does not eliminate the possibility of race as described in patch 2. What we need there is something like get_online_cpus, but for memory. We already have lock_memory_hotplug, which serves for the purpose, but it's a bit of a hammer right now, because it's backed by a mutex. As a result, it imposes some limitations to locking order, which are not desirable, and can't be used just like get_online_cpus. That's why in patch 1 I substitute it with get/put_online_mems, which work exactly like get/put_online_cpus except they block not cpu, but memory hotplug. [ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by myself, because it used an rw semaphore for get/put_online_mems, making them dead lock prune. ] This patch (of 2): {un}lock_memory_hotplug, which is used to synchronize against memory hotplug, is currently backed by a mutex, which makes it a bit of a hammer - threads that only want to get a stable value of online nodes mask won't be able to proceed concurrently. Also, it imposes some strong locking ordering rules on it, which narrows down the set of its usage scenarios. This patch introduces get/put_online_mems, which are the same as get/put_online_cpus, but for memory hotplug, i.e. executing a code inside a get/put_online_mems section will guarantee a stable value of online nodes, present pages, etc. lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6f04f48d |
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04-Jun-2014 |
Suleiman Souhlal <suleiman@google.com> |
mm: only force scan in reclaim when none of the LRUs are big enough. Prior to this change, we would decide whether to force scan a LRU during reclaim if that LRU itself was too small for the current priority. However, this can lead to the file LRU getting force scanned even if there are a lot of anonymous pages we can reclaim, leading to hot file pages getting needlessly reclaimed. To address this, we instead only force scan when none of the reclaimable LRUs are big enough. Gives huge improvements with zswap. For example, when doing -j20 kernel build in a 500MB container with zswap enabled, runtime (in seconds) is greatly reduced: x without this change + with this change N Min Max Median Avg Stddev x 5 700.997 790.076 763.928 754.05 39.59493 + 5 141.634 197.899 155.706 161.9 21.270224 Difference at 95.0% confidence -592.15 +/- 46.3521 -78.5293% +/- 6.14709% (Student's t, pooled s = 31.7819) Should also give some improvements in regular (non-zswap) swap cases. Yes, hughd found significant speedup using regular swap, with several memcgs under pressure; and it should also be effective in the non-memcg case, whenever one or another zone LRU is forced too small. Signed-off-by: Suleiman Souhlal <suleiman@google.com> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com> Cc: Seth Jennings <sjennings@variantweb.net> Cc: Bob Liu <bob.liu@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Luigi Semenzato <semenzato@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8174202b |
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03-Apr-2014 |
Al Viro <viro@zeniv.linux.org.uk> |
write_iter variants of {__,}generic_file_aio_write() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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62376251 |
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06-May-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
revert "mm: vmscan: do not swap anon pages just because free+file is low" This reverts commit 0bf1457f0cfc ("mm: vmscan: do not swap anon pages just because free+file is low") because it introduced a regression in mostly-anonymous workloads, where reclaim would become ineffective and trap every allocating task in direct reclaim. The problem is that there is a runaway feedback loop in the scan balance between file and anon, where the balance tips heavily towards a tiny thrashing file LRU and anonymous pages are no longer being looked at. The commit in question removed the safe guard that would detect such situations and respond with forced anonymous reclaim. This commit was part of a series to fix premature swapping in loads with relatively little cache, and while it made a small difference, the cure is obviously worse than the disease. Revert it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Rafael Aquini <aquini@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: <stable@kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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83da7510 |
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18-Apr-2014 |
Christoph Lameter <cl@linux.com> |
vmscan: reclaim_clean_pages_from_list() must use mod_zone_page_state() Seems to be called with preemption enabled. Therefore it must use mod_zone_page_state instead. Signed-off-by: Christoph Lameter <cl@linux.com> Reported-by: Grygorii Strashko <grygorii.strashko@ti.com> Tested-by: Grygorii Strashko <grygorii.strashko@ti.com> Cc: Tejun Heo <tj@kernel.org> Cc: Santosh Shilimkar <santosh.shilimkar@ti.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0bf1457f |
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08-Apr-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: do not swap anon pages just because free+file is low Page reclaim force-scans / swaps anonymous pages when file cache drops below the high watermark of a zone in order to prevent what little cache remains from thrashing. However, on bigger machines the high watermark value can be quite large and when the workload is dominated by a static anonymous/shmem set, the file set might just be a small window of used-once cache. In such situations, the VM starts swapping heavily when instead it should be recycling the no longer used cache. This is a longer-standing problem, but it's more likely to trigger after commit 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy") because file pages can no longer accumulate in a single zone and are dispersed into smaller fractions among the available zones. To resolve this, do not force scan anon when file pages are low but instead rely on the scan/rotation ratios to make the right prediction. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rafael Aquini <aquini@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: <stable@kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9bbc04ee |
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07-Apr-2014 |
Weijie Yang <weijie.yang@samsung.com> |
mm/vmscan: do not check compaction_ready on promoted zones We abort direct reclaim if we find the zone is ready for compaction. Sometimes the zone is just a promoted highmem zone to force a scan of highmem, which is not the intended zone the caller want to allocate a page from. In this situation, setting aborted_reclaim to indicate the caller turned back to retry the allocation is waste of time and could cause a loop in __alloc_pages_slowpath(). This patch does not check compaction_ready() on promoted zones to avoid the above situation. Only set aborted_reclaim if the caller intended zone is ready for compaction. Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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619d0d76 |
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07-Apr-2014 |
Weijie Yang <weijie.yang@samsung.com> |
mm/vmscan: restore sc->gfp_mask after promoting it to __GFP_HIGHMEM We promote sc->gfp_mask to __GFP_HIGHMEM to forcibly scan highmem if there are too many buffer_heads pinning highmem. See cc715d99e5 ("mm: vmscan: forcibly scan highmem if there are too many buffer_heads pinning highmem"). This patch restores sc->gfp_mask to its caller original value after finishing the scan job, to avoid the impact on other invocations from its upper caller, such as vmpressure_prio(), shrink_slab(). Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a528910e |
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03-Apr-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: thrash detection-based file cache sizing The VM maintains cached filesystem pages on two types of lists. One list holds the pages recently faulted into the cache, the other list holds pages that have been referenced repeatedly on that first list. The idea is to prefer reclaiming young pages over those that have shown to benefit from caching in the past. We call the recently usedbut ultimately was not significantly better than a FIFO policy and still thrashed cache based on eviction speed, rather than actual demand for cache. This patch solves one half of the problem by decoupling the ability to detect working set changes from the inactive list size. By maintaining a history of recently evicted file pages it can detect frequently used pages with an arbitrarily small inactive list size, and subsequently apply pressure on the active list based on actual demand for cache, not just overall eviction speed. Every zone maintains a counter that tracks inactive list aging speed. When a page is evicted, a snapshot of this counter is stored in the now-empty page cache radix tree slot. On refault, the minimum access distance of the page can be assessed, to evaluate whether the page should be part of the active list or not. This fixes the VM's blindness towards working set changes in excess of the inactive list. And it's the foundation to further improve the protection ability and reduce the minimum inactive list size of 50%. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Bob Liu <bob.liu@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Metin Doslu <metin@citusdata.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ozgun Erdogan <ozgun@citusdata.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <klamm@yandex-team.ru> Cc: Ryan Mallon <rmallon@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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91b0abe3 |
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03-Apr-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm + fs: store shadow entries in page cache Reclaim will be leaving shadow entries in the page cache radix tree upon evicting the real page. As those pages are found from the LRU, an iput() can lead to the inode being freed concurrently. At this point, reclaim must no longer install shadow pages because the inode freeing code needs to ensure the page tree is really empty. Add an address_space flag, AS_EXITING, that the inode freeing code sets under the tree lock before doing the final truncate. Reclaim will check for this flag before installing shadow pages. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bob Liu <bob.liu@oracle.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Metin Doslu <metin@citusdata.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ozgun Erdogan <ozgun@citusdata.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <klamm@yandex-team.ru> Cc: Ryan Mallon <rmallon@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d5bc5fd3 |
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03-Apr-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: shrink_slab: rename max_pass -> freeable The name `max_pass' is misleading, because this variable actually keeps the estimate number of freeable objects, not the maximal number of objects we can scan in this pass, which can be twice that. Rename it to reflect its actual meaning. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3115cd91 |
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03-Apr-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: remove shrink_control arg from do_try_to_free_pages() There is no need passing on a shrink_control struct from try_to_free_pages() and friends to do_try_to_free_pages() and then to shrink_zones(), because it is only used in shrink_zones() and the only field initialized on the top level is gfp_mask, which is always equal to scan_control.gfp_mask. So let's move shrink_control initialization to shrink_zones(). Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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65ec02cb |
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03-Apr-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: move call to shrink_slab() to shrink_zones() This reduces the indentation level of do_try_to_free_pages() and removes extra loop over all eligible zones counting the number of on-LRU pages. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Reviewed-by: Glauber Costa <glommer@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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99120b77 |
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03-Apr-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: respect NUMA policy mask when shrinking slab on direct reclaim When direct reclaim is executed by a process bound to a set of NUMA nodes, we should scan only those nodes when possible, but currently we will scan kmem from all online nodes even if the kmem shrinker is NUMA aware. That said, binding a process to a particular NUMA node won't prevent it from shrinking inode/dentry caches from other nodes, which is not good. Fix this. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a1c3bfb2 |
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29-Jan-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm/page-writeback.c: do not count anon pages as dirtyable memory The VM is currently heavily tuned to avoid swapping. Whether that is good or bad is a separate discussion, but as long as the VM won't swap to make room for dirty cache, we can not consider anonymous pages when calculating the amount of dirtyable memory, the baseline to which dirty_background_ratio and dirty_ratio are applied. A simple workload that occupies a significant size (40+%, depending on memory layout, storage speeds etc.) of memory with anon/tmpfs pages and uses the remainder for a streaming writer demonstrates this problem. In that case, the actual cache pages are a small fraction of what is considered dirtyable overall, which results in an relatively large portion of the cache pages to be dirtied. As kswapd starts rotating these, random tasks enter direct reclaim and stall on IO. Only consider free pages and file pages dirtyable. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ec97097b |
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23-Jan-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: call NUMA-unaware shrinkers irrespective of nodemask If a shrinker is not NUMA-aware, shrink_slab() should call it exactly once with nid=0, but currently it is not true: if node 0 is not set in the nodemask or if it is not online, we will not call such shrinkers at all. As a result some slabs will be left untouched under some circumstances. Let us fix it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Reported-by: Dave Chinner <dchinner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0b1fb40a |
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23-Jan-2014 |
Vladimir Davydov <vdavydov.dev@gmail.com> |
mm: vmscan: shrink all slab objects if tight on memory When reclaiming kmem, we currently don't scan slabs that have less than batch_size objects (see shrink_slab_node()): while (total_scan >= batch_size) { shrinkctl->nr_to_scan = batch_size; shrinker->scan_objects(shrinker, shrinkctl); total_scan -= batch_size; } If there are only a few shrinkers available, such a behavior won't cause any problems, because the batch_size is usually small, but if we have a lot of slab shrinkers, which is perfectly possible since FS shrinkers are now per-superblock, we can end up with hundreds of megabytes of practically unreclaimable kmem objects. For instance, mounting a thousand of ext2 FS images with a hundred of files in each and iterating over all the files using du(1) will result in about 200 Mb of FS caches that cannot be dropped even with the aid of the vm.drop_caches sysctl! This problem was initially pointed out by Glauber Costa [*]. Glauber proposed to fix it by making the shrink_slab() always take at least one pass, to put it simply, turning the scan loop above to a do{}while() loop. However, this proposal was rejected, because it could result in more aggressive and frequent slab shrinking even under low memory pressure when total_scan is naturally very small. This patch is a slightly modified version of Glauber's approach. Similarly to Glauber's patch, it makes shrink_slab() scan less than batch_size objects, but only if the total number of objects we want to scan (total_scan) is greater than the total number of objects available (max_pass). Since total_scan is biased as half max_pass if the current delta change is small: if (delta < max_pass / 4) total_scan = min(total_scan, max_pass / 2); this is only possible if we are scanning at high prio. That said, this patch shouldn't change the vmscan behaviour if the memory pressure is low, but if we are tight on memory, we will do our best by trying to reclaim all available objects, which sounds reasonable. [*] http://www.spinics.net/lists/cgroups/msg06913.html Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
309381fea |
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23-Jan-2014 |
Sasha Levin <sasha.levin@oracle.com> |
mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE Most of the VM_BUG_ON assertions are performed on a page. Usually, when one of these assertions fails we'll get a BUG_ON with a call stack and the registers. I've recently noticed based on the requests to add a small piece of code that dumps the page to various VM_BUG_ON sites that the page dump is quite useful to people debugging issues in mm. This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what VM_BUG_ON() does, also dumps the page before executing the actual BUG_ON. [akpm@linux-foundation.org: fix up includes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ae393321 |
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16-Oct-2013 |
Andrew Vagin <avagin@openvz.org> |
mm/vmscan.c: don't forget to free shrinker->nr_deferred This leak was added by commit 1d3d4437eae1 ("vmscan: per-node deferred work"). unreferenced object 0xffff88006ada3bd0 (size 8): comm "criu", pid 14781, jiffies 4295238251 (age 105.641s) hex dump (first 8 bytes): 00 00 00 00 00 00 00 00 ........ backtrace: [<ffffffff8170caee>] kmemleak_alloc+0x5e/0xc0 [<ffffffff811c0527>] __kmalloc+0x247/0x310 [<ffffffff8117848c>] register_shrinker+0x3c/0xa0 [<ffffffff811e115b>] sget+0x5ab/0x670 [<ffffffff812532f4>] proc_mount+0x54/0x170 [<ffffffff811e1893>] mount_fs+0x43/0x1b0 [<ffffffff81202dd2>] vfs_kern_mount+0x72/0x110 [<ffffffff81202e89>] kern_mount_data+0x19/0x30 [<ffffffff812530a0>] pid_ns_prepare_proc+0x20/0x40 [<ffffffff81083c56>] alloc_pid+0x466/0x4a0 [<ffffffff8105aeda>] copy_process+0xc6a/0x1860 [<ffffffff8105beab>] do_fork+0x8b/0x370 [<ffffffff8105c1a6>] SyS_clone+0x16/0x20 [<ffffffff8171f739>] stub_clone+0x69/0x90 [<ffffffffffffffff>] 0xffffffffffffffff Signed-off-by: Andrew Vagin <avagin@openvz.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
117aad1e |
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30-Sep-2013 |
Rafael Aquini <aquini@redhat.com> |
mm: avoid reinserting isolated balloon pages into LRU lists Isolated balloon pages can wrongly end up in LRU lists when migrate_pages() finishes its round without draining all the isolated page list. The same issue can happen when reclaim_clean_pages_from_list() tries to reclaim pages from an isolated page list, before migration, in the CMA path. Such balloon page leak opens a race window against LRU lists shrinkers that leads us to the following kernel panic: BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 IP: [<ffffffff810c2625>] shrink_page_list+0x24e/0x897 PGD 3cda2067 PUD 3d713067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 340 Comm: kswapd0 Not tainted 3.12.0-rc1-22626-g4367597 #87 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: shrink_page_list+0x24e/0x897 RSP: 0000:ffff88003da499b8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88003e82bd60 RCX: 00000000000657d5 RDX: 0000000000000000 RSI: 000000000000031f RDI: ffff88003e82bd40 RBP: ffff88003da49ab0 R08: 0000000000000001 R09: 0000000081121a45 R10: ffffffff81121a45 R11: ffff88003c4a9a28 R12: ffff88003e82bd40 R13: ffff88003da0e800 R14: 0000000000000001 R15: ffff88003da49d58 FS: 0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000067d9000 CR3: 000000003ace5000 CR4: 00000000000407b0 Call Trace: shrink_inactive_list+0x240/0x3de shrink_lruvec+0x3e0/0x566 __shrink_zone+0x94/0x178 shrink_zone+0x3a/0x82 balance_pgdat+0x32a/0x4c2 kswapd+0x2f0/0x372 kthread+0xa2/0xaa ret_from_fork+0x7c/0xb0 Code: 80 7d 8f 01 48 83 95 68 ff ff ff 00 4c 89 e7 e8 5a 7b 00 00 48 85 c0 49 89 c5 75 08 80 7d 8f 00 74 3e eb 31 48 8b 80 18 01 00 00 <48> 8b 74 0d 48 8b 78 30 be 02 00 00 00 ff d2 eb RIP [<ffffffff810c2625>] shrink_page_list+0x24e/0x897 RSP <ffff88003da499b8> CR2: 0000000000000028 ---[ end trace 703d2451af6ffbfd ]--- Kernel panic - not syncing: Fatal exception This patch fixes the issue, by assuring the proper tests are made at putback_movable_pages() & reclaim_clean_pages_from_list() to avoid isolated balloon pages being wrongly reinserted in LRU lists. [akpm@linux-foundation.org: clarify awkward comment text] Signed-off-by: Rafael Aquini <aquini@redhat.com> Reported-by: Luiz Capitulino <lcapitulino@redhat.com> Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0608f43d |
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24-Sep-2013 |
Andrew Morton <akpm@linux-foundation.org> |
revert "memcg, vmscan: integrate soft reclaim tighter with zone shrinking code" Revert commit 3b38722efd9f ("memcg, vmscan: integrate soft reclaim tighter with zone shrinking code") I merged this prematurely - Michal and Johannes still disagree about the overall design direction and the future remains unclear. Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b1aff7fc |
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24-Sep-2013 |
Andrew Morton <akpm@linux-foundation.org> |
revert "vmscan, memcg: do softlimit reclaim also for targeted reclaim" Revert commit a5b7c87f9207 ("vmscan, memcg: do softlimit reclaim also for targeted reclaim") I merged this prematurely - Michal and Johannes still disagree about the overall design direction and the future remains unclear. Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
694fbc0f |
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24-Sep-2013 |
Andrew Morton <akpm@linux-foundation.org> |
revert "memcg: enhance memcg iterator to support predicates" Revert commit de57780dc659 ("memcg: enhance memcg iterator to support predicates") I merged this prematurely - Michal and Johannes still disagree about the overall design direction and the future remains unclear. Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3120055e |
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24-Sep-2013 |
Andrew Morton <akpm@linux-foundation.org> |
revert "memcg, vmscan: do not attempt soft limit reclaim if it would not scan anything" Revert commit e839b6a1c8d0 ("memcg, vmscan: do not attempt soft limit reclaim if it would not scan anything") I merged this prematurely - Michal and Johannes still disagree about the overall design direction and the future remains unclear. Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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20ba27f5 |
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24-Sep-2013 |
Andrew Morton <akpm@linux-foundation.org> |
revert "memcg, vmscan: do not fall into reclaim-all pass too quickly" Revert commit e975de998b96 ("memcg, vmscan: do not fall into reclaim-all pass too quickly") I merged this prematurely - Michal and Johannes still disagree about the overall design direction and the future remains unclear. Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f894ffa8 |
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12-Sep-2013 |
Andrew Morton <akpm@linux-foundation.org> |
memcg: trivial cleanups Clean up some mess made by the "Soft limit rework" series, and a few other things. Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e975de99 |
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12-Sep-2013 |
Michal Hocko <mhocko@suse.cz> |
memcg, vmscan: do not fall into reclaim-all pass too quickly shrink_zone starts with soft reclaim pass first and then falls back to regular reclaim if nothing has been scanned. This behavior is natural but there is a catch. Memcg iterators, when used with the reclaim cookie, are designed to help to prevent from over reclaim by interleaving reclaimers (per node-zone-priority) so the tree walk might miss many (even all) nodes in the hierarchy e.g. when there are direct reclaimers racing with each other or with kswapd in the global case or multiple allocators reaching the limit for the target reclaim case. To make it even more complicated, targeted reclaim doesn't do the whole tree walk because it stops reclaiming once it reclaims sufficient pages. As a result groups over the limit might be missed, thus nothing is scanned, and reclaim would fall back to the reclaim all mode. This patch checks for the incomplete tree walk in shrink_zone. If no group has been visited and the hierarchy is soft reclaimable then we must have missed some groups, in which case the __shrink_zone is called again. This doesn't guarantee there will be some progress of course because the current reclaimer might be still racing with others but it would at least give a chance to start the walk without a big risk of reclaim latencies. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e839b6a1 |
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12-Sep-2013 |
Michal Hocko <mhocko@suse.cz> |
memcg, vmscan: do not attempt soft limit reclaim if it would not scan anything mem_cgroup_should_soft_reclaim controls whether soft reclaim pass is done and it always says yes currently. Memcg iterators are clever to skip nodes that are not soft reclaimable quite efficiently but mem_cgroup_should_soft_reclaim can be more clever and do not start the soft reclaim pass at all if it knows that nothing would be scanned anyway. In order to do that, simply reuse mem_cgroup_soft_reclaim_eligible for the target group of the reclaim and allow the pass only if the whole subtree wouldn't be skipped. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
de57780d |
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12-Sep-2013 |
Michal Hocko <mhocko@suse.cz> |
memcg: enhance memcg iterator to support predicates The caller of the iterator might know that some nodes or even subtrees should be skipped but there is no way to tell iterators about that so the only choice left is to let iterators to visit each node and do the selection outside of the iterating code. This, however, doesn't scale well with hierarchies with many groups where only few groups are interesting. This patch adds mem_cgroup_iter_cond variant of the iterator with a callback which gets called for every visited node. There are three possible ways how the callback can influence the walk. Either the node is visited, it is skipped but the tree walk continues down the tree or the whole subtree of the current group is skipped. [hughd@google.com: fix memcg-less page reclaim] Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a5b7c87f |
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12-Sep-2013 |
Michal Hocko <mhocko@suse.cz> |
vmscan, memcg: do softlimit reclaim also for targeted reclaim Soft reclaim has been done only for the global reclaim (both background and direct). Since "memcg: integrate soft reclaim tighter with zone shrinking code" there is no reason for this limitation anymore as the soft limit reclaim doesn't use any special code paths and it is a part of the zone shrinking code which is used by both global and targeted reclaims. From the semantic point of view it is natural to consider soft limit before touching all groups in the hierarchy tree which is touching the hard limit because soft limit tells us where to push back when there is a memory pressure. It is not important whether the pressure comes from the limit or imbalanced zones. This patch simply enables soft reclaim unconditionally in mem_cgroup_should_soft_reclaim so it is enabled for both global and targeted reclaim paths. mem_cgroup_soft_reclaim_eligible needs to learn about the root of the reclaim to know where to stop checking soft limit state of parents up the hierarchy. Say we have A (over soft limit) \ B (below s.l., hit the hard limit) / \ C D (below s.l.) B is the source of the outside memory pressure now for D but we shouldn't soft reclaim it because it is behaving well under B subtree and we can still reclaim from C (pressumably it is over the limit). mem_cgroup_soft_reclaim_eligible should therefore stop climbing up the hierarchy at B (root of the memory pressure). Signed-off-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3b38722e |
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12-Sep-2013 |
Michal Hocko <mhocko@suse.cz> |
memcg, vmscan: integrate soft reclaim tighter with zone shrinking code This patchset is sitting out of tree for quite some time without any objections. I would be really happy if it made it into 3.12. I do not want to push it too hard but I think this work is basically ready and waiting more doesn't help. The basic idea is quite simple. Pull soft reclaim into shrink_zone in the first step and get rid of the previous soft reclaim infrastructure. shrink_zone is done in two passes now. First it tries to do the soft limit reclaim and it falls back to reclaim-all mode if no group is over the limit or no pages have been scanned. The second pass happens at the same priority so the only time we waste is the memcg tree walk which has been updated in the third step to have only negligible overhead. As a bonus we will get rid of a _lot_ of code by this and soft reclaim will not stand out like before when it wasn't integrated into the zone shrinking code and it reclaimed at priority 0 (the testing results show that some workloads suffers from such an aggressive reclaim). The clean up is in a separate patch because I felt it would be easier to review that way. The second step is soft limit reclaim integration into targeted reclaim. It should be rather straight forward. Soft limit has been used only for the global reclaim so far but it makes sense for any kind of pressure coming from up-the-hierarchy, including targeted reclaim. The third step (patches 4-8) addresses the tree walk overhead by enhancing memcg iterators to enable skipping whole subtrees and tracking number of over soft limit children at each level of the hierarchy. This information is updated same way the old soft limit tree was updated (from memcg_check_events) so we shouldn't see an additional overhead. In fact mem_cgroup_update_soft_limit is much simpler than tree manipulation done previously. __shrink_zone uses mem_cgroup_soft_reclaim_eligible as a predicate for mem_cgroup_iter so the decision whether a particular group should be visited is done at the iterator level which allows us to decide to skip the whole subtree as well (if there is no child in excess). This reduces the tree walk overhead considerably. * TEST 1 ======== My primary test case was a parallel kernel build with 2 groups (make is running with -j8 with a distribution .config in a separate cgroup without any hard limit) on a 32 CPU machine booted with 1GB memory and both builds run taskset to Node 0 cpus. I was mostly interested in 2 setups. Default - no soft limit set and - and 0 soft limit set to both groups. The first one should tell us whether the rework regresses the default behavior while the second one should show us improvements in an extreme case where both workloads are always over the soft limit. /usr/bin/time -v has been used to collect the statistics and each configuration had 3 runs after fresh boot without any other load on the system. base is mmotm-2013-07-18-16-40 rework all 8 patches applied on top of base * No-limit User no-limit/base: min: 651.92 max: 672.65 avg: 664.33 std: 8.01 runs: 6 no-limit/rework: min: 657.34 [100.8%] max: 668.39 [99.4%] avg: 663.13 [99.8%] std: 3.61 runs: 6 System no-limit/base: min: 69.33 max: 71.39 avg: 70.32 std: 0.79 runs: 6 no-limit/rework: min: 69.12 [99.7%] max: 71.05 [99.5%] avg: 70.04 [99.6%] std: 0.59 runs: 6 Elapsed no-limit/base: min: 398.27 max: 422.36 avg: 408.85 std: 7.74 runs: 6 no-limit/rework: min: 386.36 [97.0%] max: 438.40 [103.8%] avg: 416.34 [101.8%] std: 18.85 runs: 6 The results are within noise. Elapsed time has a bigger variance but the average looks good. * 0-limit User 0-limit/base: min: 573.76 max: 605.63 avg: 585.73 std: 12.21 runs: 6 0-limit/rework: min: 645.77 [112.6%] max: 666.25 [110.0%] avg: 656.97 [112.2%] std: 7.77 runs: 6 System 0-limit/base: min: 69.57 max: 71.13 avg: 70.29 std: 0.54 runs: 6 0-limit/rework: min: 68.68 [98.7%] max: 71.40 [100.4%] avg: 69.91 [99.5%] std: 0.87 runs: 6 Elapsed 0-limit/base: min: 1306.14 max: 1550.17 avg: 1430.35 std: 90.86 runs: 6 0-limit/rework: min: 404.06 [30.9%] max: 465.94 [30.1%] avg: 434.81 [30.4%] std: 22.68 runs: 6 The improvement is really huge here (even bigger than with my previous testing and I suspect that this highly depends on the storage). Page fault statistics tell us at least part of the story: Minor 0-limit/base: min: 37180461.00 max: 37319986.00 avg: 37247470.00 std: 54772.71 runs: 6 0-limit/rework: min: 36751685.00 [98.8%] max: 36805379.00 [98.6%] avg: 36774506.33 [98.7%] std: 17109.03 runs: 6 Major 0-limit/base: min: 170604.00 max: 221141.00 avg: 196081.83 std: 18217.01 runs: 6 0-limit/rework: min: 2864.00 [1.7%] max: 10029.00 [4.5%] avg: 5627.33 [2.9%] std: 2252.71 runs: 6 Same as with my previous testing Minor faults are more or less within noise but Major fault count is way bellow the base kernel. While this looks as a nice win it is fair to say that 0-limit configuration is quite artificial. So I was playing with 0-no-limit loads as well. * TEST 2 ======== The following results are from 2 groups configuration on a 16GB machine (single NUMA node). - A running stream IO (dd if=/dev/zero of=local.file bs=1024) with 2*TotalMem with 0 soft limit. - B running a mem_eater which consumes TotalMem-1G without any limit. The mem_eater consumes the memory in 100 chunks with 1s nap after each mmap+poppulate so that both loads have chance to fight for the memory. The expected result is that B shouldn't be reclaimed and A shouldn't see a big dropdown in elapsed time. User base: min: 2.68 max: 2.89 avg: 2.76 std: 0.09 runs: 3 rework: min: 3.27 [122.0%] max: 3.74 [129.4%] avg: 3.44 [124.6%] std: 0.21 runs: 3 System base: min: 86.26 max: 88.29 avg: 87.28 std: 0.83 runs: 3 rework: min: 81.05 [94.0%] max: 84.96 [96.2%] avg: 83.14 [95.3%] std: 1.61 runs: 3 Elapsed base: min: 317.28 max: 332.39 avg: 325.84 std: 6.33 runs: 3 rework: min: 281.53 [88.7%] max: 298.16 [89.7%] avg: 290.99 [89.3%] std: 6.98 runs: 3 System time improved slightly as well as Elapsed. My previous testing has shown worse numbers but this again seem to depend on the storage speed. My theory is that the writeback doesn't catch up and prio-0 soft reclaim falls into wait on writeback page too often in the base kernel. The patched kernel doesn't do that because the soft reclaim is done from the kswapd/direct reclaim context. This can be seen on the following graph nicely. The A's group usage_in_bytes regurarly drops really low very often. All 3 runs http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/stream.png resp. a detail of the single run http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/stream-one-run.png mem_eater seems to be doing better as well. It gets to the full allocation size faster as can be seen on the following graph: http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/mem_eater-one-run.png /proc/meminfo collected during the test also shows that rework kernel hasn't swapped that much (well almost not at all): base: max: 123900 K avg: 56388.29 K rework: max: 300 K avg: 128.68 K kswapd and direct reclaim statistics are of no use unfortunatelly because soft reclaim is not accounted properly as the counters are hidden by global_reclaim() checks in the base kernel. * TEST 3 ======== Another test was the same configuration as TEST2 except the stream IO was replaced by a single kbuild (16 parallel jobs bound to Node0 cpus same as in TEST1) and mem_eater allocated TotalMem-200M so kbuild had only 200MB left. Kbuild did better with the rework kernel here as well: User base: min: 860.28 max: 872.86 avg: 868.03 std: 5.54 runs: 3 rework: min: 880.81 [102.4%] max: 887.45 [101.7%] avg: 883.56 [101.8%] std: 2.83 runs: 3 System base: min: 84.35 max: 85.06 avg: 84.79 std: 0.31 runs: 3 rework: min: 85.62 [101.5%] max: 86.09 [101.2%] avg: 85.79 [101.2%] std: 0.21 runs: 3 Elapsed base: min: 135.36 max: 243.30 avg: 182.47 std: 45.12 runs: 3 rework: min: 110.46 [81.6%] max: 116.20 [47.8%] avg: 114.15 [62.6%] std: 2.61 runs: 3 Minor base: min: 36635476.00 max: 36673365.00 avg: 36654812.00 std: 15478.03 runs: 3 rework: min: 36639301.00 [100.0%] max: 36695541.00 [100.1%] avg: 36665511.00 [100.0%] std: 23118.23 runs: 3 Major base: min: 14708.00 max: 53328.00 avg: 31379.00 std: 16202.24 runs: 3 rework: min: 302.00 [2.1%] max: 414.00 [0.8%] avg: 366.33 [1.2%] std: 47.22 runs: 3 Again we can see a significant improvement in Elapsed (it also seems to be more stable), there is a huge dropdown for the Major page faults and much more swapping: base: max: 583736 K avg: 112547.43 K rework: max: 4012 K avg: 124.36 K Graphs from all three runs show the variability of the kbuild quite nicely. It even seems that it took longer after every run with the base kernel which would be quite surprising as the source tree for the build is removed and caches are dropped after each run so the build operates on a freshly extracted sources everytime. http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/kbuild-mem_eater.png My other testing shows that this is just a matter of timing and other runs behave differently the std for Elapsed time is similar ~50. Example of other three runs: http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/kbuild-mem_eater2.png So to wrap this up. The series is still doing good and improves the soft limit. The testing results for bunch of cgroups with both stream IO and kbuild loads can be found in "memcg: track children in soft limit excess to improve soft limit". This patch: Memcg soft reclaim has been traditionally triggered from the global reclaim paths before calling shrink_zone. mem_cgroup_soft_limit_reclaim then picked up a group which exceeds the soft limit the most and reclaimed it with 0 priority to reclaim at least SWAP_CLUSTER_MAX pages. The infrastructure requires per-node-zone trees which hold over-limit groups and keep them up-to-date (via memcg_check_events) which is not cost free. Although this overhead hasn't turned out to be a bottle neck the implementation is suboptimal because mem_cgroup_update_tree has no idea which zones consumed memory over the limit so we could easily end up having a group on a node-zone tree having only few pages from that node-zone. This patch doesn't try to fix node-zone trees management because it seems that integrating soft reclaim into zone shrinking sounds much easier and more appropriate for several reasons. First of all 0 priority reclaim was a crude hack which might lead to big stalls if the group's LRUs are big and hard to reclaim (e.g. a lot of dirty/writeback pages). Soft reclaim should be applicable also to the targeted reclaim which is awkward right now without additional hacks. Last but not least the whole infrastructure eats quite some code. After this patch shrink_zone is done in 2 passes. First it tries to do the soft reclaim if appropriate (only for global reclaim for now to keep compatible with the original state) and fall back to ignoring soft limit if no group is eligible to soft reclaim or nothing has been scanned during the first pass. Only groups which are over their soft limit or any of their parents up the hierarchy is over the limit are considered eligible during the first pass. Soft limit tree which is not necessary anymore will be removed in the follow up patch to make this patch smaller and easier to review. Signed-off-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6e543d57 |
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11-Sep-2013 |
Lisa Du <cldu@marvell.com> |
mm: vmscan: fix do_try_to_free_pages() livelock This patch is based on KOSAKI's work and I add a little more description, please refer https://lkml.org/lkml/2012/6/14/74. Currently, I found system can enter a state that there are lots of free pages in a zone but only order-0 and order-1 pages which means the zone is heavily fragmented, then high order allocation could make direct reclaim path's long stall(ex, 60 seconds) especially in no swap and no compaciton enviroment. This problem happened on v3.4, but it seems issue still lives in current tree, the reason is do_try_to_free_pages enter live lock: kswapd will go to sleep if the zones have been fully scanned and are still not balanced. As kswapd thinks there's little point trying all over again to avoid infinite loop. Instead it changes order from high-order to 0-order because kswapd think order-0 is the most important. Look at 73ce02e9 in detail. If watermarks are ok, kswapd will go back to sleep and may leave zone->all_unreclaimable =3D 0. It assume high-order users can still perform direct reclaim if they wish. Direct reclaim continue to reclaim for a high order which is not a COSTLY_ORDER without oom-killer until kswapd turn on zone->all_unreclaimble= . This is because to avoid too early oom-kill. So it means direct_reclaim depends on kswapd to break this loop. In worst case, direct-reclaim may continue to page reclaim forever when kswapd sleeps forever until someone like watchdog detect and finally kill the process. As described in: http://thread.gmane.org/gmane.linux.kernel.mm/103737 We can't turn on zone->all_unreclaimable from direct reclaim path because direct reclaim path don't take any lock and this way is racy. Thus this patch removes zone->all_unreclaimable field completely and recalculates zone reclaimable state every time. Note: we can't take the idea that direct-reclaim see zone->pages_scanned directly and kswapd continue to use zone->all_unreclaimable. Because, it is racy. commit 929bea7c71 (vmscan: all_unreclaimable() use zone->all_unreclaimable as a name) describes the detail. [akpm@linux-foundation.org: uninline zone_reclaimable_pages() and zone_reclaimable()] Cc: Aaditya Kumar <aaditya.kumar.30@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Nick Piggin <npiggin@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux.com> Cc: Bob Liu <lliubbo@gmail.com> Cc: Neil Zhang <zhangwm@marvell.com> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Lisa Du <cldu@marvell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0ec3b74c |
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11-Sep-2013 |
Vlastimil Babka <vbabka@suse.cz> |
mm: putback_lru_page: remove unnecessary call to page_lru_base_type() The goal of this patch series is to improve performance of munlock() of large mlocked memory areas on systems without THP. This is motivated by reported very long times of crash recovery of processes with such areas, where munlock() can take several seconds. See http://lwn.net/Articles/548108/ The work was driven by a simple benchmark (to be included in mmtests) that mmaps() e.g. 56GB with MAP_LOCKED | MAP_POPULATE and measures the time of munlock(). Profiling was performed by attaching operf --pid to the process and sending a signal to trigger the munlock() part and then notify bach the monitoring wrapper to stop operf, so that only munlock() appears in the profile. The profiles have shown that CPU time is spent mostly by atomic operations and repeated locking per single pages. This series aims to reduce both, starting from simpler to more complex changes. Patch 1 performs a simple cleanup in putback_lru_page() so that page lru base type is not determined without being actually needed. Patch 2 removes an unnecessary call to lru_add_drain() which drains the per-cpu pagevec after each munlocked page is put there. Patch 3 changes munlock_vma_range() to use an on-stack pagevec for isolating multiple non-THP pages under a single lru_lock instead of locking and processing each page separately. Patch 4 changes the NR_MLOCK accounting to be called only once per the pvec introduced by previous patch. Patch 5 uses the introduced pagevec to batch also the work of putback_lru_page when possible, bypassing the per-cpu pvec and associated overhead. Patch 6 removes a redundant get_page/put_page pair which saves costly atomic operations. Patch 7 avoids calling follow_page_mask() on each individual page, and obtains multiple page references under a single page table lock where possible. Measurements were made using 3.11-rc3 as a baseline. The first set of measurements shows the possibly ideal conditions where batching should help the most. All memory is allocated from a single NUMA node and THP is disabled. timedmunlock 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 0 1 2 3 4 5 6 7 Elapsed min 3.38 ( 0.00%) 3.39 ( -0.13%) 3.00 ( 11.33%) 2.70 ( 20.20%) 2.67 ( 21.11%) 2.37 ( 29.88%) 2.20 ( 34.91%) 1.91 ( 43.59%) Elapsed mean 3.39 ( 0.00%) 3.40 ( -0.23%) 3.01 ( 11.33%) 2.70 ( 20.26%) 2.67 ( 21.21%) 2.38 ( 29.88%) 2.21 ( 34.93%) 1.92 ( 43.46%) Elapsed stddev 0.01 ( 0.00%) 0.01 (-43.09%) 0.01 ( 15.42%) 0.01 ( 23.42%) 0.00 ( 89.78%) 0.01 ( -7.15%) 0.00 ( 76.69%) 0.02 (-91.77%) Elapsed max 3.41 ( 0.00%) 3.43 ( -0.52%) 3.03 ( 11.29%) 2.72 ( 20.16%) 2.67 ( 21.63%) 2.40 ( 29.50%) 2.21 ( 35.21%) 1.96 ( 42.39%) Elapsed range 0.03 ( 0.00%) 0.04 (-51.16%) 0.02 ( 6.27%) 0.02 ( 14.67%) 0.00 ( 88.90%) 0.03 (-19.18%) 0.01 ( 73.70%) 0.06 (-113.35% The second set of measurements simulates the worst possible conditions for batching by using numactl --interleave, so that there is in fact only one page per pagevec. Even in this case the series seems to improve performance thanks to reduced atomic operations and removal of lru_add_drain(). timedmunlock 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 0 1 2 3 4 5 6 7 Elapsed min 4.00 ( 0.00%) 4.04 ( -0.93%) 3.87 ( 3.37%) 3.72 ( 6.94%) 3.81 ( 4.72%) 3.69 ( 7.82%) 3.64 ( 8.92%) 3.41 ( 14.81%) Elapsed mean 4.17 ( 0.00%) 4.15 ( 0.51%) 4.03 ( 3.49%) 3.89 ( 6.84%) 3.86 ( 7.48%) 3.89 ( 6.69%) 3.70 ( 11.27%) 3.48 ( 16.59%) Elapsed stddev 0.16 ( 0.00%) 0.08 ( 50.76%) 0.10 ( 41.58%) 0.16 ( 4.59%) 0.05 ( 72.38%) 0.19 (-12.91%) 0.05 ( 68.09%) 0.06 ( 66.03%) Elapsed max 4.34 ( 0.00%) 4.32 ( 0.56%) 4.19 ( 3.62%) 4.12 ( 5.15%) 3.91 ( 9.88%) 4.12 ( 5.25%) 3.80 ( 12.58%) 3.56 ( 18.08%) Elapsed range 0.34 ( 0.00%) 0.28 ( 17.91%) 0.32 ( 6.45%) 0.40 (-15.73%) 0.10 ( 70.06%) 0.43 (-24.84%) 0.15 ( 55.32%) 0.15 ( 56.16%) For completeness, a third set of measurements shows the situation where THP is enabled and allocations are again done on a single NUMA node. Here munlock() is already very fast thanks to huge pages, and this series does not compromise that performance. It seems that the removal of call to lru_add_drain() still helps a bit. timedmunlock 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 0 1 2 3 4 5 6 7 Elapsed min 0.01 ( 0.00%) 0.01 ( -0.11%) 0.01 ( 6.59%) 0.01 ( 5.41%) 0.01 ( 5.45%) 0.01 ( 5.03%) 0.01 ( 6.08%) 0.01 ( 5.20%) Elapsed mean 0.01 ( 0.00%) 0.01 ( -0.27%) 0.01 ( 6.39%) 0.01 ( 5.30%) 0.01 ( 5.32%) 0.01 ( 5.03%) 0.01 ( 5.97%) 0.01 ( 5.22%) Elapsed stddev 0.00 ( 0.00%) 0.00 ( -9.59%) 0.00 ( 10.77%) 0.00 ( 3.24%) 0.00 ( 24.42%) 0.00 ( 31.86%) 0.00 ( -7.46%) 0.00 ( 6.11%) Elapsed max 0.01 ( 0.00%) 0.01 ( -0.01%) 0.01 ( 6.83%) 0.01 ( 5.42%) 0.01 ( 5.79%) 0.01 ( 5.53%) 0.01 ( 6.08%) 0.01 ( 5.26%) Elapsed range 0.00 ( 0.00%) 0.00 ( 7.30%) 0.00 ( 24.38%) 0.00 ( 6.10%) 0.00 ( 30.79%) 0.00 ( 42.52%) 0.00 ( 6.11%) 0.00 ( 10.07%) This patch (of 7): In putback_lru_page() since commit c53954a092 (""mm: remove lru parameter from __lru_cache_add and lru_cache_add_lru") it is no longer needed to determine lru list via page_lru_base_type(). This patch replaces it with simple flag is_unevictable which says that the page was put on the inevictable list. This is the only information that matters in subsequent tests. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Jörn Engel <joern@logfs.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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892f795d |
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11-Sep-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: fix numa reclaim balance problem in kswapd The way the page allocator interacts with kswapd creates aging imbalances, where the amount of time a userspace page gets in memory under reclaim pressure is dependent on which zone, which node the allocator took the page frame from. #1 fixes missed kswapd wakeups on NUMA systems, which lead to some nodes falling behind for a full reclaim cycle relative to the other nodes in the system #3 fixes an interaction where kswapd and a continuous stream of page allocations keep the preferred zone of a task between the high and low watermark (allocations succeed + kswapd does not go to sleep) indefinitely, completely underutilizing the lower zones and thrashing on the preferred zone These patches are the aging fairness part of the thrash-detection based file LRU balancing. Andrea recommended to submit them separately as they are bugfixes in their own right. The following test ran a foreground workload (memcachetest) with background IO of various sizes on a 4 node 8G system (similar results were observed with single-node 4G systems): parallelio BAS FAIRALLO BASE FAIRALLOC Ops memcachetest-0M 5170.00 ( 0.00%) 5283.00 ( 2.19%) Ops memcachetest-791M 4740.00 ( 0.00%) 5293.00 ( 11.67%) Ops memcachetest-2639M 2551.00 ( 0.00%) 4950.00 ( 94.04%) Ops memcachetest-4487M 2606.00 ( 0.00%) 3922.00 ( 50.50%) Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops io-duration-791M 55.00 ( 0.00%) 18.00 ( 67.27%) Ops io-duration-2639M 235.00 ( 0.00%) 103.00 ( 56.17%) Ops io-duration-4487M 278.00 ( 0.00%) 173.00 ( 37.77%) Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-791M 245184.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-2639M 468069.00 ( 0.00%) 108778.00 ( 76.76%) Ops swaptotal-4487M 452529.00 ( 0.00%) 76623.00 ( 83.07%) Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-791M 108297.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-2639M 169537.00 ( 0.00%) 50031.00 ( 70.49%) Ops swapin-4487M 167435.00 ( 0.00%) 34178.00 ( 79.59%) Ops minorfaults-0M 1518666.00 ( 0.00%) 1503993.00 ( 0.97%) Ops minorfaults-791M 1676963.00 ( 0.00%) 1520115.00 ( 9.35%) Ops minorfaults-2639M 1606035.00 ( 0.00%) 1799717.00 (-12.06%) Ops minorfaults-4487M 1612118.00 ( 0.00%) 1583825.00 ( 1.76%) Ops majorfaults-0M 6.00 ( 0.00%) 0.00 ( 0.00%) Ops majorfaults-791M 13836.00 ( 0.00%) 10.00 ( 99.93%) Ops majorfaults-2639M 22307.00 ( 0.00%) 6490.00 ( 70.91%) Ops majorfaults-4487M 21631.00 ( 0.00%) 4380.00 ( 79.75%) BAS FAIRALLO BASE FAIRALLOC User 287.78 460.97 System 2151.67 3142.51 Elapsed 9737.00 8879.34 BAS FAIRALLO BASE FAIRALLOC Minor Faults 53721925 57188551 Major Faults 392195 15157 Swap Ins 2994854 112770 Swap Outs 4907092 134982 Direct pages scanned 0 41824 Kswapd pages scanned 32975063 8128269 Kswapd pages reclaimed 6323069 7093495 Direct pages reclaimed 0 41824 Kswapd efficiency 19% 87% Kswapd velocity 3386.573 915.414 Direct efficiency 100% 100% Direct velocity 0.000 4.710 Percentage direct scans 0% 0% Zone normal velocity 2011.338 550.661 Zone dma32 velocity 1365.623 369.221 Zone dma velocity 9.612 0.242 Page writes by reclaim 18732404.000 614807.000 Page writes file 13825312 479825 Page writes anon 4907092 134982 Page reclaim immediate 85490 5647 Sector Reads 12080532 483244 Sector Writes 88740508 65438876 Page rescued immediate 0 0 Slabs scanned 82560 12160 Direct inode steals 0 0 Kswapd inode steals 24401 40013 Kswapd skipped wait 0 0 THP fault alloc 6 8 THP collapse alloc 5481 5812 THP splits 75 22 THP fault fallback 0 0 THP collapse fail 0 0 Compaction stalls 0 54 Compaction success 0 45 Compaction failures 0 9 Page migrate success 881492 82278 Page migrate failure 0 0 Compaction pages isolated 0 60334 Compaction migrate scanned 0 53505 Compaction free scanned 0 1537605 Compaction cost 914 86 NUMA PTE updates 46738231 41988419 NUMA hint faults 31175564 24213387 NUMA hint local faults 10427393 6411593 NUMA pages migrated 881492 55344 AutoNUMA cost 156221 121361 The overall runtime was reduced, throughput for both the foreground workload as well as the background IO improved, major faults, swapping and reclaim activity shrunk significantly, reclaim efficiency more than quadrupled. This patch: When the page allocator fails to get a page from all zones in its given zonelist, it wakes up the per-node kswapds for all zones that are at their low watermark. However, with a system under load the free pages in a zone can fluctuate enough that the allocation fails but the kswapd wakeup is also skipped while the zone is still really close to the low watermark. When one node misses a wakeup like this, it won't be aged before all the other node's zones are down to their low watermarks again. And skipping a full aging cycle is an obvious fairness problem. Kswapd runs until the high watermarks are restored, so it should also be woken when the high watermarks are not met. This ages nodes more equally and creates a safety margin for the page counter fluctuation. By using zone_balanced(), it will now check, in addition to the watermark, if compaction requires more order-0 pages to create a higher order page. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Paul Bolle <paul.bollee@gmail.com> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a0b02131 |
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27-Aug-2013 |
Dave Chinner <dchinner@redhat.com> |
shrinker: Kill old ->shrink API. There are no more users of this API, so kill it dead, dead, dead and quietly bury the corpse in a shallow, unmarked grave in a dark forest deep in the hills... [glommer@openvz.org: added flowers to the grave] Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Greg Thelen <gthelen@google.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
1d3d4437 |
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27-Aug-2013 |
Glauber Costa <glommer@openvz.org> |
vmscan: per-node deferred work The list_lru infrastructure already keeps per-node LRU lists in its node-specific list_lru_node arrays and provide us with a per-node API, and the shrinkers are properly equiped with node information. This means that we can now focus our shrinking effort in a single node, but the work that is deferred from one run to another is kept global at nr_in_batch. Work can be deferred, for instance, during direct reclaim under a GFP_NOFS allocation, where situation, all the filesystem shrinkers will be prevented from running and accumulate in nr_in_batch the amount of work they should have done, but could not. This creates an impedance problem, where upon node pressure, work deferred will accumulate and end up being flushed in other nodes. The problem we describe is particularly harmful in big machines, where many nodes can accumulate at the same time, all adding to the global counter nr_in_batch. As we accumulate more and more, we start to ask for the caches to flush even bigger numbers. The result is that the caches are depleted and do not stabilize. To achieve stable steady state behavior, we need to tackle it differently. In this patch we keep the deferred count per-node, in the new array nr_deferred[] (the name is also a bit more descriptive) and will never accumulate that to other nodes. Signed-off-by: Glauber Costa <glommer@openvz.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
0ce3d744 |
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27-Aug-2013 |
Dave Chinner <dchinner@redhat.com> |
shrinker: add node awareness Pass the node of the current zone being reclaimed to shrink_slab(), allowing the shrinker control nodemask to be set appropriately for node aware shrinkers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Glauber Costa <glommer@openvz.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
24f7c6b9 |
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27-Aug-2013 |
Dave Chinner <dchinner@redhat.com> |
mm: new shrinker API The current shrinker callout API uses an a single shrinker call for multiple functions. To determine the function, a special magical value is passed in a parameter to change the behaviour. This complicates the implementation and return value specification for the different behaviours. Separate the two different behaviours into separate operations, one to return a count of freeable objects in the cache, and another to scan a certain number of objects in the cache for freeing. In defining these new operations, ensure the return values and resultant behaviours are clearly defined and documented. Modify shrink_slab() to use the new API and implement the callouts for all the existing shrinkers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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918fc718 |
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08-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not scale writeback pages when deciding whether to set ZONE_WRITEBACK After the patch "mm: vmscan: Flatten kswapd priority loop" was merged the scanning priority of kswapd changed. The priority now rises until it is scanning enough pages to meet the high watermark. shrink_inactive_list sets ZONE_WRITEBACK if a number of pages were encountered under writeback but this value is scaled based on the priority. As kswapd frequently scans with a higher priority now it is relatively easy to set ZONE_WRITEBACK. This patch removes the scaling and treates writeback pages similar to how it treats unqueued dirty pages and congested pages. The user-visible effect should be that kswapd will writeback fewer pages from reclaim context. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5a1c9cbc |
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08-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not continue scanning if reclaim was aborted for compaction Direct reclaim is not aborting to allow compaction to go ahead properly. do_try_to_free_pages is told to abort reclaim which is happily ignores and instead increases priority instead until it reaches 0 and starts shrinking file/anon equally. This patch corrects the situation by aborting reclaim when requested instead of raising priority. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c53954a0 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: remove lru parameter from __lru_cache_add and lru_cache_add_lru Similar to __pagevec_lru_add, this patch removes the LRU parameter from __lru_cache_add and lru_cache_add_lru as the caller does not control the exact LRU the page gets added to. lru_cache_add_lru gets renamed to lru_cache_add the name is silly without the lru parameter. With the parameter removed, it is required that the caller indicate if they want the page added to the active or inactive list by setting or clearing PageActive respectively. [akpm@linux-foundation.org: Suggested the patch] [gang.chen@asianux.com: fix used-unintialized warning] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b4597226 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: take page buffers dirty and locked state into account Page reclaim keeps track of dirty and under writeback pages and uses it to determine if wait_iff_congested() should stall or if kswapd should begin writing back pages. This fails to account for buffer pages that can be under writeback but not PageWriteback which is the case for filesystems like ext3 ordered mode. Furthermore, PageDirty buffer pages can have all the buffers clean and writepage does no IO so it should not be accounted as congested. This patch adds an address_space operation that filesystems may optionally use to check if a page is really dirty or really under writeback. An implementation is provided for for buffer_heads is added and used for block operations and ext3 in ordered mode. By default the page flags are obeyed. Credit goes to Jan Kara for identifying that the page flags alone are not sufficient for ext3 and sanity checking a number of ideas on how the problem could be addressed. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d04e8acd |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: treat pages marked for immediate reclaim as zone congestion Currently a zone will only be marked congested if the underlying BDI is congested but if dirty pages are spread across zones it is possible that an individual zone is full of dirty pages without being congested. The impact is that zone gets scanned very quickly potentially reclaiming really clean pages. This patch treats pages marked for immediate reclaim as congested for the purposes of marking a zone ZONE_CONGESTED and stalling in wait_iff_congested. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8e950282 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: move direct reclaim wait_iff_congested into shrink_list shrink_inactive_list makes decisions on whether to stall based on the number of dirty pages encountered. The wait_iff_congested() call in shrink_page_list does no such thing and it's arbitrary. This patch moves the decision on whether to set ZONE_CONGESTED and the wait_iff_congested call into shrink_page_list. This keeps all the decisions on whether to stall or not in the one place. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f7ab8db7 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: set zone flags before blocking In shrink_page_list a decision may be made to stall and flag a zone as ZONE_WRITEBACK so that if a large number of unqueued dirty pages are encountered later then the reclaimer will stall. Set ZONE_WRITEBACK before potentially going to sleep so it is noticed sooner. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b1a6f21e |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: stall page reclaim after a list of pages have been processed Commit "mm: vmscan: Block kswapd if it is encountering pages under writeback" blocks page reclaim if it encounters pages under writeback marked for immediate reclaim. It blocks while pages are still isolated from the LRU which is unnecessary. This patch defers the blocking until after the isolated pages have been processed and tidies up some of the comments. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e2be15f6 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: stall page reclaim and writeback pages based on dirty/writepage pages encountered Further testing of the "Reduce system disruption due to kswapd" discovered a few problems. First and foremost, it's possible for pages under writeback to be freed which will lead to badness. Second, as pages were not being swapped the file LRU was being scanned faster and clean file pages were being reclaimed. In some cases this results in increased read IO to re-read data from disk. Third, more pages were being written from kswapd context which can adversly affect IO performance. Lastly, it was observed that PageDirty pages are not necessarily dirty on all filesystems (buffers can be clean while PageDirty is set and ->writepage generates no IO) and not all filesystems set PageWriteback when the page is being written (e.g. ext3). This disconnect confuses the reclaim stalling logic. This follow-up series is aimed at these problems. The tests were based on three kernels vanilla: kernel 3.9 as that is what the current mmotm uses as a baseline mmotm-20130522 is mmotm as of 22nd May with "Reduce system disruption due to kswapd" applied on top as per what should be in Andrew's tree right now lessdisrupt-v7r10 is this follow-up series on top of the mmotm kernel The first test used memcached+memcachetest while some background IO was in progress as implemented by the parallel IO tests implement in MM Tests. memcachetest benchmarks how many operations/second memcached can service. It starts with no background IO on a freshly created ext4 filesystem and then re-runs the test with larger amounts of IO in the background to roughly simulate a large copy in progress. The expectation is that the IO should have little or no impact on memcachetest which is running entirely in memory. parallelio 3.9.0 3.9.0 3.9.0 vanilla mm1-mmotm-20130522 mm1-lessdisrupt-v7r10 Ops memcachetest-0M 23117.00 ( 0.00%) 22780.00 ( -1.46%) 22763.00 ( -1.53%) Ops memcachetest-715M 23774.00 ( 0.00%) 23299.00 ( -2.00%) 22934.00 ( -3.53%) Ops memcachetest-2385M 4208.00 ( 0.00%) 24154.00 (474.00%) 23765.00 (464.76%) Ops memcachetest-4055M 4104.00 ( 0.00%) 25130.00 (512.33%) 24614.00 (499.76%) Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops io-duration-715M 12.00 ( 0.00%) 7.00 ( 41.67%) 6.00 ( 50.00%) Ops io-duration-2385M 116.00 ( 0.00%) 21.00 ( 81.90%) 21.00 ( 81.90%) Ops io-duration-4055M 160.00 ( 0.00%) 36.00 ( 77.50%) 35.00 ( 78.12%) Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-715M 140138.00 ( 0.00%) 18.00 ( 99.99%) 18.00 ( 99.99%) Ops swaptotal-2385M 385682.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-4055M 418029.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-715M 144.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-2385M 134227.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-4055M 125618.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops minorfaults-0M 1536429.00 ( 0.00%) 1531632.00 ( 0.31%) 1533541.00 ( 0.19%) Ops minorfaults-715M 1786996.00 ( 0.00%) 1612148.00 ( 9.78%) 1608832.00 ( 9.97%) Ops minorfaults-2385M 1757952.00 ( 0.00%) 1614874.00 ( 8.14%) 1613541.00 ( 8.21%) Ops minorfaults-4055M 1774460.00 ( 0.00%) 1633400.00 ( 7.95%) 1630881.00 ( 8.09%) Ops majorfaults-0M 1.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops majorfaults-715M 184.00 ( 0.00%) 167.00 ( 9.24%) 166.00 ( 9.78%) Ops majorfaults-2385M 24444.00 ( 0.00%) 155.00 ( 99.37%) 93.00 ( 99.62%) Ops majorfaults-4055M 21357.00 ( 0.00%) 147.00 ( 99.31%) 134.00 ( 99.37%) memcachetest is the transactions/second reported by memcachetest. In the vanilla kernel note that performance drops from around 23K/sec to just over 4K/second when there is 2385M of IO going on in the background. With current mmotm, there is no collapse in performance and with this follow-up series there is little change. swaptotal is the total amount of swap traffic. With mmotm and the follow-up series, the total amount of swapping is much reduced. 3.9.0 3.9.0 3.9.0 vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10 Minor Faults 11160152 10706748 10622316 Major Faults 46305 755 678 Swap Ins 260249 0 0 Swap Outs 683860 18 18 Direct pages scanned 0 678 2520 Kswapd pages scanned 6046108 8814900 1639279 Kswapd pages reclaimed 1081954 1172267 1094635 Direct pages reclaimed 0 566 2304 Kswapd efficiency 17% 13% 66% Kswapd velocity 5217.560 7618.953 1414.879 Direct efficiency 100% 83% 91% Direct velocity 0.000 0.586 2.175 Percentage direct scans 0% 0% 0% Zone normal velocity 5105.086 6824.681 671.158 Zone dma32 velocity 112.473 794.858 745.896 Zone dma velocity 0.000 0.000 0.000 Page writes by reclaim 1929612.000 6861768.000 32821.000 Page writes file 1245752 6861750 32803 Page writes anon 683860 18 18 Page reclaim immediate 7484 40 239 Sector Reads 1130320 93996 86900 Sector Writes 13508052 10823500 11804436 Page rescued immediate 0 0 0 Slabs scanned 33536 27136 18560 Direct inode steals 0 0 0 Kswapd inode steals 8641 1035 0 Kswapd skipped wait 0 0 0 THP fault alloc 8 37 33 THP collapse alloc 508 552 515 THP splits 24 1 1 THP fault fallback 0 0 0 THP collapse fail 0 0 0 There are a number of observations to make here 1. Swap outs are almost eliminated. Swap ins are 0 indicating that the pages swapped were really unused anonymous pages. Related to that, major faults are much reduced. 2. kswapd efficiency was impacted by the initial series but with these follow-up patches, the efficiency is now at 66% indicating that far fewer pages were skipped during scanning due to dirty or writeback pages. 3. kswapd velocity is reduced indicating that fewer pages are being scanned with the follow-up series as kswapd now stalls when the tail of the LRU queue is full of unqueued dirty pages. The stall gives flushers a chance to catch-up so kswapd can reclaim clean pages when it wakes 4. In light of Zlatko's recent reports about zone scanning imbalances, mmtests now reports scanning velocity on a per-zone basis. With mainline, you can see that the scanning activity is dominated by the Normal zone with over 45 times more scanning in Normal than the DMA32 zone. With the series currently in mmotm, the ratio is slightly better but it is still the case that the bulk of scanning is in the highest zone. With this follow-up series, the ratio of scanning between the Normal and DMA32 zone is roughly equal. 5. As Dave Chinner observed, the current patches in mmotm increased the number of pages written from kswapd context which is expected to adversly impact IO performance. With the follow-up patches, far fewer pages are written from kswapd context than the mainline kernel 6. With the series in mmotm, fewer inodes were reclaimed by kswapd. With the follow-up series, there is less slab shrinking activity and no inodes were reclaimed. 7. Note that "Sectors Read" is drastically reduced implying that the source data being used for the IO is not being aggressively discarded due to page reclaim skipping over dirty pages and reclaiming clean pages. Note that the reducion in reads could also be due to inode data not being re-read from disk after a slab shrink. 3.9.0 3.9.0 3.9.0 vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10 Mean sda-avgqz 166.99 32.09 33.44 Mean sda-await 853.64 192.76 185.43 Mean sda-r_await 6.31 9.24 5.97 Mean sda-w_await 2992.81 202.65 192.43 Max sda-avgqz 1409.91 718.75 698.98 Max sda-await 6665.74 3538.00 3124.23 Max sda-r_await 58.96 111.95 58.00 Max sda-w_await 28458.94 3977.29 3148.61 In light of the changes in writes from reclaim context, the number of reads and Dave Chinner's concerns about IO performance I took a closer look at the IO stats for the test disk. Few observations 1. The average queue size is reduced by the initial series and roughly the same with this follow up. 2. Average wait times for writes are reduced and as the IO is completing faster it at least implies that the gain is because flushers are writing the files efficiently instead of page reclaim getting in the way. 3. The reduction in maximum write latency is staggering. 28 seconds down to 3 seconds. Jan Kara asked how NFS is affected by all of this. Unstable pages can be taken into account as one of the patches in the series shows but it is still the case that filesystems with unusual handling of dirty or writeback could still be treated better. Tests like postmark, fsmark and largedd showed up nothing useful. On my test setup, pages are simply not being written back from reclaim context with or without the patches and there are no changes in performance. My test setup probably is just not strong enough network-wise to be really interesting. I ran a longer-lived memcached test with IO going to NFS instead of a local disk parallelio 3.9.0 3.9.0 3.9.0 vanilla mm1-mmotm-20130522 mm1-lessdisrupt-v7r10 Ops memcachetest-0M 23323.00 ( 0.00%) 23241.00 ( -0.35%) 23321.00 ( -0.01%) Ops memcachetest-715M 25526.00 ( 0.00%) 24763.00 ( -2.99%) 23242.00 ( -8.95%) Ops memcachetest-2385M 8814.00 ( 0.00%) 26924.00 (205.47%) 23521.00 (166.86%) Ops memcachetest-4055M 5835.00 ( 0.00%) 26827.00 (359.76%) 25560.00 (338.05%) Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops io-duration-715M 65.00 ( 0.00%) 71.00 ( -9.23%) 11.00 ( 83.08%) Ops io-duration-2385M 129.00 ( 0.00%) 94.00 ( 27.13%) 53.00 ( 58.91%) Ops io-duration-4055M 301.00 ( 0.00%) 100.00 ( 66.78%) 108.00 ( 64.12%) Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-715M 14394.00 ( 0.00%) 949.00 ( 93.41%) 63.00 ( 99.56%) Ops swaptotal-2385M 401483.00 ( 0.00%) 24437.00 ( 93.91%) 30118.00 ( 92.50%) Ops swaptotal-4055M 554123.00 ( 0.00%) 35688.00 ( 93.56%) 63082.00 ( 88.62%) Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-715M 4522.00 ( 0.00%) 560.00 ( 87.62%) 63.00 ( 98.61%) Ops swapin-2385M 169861.00 ( 0.00%) 5026.00 ( 97.04%) 13917.00 ( 91.81%) Ops swapin-4055M 192374.00 ( 0.00%) 10056.00 ( 94.77%) 25729.00 ( 86.63%) Ops minorfaults-0M 1445969.00 ( 0.00%) 1520878.00 ( -5.18%) 1454024.00 ( -0.56%) Ops minorfaults-715M 1557288.00 ( 0.00%) 1528482.00 ( 1.85%) 1535776.00 ( 1.38%) Ops minorfaults-2385M 1692896.00 ( 0.00%) 1570523.00 ( 7.23%) 1559622.00 ( 7.87%) Ops minorfaults-4055M 1654985.00 ( 0.00%) 1581456.00 ( 4.44%) 1596713.00 ( 3.52%) Ops majorfaults-0M 0.00 ( 0.00%) 1.00 (-99.00%) 0.00 ( 0.00%) Ops majorfaults-715M 763.00 ( 0.00%) 265.00 ( 65.27%) 75.00 ( 90.17%) Ops majorfaults-2385M 23861.00 ( 0.00%) 894.00 ( 96.25%) 2189.00 ( 90.83%) Ops majorfaults-4055M 27210.00 ( 0.00%) 1569.00 ( 94.23%) 4088.00 ( 84.98%) 1. Performance does not collapse due to IO which is good. IO is also completing faster. Note with mmotm, IO completes in a third of the time and faster again with this series applied 2. Swapping is reduced, although not eliminated. The figures for the follow-up look bad but it does vary a bit as the stalling is not perfect for nfs or filesystems like ext3 with unusual handling of dirty and writeback pages 3. There are swapins, particularly with larger amounts of IO indicating that active pages are being reclaimed. However, the number of much reduced. 3.9.0 3.9.0 3.9.0 vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10 Minor Faults 36339175 35025445 35219699 Major Faults 310964 27108 51887 Swap Ins 2176399 173069 333316 Swap Outs 3344050 357228 504824 Direct pages scanned 8972 77283 43242 Kswapd pages scanned 20899983 8939566 14772851 Kswapd pages reclaimed 6193156 5172605 5231026 Direct pages reclaimed 8450 73802 39514 Kswapd efficiency 29% 57% 35% Kswapd velocity 3929.743 1847.499 3058.840 Direct efficiency 94% 95% 91% Direct velocity 1.687 15.972 8.954 Percentage direct scans 0% 0% 0% Zone normal velocity 3721.907 939.103 2185.142 Zone dma32 velocity 209.522 924.368 882.651 Zone dma velocity 0.000 0.000 0.000 Page writes by reclaim 4082185.000 526319.000 537114.000 Page writes file 738135 169091 32290 Page writes anon 3344050 357228 504824 Page reclaim immediate 9524 170 5595843 Sector Reads 8909900 861192 1483680 Sector Writes 13428980 1488744 2076800 Page rescued immediate 0 0 0 Slabs scanned 38016 31744 28672 Direct inode steals 0 0 0 Kswapd inode steals 424 0 0 Kswapd skipped wait 0 0 0 THP fault alloc 14 15 119 THP collapse alloc 1767 1569 1618 THP splits 30 29 25 THP fault fallback 0 0 0 THP collapse fail 8 5 0 Compaction stalls 17 41 100 Compaction success 7 31 95 Compaction failures 10 10 5 Page migrate success 7083 22157 62217 Page migrate failure 0 0 0 Compaction pages isolated 14847 48758 135830 Compaction migrate scanned 18328 48398 138929 Compaction free scanned 2000255 355827 1720269 Compaction cost 7 24 68 I guess the main takeaway again is the much reduced page writes from reclaim context and reduced reads. 3.9.0 3.9.0 3.9.0 vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10 Mean sda-avgqz 23.58 0.35 0.44 Mean sda-await 133.47 15.72 15.46 Mean sda-r_await 4.72 4.69 3.95 Mean sda-w_await 507.69 28.40 33.68 Max sda-avgqz 680.60 12.25 23.14 Max sda-await 3958.89 221.83 286.22 Max sda-r_await 63.86 61.23 67.29 Max sda-w_await 11710.38 883.57 1767.28 And as before, write wait times are much reduced. This patch: The patch "mm: vmscan: Have kswapd writeback pages based on dirty pages encountered, not priority" decides whether to writeback pages from reclaim context based on the number of dirty pages encountered. This situation is flagged too easily and flushers are not given the chance to catch up resulting in more pages being written from reclaim context and potentially impacting IO performance. The check for PageWriteback is also misplaced as it happens within a PageDirty check which is nonsense as the dirty may have been cleared for IO. The accounting is updated very late and pages that are already under writeback, were reactivated, could not unmapped or could not be released are all missed. Similarly, a page is considered congested for reasons other than being congested and pages that cannot be written out in the correct context are skipped. Finally, it considers stalling and writing back filesystem pages due to encountering dirty anonymous pages at the tail of the LRU which is dumb. This patch causes kswapd to begin writing filesystem pages from reclaim context only if page reclaim found that all filesystem pages at the tail of the LRU were unqueued dirty pages. Before it starts writing filesystem pages, it will stall to give flushers a chance to catch up. The decision on whether wait_iff_congested is also now determined by dirty filesystem pages only. Congested pages are based on whether the underlying BDI is congested regardless of the context of the reclaiming process. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7c954f6d |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: move logic from balance_pgdat() to kswapd_shrink_zone() balance_pgdat() is very long and some of the logic can and should be internal to kswapd_shrink_zone(). Move it so the flow of balance_pgdat() is marginally easier to follow. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b7ea3c41 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: check if kswapd should writepage once per pgdat scan Currently kswapd checks if it should start writepage as it shrinks each zone without taking into consideration if the zone is balanced or not. This is not wrong as such but it does not make much sense either. This patch checks once per pgdat scan if kswapd should be writing pages. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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283aba9f |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: block kswapd if it is encountering pages under writeback Historically, kswapd used to congestion_wait() at higher priorities if it was not making forward progress. This made no sense as the failure to make progress could be completely independent of IO. It was later replaced by wait_iff_congested() and removed entirely by commit 258401a6 (mm: don't wait on congested zones in balance_pgdat()) as it was duplicating logic in shrink_inactive_list(). This is problematic. If kswapd encounters many pages under writeback and it continues to scan until it reaches the high watermark then it will quickly skip over the pages under writeback and reclaim clean young pages or push applications out to swap. The use of wait_iff_congested() is not suited to kswapd as it will only stall if the underlying BDI is really congested or a direct reclaimer was unable to write to the underlying BDI. kswapd bypasses the BDI congestion as it sets PF_SWAPWRITE but even if this was taken into account then it would cause direct reclaimers to stall on writeback which is not desirable. This patch sets a ZONE_WRITEBACK flag if direct reclaim or kswapd is encountering too many pages under writeback. If this flag is set and kswapd encounters a PageReclaim page under writeback then it'll assume that the LRU lists are being recycled too quickly before IO can complete and block waiting for some IO to complete. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d43006d5 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: have kswapd writeback pages based on dirty pages encountered, not priority Currently kswapd queues dirty pages for writeback if scanning at an elevated priority but the priority kswapd scans at is not related to the number of unqueued dirty encountered. Since commit "mm: vmscan: Flatten kswapd priority loop", the priority is related to the size of the LRU and the zone watermark which is no indication as to whether kswapd should write pages or not. This patch tracks if an excessive number of unqueued dirty pages are being encountered at the end of the LRU. If so, it indicates that dirty pages are being recycled before flusher threads can clean them and flags the zone so that kswapd will start writing pages until the zone is balanced. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9aa41348 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not allow kswapd to scan at maximum priority Page reclaim at priority 0 will scan the entire LRU as priority 0 is considered to be a near OOM condition. Kswapd can reach priority 0 quite easily if it is encountering a large number of pages it cannot reclaim such as pages under writeback. When this happens, kswapd reclaims very aggressively even though there may be no real risk of allocation failure or OOM. This patch prevents kswapd reaching priority 0 and trying to reclaim the world. Direct reclaimers will still reach priority 0 in the event of an OOM situation. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2ab44f43 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: decide whether to compact the pgdat based on reclaim progress In the past, kswapd makes a decision on whether to compact memory after the pgdat was considered balanced. This more or less worked but it is late to make such a decision and does not fit well now that kswapd makes a decision whether to exit the zone scanning loop depending on reclaim progress. This patch will compact a pgdat if at least the requested number of pages were reclaimed from unbalanced zones for a given priority. If any zone is currently balanced, kswapd will not call compaction as it is expected the necessary pages are already available. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b8e83b94 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: flatten kswapd priority loop kswapd stops raising the scanning priority when at least SWAP_CLUSTER_MAX pages have been reclaimed or the pgdat is considered balanced. It then rechecks if it needs to restart at DEF_PRIORITY and whether high-order reclaim needs to be reset. This is not wrong per-se but it is confusing to follow and forcing kswapd to stay at DEF_PRIORITY may require several restarts before it has scanned enough pages to meet the high watermark even at 100% efficiency. This patch irons out the logic a bit by controlling when priority is raised and removing the "goto loop_again". This patch has kswapd raise the scanning priority until it is scanning enough pages that it could meet the high watermark in one shrink of the LRU lists if it is able to reclaim at 100% efficiency. It will not raise the scanning prioirty higher unless it is failing to reclaim any pages. To avoid infinite looping for high-order allocation requests kswapd will not reclaim for high-order allocations when it has reclaimed at least twice the number of pages as the allocation request. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e82e0561 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: obey proportional scanning requirements for kswapd Simplistically, the anon and file LRU lists are scanned proportionally depending on the value of vm.swappiness although there are other factors taken into account by get_scan_count(). The patch "mm: vmscan: Limit the number of pages kswapd reclaims" limits the number of pages kswapd reclaims but it breaks this proportional scanning and may evenly shrink anon/file LRUs regardless of vm.swappiness. This patch preserves the proportional scanning and reclaim. It does mean that kswapd will reclaim more than requested but the number of pages will be related to the high watermark. [mhocko@suse.cz: Correct proportional reclaim for memcg and simplify] [kamezawa.hiroyu@jp.fujitsu.com: Recalculate scan based on target] [hannes@cmpxchg.org: Account for already scanned pages properly] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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75485363 |
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03-Jul-2013 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: limit the number of pages kswapd reclaims at each priority This series does not fix all the current known problems with reclaim but it addresses one important swapping bug when there is background IO. Changelog since V3 - Drop the slab shrink changes in light of Glaubers series and discussions highlighted that there were a number of potential problems with the patch. (mel) - Rebased to 3.10-rc1 Changelog since V2 - Preserve ratio properly for proportional scanning (kamezawa) Changelog since V1 - Rename ZONE_DIRTY to ZONE_TAIL_LRU_DIRTY (andi) - Reformat comment in shrink_page_list (andi) - Clarify some comments (dhillf) - Rework how the proportional scanning is preserved - Add PageReclaim check before kswapd starts writeback - Reset sc.nr_reclaimed on every full zone scan Kswapd and page reclaim behaviour has been screwy in one way or the other for a long time. Very broadly speaking it worked in the far past because machines were limited in memory so it did not have that many pages to scan and it stalled congestion_wait() frequently to prevent it going completely nuts. In recent times it has behaved very unsatisfactorily with some of the problems compounded by the removal of stall logic and the introduction of transparent hugepage support with high-order reclaims. There are many variations of bugs that are rooted in this area. One example is reports of a large copy operations or backup causing the machine to grind to a halt or applications pushed to swap. Sometimes in low memory situations a large percentage of memory suddenly gets reclaimed. In other cases an application starts and kswapd hits 100% CPU usage for prolonged periods of time and so on. There is now talk of introducing features like an extra free kbytes tunable to work around aspects of the problem instead of trying to deal with it. It's compounded by the problem that it can be very workload and machine specific. This series aims at addressing some of the worst of these problems without attempting to fundmentally alter how page reclaim works. Patches 1-2 limits the number of pages kswapd reclaims while still obeying the anon/file proportion of the LRUs it should be scanning. Patches 3-4 control how and when kswapd raises its scanning priority and deletes the scanning restart logic which is tricky to follow. Patch 5 notes that it is too easy for kswapd to reach priority 0 when scanning and then reclaim the world. Down with that sort of thing. Patch 6 notes that kswapd starts writeback based on scanning priority which is not necessarily related to dirty pages. It will have kswapd writeback pages if a number of unqueued dirty pages have been recently encountered at the tail of the LRU. Patch 7 notes that sometimes kswapd should stall waiting on IO to complete to reduce LRU churn and the likelihood that it'll reclaim young clean pages or push applications to swap. It will cause kswapd to block on IO if it detects that pages being reclaimed under writeback are recycling through the LRU before the IO completes. Patchies 8-9 are cosmetic but balance_pgdat() is easier to follow after they are applied. This was tested using memcached+memcachetest while some background IO was in progress as implemented by the parallel IO tests implement in MM Tests. memcachetest benchmarks how many operations/second memcached can service and it is run multiple times. It starts with no background IO and then re-runs the test with larger amounts of IO in the background to roughly simulate a large copy in progress. The expectation is that the IO should have little or no impact on memcachetest which is running entirely in memory. 3.10.0-rc1 3.10.0-rc1 vanilla lessdisrupt-v4 Ops memcachetest-0M 22155.00 ( 0.00%) 22180.00 ( 0.11%) Ops memcachetest-715M 22720.00 ( 0.00%) 22355.00 ( -1.61%) Ops memcachetest-2385M 3939.00 ( 0.00%) 23450.00 (495.33%) Ops memcachetest-4055M 3628.00 ( 0.00%) 24341.00 (570.92%) Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops io-duration-715M 12.00 ( 0.00%) 7.00 ( 41.67%) Ops io-duration-2385M 118.00 ( 0.00%) 21.00 ( 82.20%) Ops io-duration-4055M 162.00 ( 0.00%) 36.00 ( 77.78%) Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-715M 140134.00 ( 0.00%) 18.00 ( 99.99%) Ops swaptotal-2385M 392438.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-4055M 449037.00 ( 0.00%) 27864.00 ( 93.79%) Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-715M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-2385M 148031.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-4055M 135109.00 ( 0.00%) 0.00 ( 0.00%) Ops minorfaults-0M 1529984.00 ( 0.00%) 1530235.00 ( -0.02%) Ops minorfaults-715M 1794168.00 ( 0.00%) 1613750.00 ( 10.06%) Ops minorfaults-2385M 1739813.00 ( 0.00%) 1609396.00 ( 7.50%) Ops minorfaults-4055M 1754460.00 ( 0.00%) 1614810.00 ( 7.96%) Ops majorfaults-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops majorfaults-715M 185.00 ( 0.00%) 180.00 ( 2.70%) Ops majorfaults-2385M 24472.00 ( 0.00%) 101.00 ( 99.59%) Ops majorfaults-4055M 22302.00 ( 0.00%) 229.00 ( 98.97%) Note how the vanilla kernels performance collapses when there is enough IO taking place in the background. This drop in performance is part of what users complain of when they start backups. Note how the swapin and major fault figures indicate that processes were being pushed to swap prematurely. With the series applied, there is no noticable performance drop and while there is still some swap activity, it's tiny. 20 iterations of this test were run in total and averaged. Every 5 iterations, additional IO was generated in the background using dd to measure how the workload was impacted. The 0M, 715M, 2385M and 4055M subblock refer to the amount of IO going on in the background at each iteration. So memcachetest-2385M is reporting how many transactions/second memcachetest recorded on average over 5 iterations while there was 2385M of IO going on in the ground. There are six blocks of information reported here memcachetest is the transactions/second reported by memcachetest. In the vanilla kernel note that performance drops from around 22K/sec to just under 4K/second when there is 2385M of IO going on in the background. This is one type of performance collapse users complain about if a large cp or backup starts in the background io-duration refers to how long it takes for the background IO to complete. It's showing that with the patched kernel that the IO completes faster while not interfering with the memcache workload swaptotal is the total amount of swap traffic. With the patched kernel, the total amount of swapping is much reduced although it is still not zero. swapin in this case is an indication as to whether we are swap trashing. The closer the swapin/swapout ratio is to 1, the worse the trashing is. Note with the patched kernel that there is no swapin activity indicating that all the pages swapped were really inactive unused pages. minorfaults are just minor faults. An increased number of minor faults can indicate that page reclaim is unmapping the pages but not swapping them out before they are faulted back in. With the patched kernel, there is only a small change in minor faults majorfaults are just major faults in the target workload and a high number can indicate that a workload is being prematurely swapped. With the patched kernel, major faults are much reduced. As there are no swapin's recorded so it's not being swapped. The likely explanation is that that libraries or configuration files used by the workload during startup get paged out by the background IO. Overall with the series applied, there is no noticable performance drop due to background IO and while there is still some swap activity, it's tiny and the lack of swapins imply that the swapped pages were inactive and unused. 3.10.0-rc1 3.10.0-rc1 vanilla lessdisrupt-v4 Page Ins 1234608 101892 Page Outs 12446272 11810468 Swap Ins 283406 0 Swap Outs 698469 27882 Direct pages scanned 0 136480 Kswapd pages scanned 6266537 5369364 Kswapd pages reclaimed 1088989 930832 Direct pages reclaimed 0 120901 Kswapd efficiency 17% 17% Kswapd velocity 5398.371 4635.115 Direct efficiency 100% 88% Direct velocity 0.000 117.817 Percentage direct scans 0% 2% Page writes by reclaim 1655843 4009929 Page writes file 957374 3982047 Page writes anon 698469 27882 Page reclaim immediate 5245 1745 Page rescued immediate 0 0 Slabs scanned 33664 25216 Direct inode steals 0 0 Kswapd inode steals 19409 778 Kswapd skipped wait 0 0 THP fault alloc 35 30 THP collapse alloc 472 401 THP splits 27 22 THP fault fallback 0 0 THP collapse fail 0 1 Compaction stalls 0 4 Compaction success 0 0 Compaction failures 0 4 Page migrate success 0 0 Page migrate failure 0 0 Compaction pages isolated 0 0 Compaction migrate scanned 0 0 Compaction free scanned 0 0 Compaction cost 0 0 NUMA PTE updates 0 0 NUMA hint faults 0 0 NUMA hint local faults 0 0 NUMA pages migrated 0 0 AutoNUMA cost 0 0 Unfortunately, note that there is a small amount of direct reclaim due to kswapd no longer reclaiming the world. ftrace indicates that the direct reclaim stalls are mostly harmless with the vast bulk of the stalls incurred by dd 23 tclsh-3367 38 memcachetest-13733 49 memcachetest-12443 57 tee-3368 1541 dd-13826 1981 dd-12539 A consequence of the direct reclaim for dd is that the processes for the IO workload may show a higher system CPU usage. There is also a risk that kswapd not reclaiming the world may mean that it stays awake balancing zones, does not stall on the appropriate events and continually scans pages it cannot reclaim consuming CPU. This will be visible as continued high CPU usage but in my own tests I only saw a single spike lasting less than a second and I did not observe any problems related to reclaim while running the series on my desktop. This patch: The number of pages kswapd can reclaim is bound by the number of pages it scans which is related to the size of the zone and the scanning priority. In many cases the priority remains low because it's reset every SWAP_CLUSTER_MAX reclaimed pages but in the event kswapd scans a large number of pages it cannot reclaim, it will raise the priority and potentially discard a large percentage of the zone as sc->nr_to_reclaim is ULONG_MAX. The user-visible effect is a reclaim "spike" where a large percentage of memory is suddenly freed. It would be bad enough if this was just unused memory but because of how anon/file pages are balanced it is possible that applications get pushed to swap unnecessarily. This patch limits the number of pages kswapd will reclaim to the high watermark. Reclaim will still overshoot due to it not being a hard limit as shrink_lruvec() will ignore the sc.nr_to_reclaim at DEF_PRIORITY but it prevents kswapd reclaiming the world at higher priorities. The number of pages it reclaims is not adjusted for high-order allocations as kswapd will reclaim excessively if it is to balance zones for high-order allocations. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5bc7b8ac |
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29-Apr-2013 |
Shaohua Li <shli@kernel.org> |
mm: thp: add split tail pages to shrink page list in page reclaim In page reclaim, huge page is split. split_huge_page() adds tail pages to LRU list. Since we are reclaiming a huge page, it's better we reclaim all subpages of the huge page instead of just the head page. This patch adds split tail pages to shrink page list so the tail pages can be reclaimed soon. Before this patch, run a swap workload: thp_fault_alloc 3492 thp_fault_fallback 608 thp_collapse_alloc 6 thp_collapse_alloc_failed 0 thp_split 916 With this patch: thp_fault_alloc 4085 thp_fault_fallback 16 thp_collapse_alloc 90 thp_collapse_alloc_failed 0 thp_split 1272 fallback allocation is reduced a lot. [akpm@linux-foundation.org: fix CONFIG_SWAP=n build] Signed-off-by: Shaohua Li <shli@fusionio.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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70ddf637 |
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29-Apr-2013 |
Anton Vorontsov <anton.vorontsov@linaro.org> |
memcg: add memory.pressure_level events With this patch userland applications that want to maintain the interactivity/memory allocation cost can use the pressure level notifications. The levels are defined like this: The "low" level means that the system is reclaiming memory for new allocations. Monitoring this reclaiming activity might be useful for maintaining cache level. Upon notification, the program (typically "Activity Manager") might analyze vmstat and act in advance (i.e. prematurely shutdown unimportant services). The "medium" level means that the system is experiencing medium memory pressure, the system might be making swap, paging out active file caches, etc. Upon this event applications may decide to further analyze vmstat/zoneinfo/memcg or internal memory usage statistics and free any resources that can be easily reconstructed or re-read from a disk. The "critical" level means that the system is actively thrashing, it is about to out of memory (OOM) or even the in-kernel OOM killer is on its way to trigger. Applications should do whatever they can to help the system. It might be too late to consult with vmstat or any other statistics, so it's advisable to take an immediate action. The events are propagated upward until the event is handled, i.e. the events are not pass-through. Here is what this means: for example you have three cgroups: A->B->C. Now you set up an event listener on cgroups A, B and C, and suppose group C experiences some pressure. In this situation, only group C will receive the notification, i.e. groups A and B will not receive it. This is done to avoid excessive "broadcasting" of messages, which disturbs the system and which is especially bad if we are low on memory or thrashing. So, organize the cgroups wisely, or propagate the events manually (or, ask us to implement the pass-through events, explaining why would you need them.) Performance wise, the memory pressure notifications feature itself is lightweight and does not require much of bookkeeping, in contrast to the rest of memcg features. Unfortunately, as of current memcg implementation, pages accounting is an inseparable part and cannot be turned off. The good news is that there are some efforts[1] to improve the situation; plus, implementing the same, fully API-compatible[2] interface for CONFIG_MEMCG=n case (e.g. embedded) is also a viable option, so it will not require any changes on the userland side. [1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291 [2] http://lkml.org/lkml/2013/2/21/454 [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings] Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Leonid Moiseichuk <leonid.moiseichuk@nokia.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2d42a40d |
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29-Apr-2013 |
Hillf Danton <dhillf@gmail.com> |
mm/vmscan.c: minor cleanup for kswapd Local variable total_scanned is no longer used. Signed-off-by: Hillf Danton <dhillf@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d72515b8 |
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17-Apr-2013 |
Xishi Qiu <qiuxishi@huawei.com> |
mm/vmscan: fix error return in kswapd_run() Fix the error return value in kswapd_run(). The bug was introduced by commit d5dc0ad928fb ("mm/vmscan: fix error number for failed kthread"). Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reported-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b21e0b90 |
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22-Feb-2013 |
Zhang Yanfei <zhangyanfei@cn.fujitsu.com> |
vmscan: change type of vm_total_pages to unsigned long This variable is calculated from nr_free_pagecache_pages so change its type to unsigned long. Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0e50ce3b |
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22-Feb-2013 |
Minchan Kim <minchan@kernel.org> |
mm: use up free swap space before reaching OOM kill Recently, Luigi reported there are lots of free swap space when OOM happens. It's easily reproduced on zram-over-swap, where many instance of memory hogs are running and laptop_mode is enabled. He said there was no problem when he disabled laptop_mode. The problem when I investigate problem is following as. Assumption for easy explanation: There are no page cache page in system because they all are already reclaimed. 1. try_to_free_pages disable may_writepage when laptop_mode is enabled. 2. shrink_inactive_list isolates victim pages from inactive anon lru list. 3. shrink_page_list adds them to swapcache via add_to_swap but it doesn't pageout because sc->may_writepage is 0 so the page is rotated back into inactive anon lru list. The add_to_swap made the page Dirty by SetPageDirty. 4. 3 couldn't reclaim any pages so do_try_to_free_pages increase priority and retry reclaim with higher priority. 5. shrink_inactlive_list try to isolate victim pages from inactive anon lru list but got failed because it try to isolate pages with ISOLATE_CLEAN mode but inactive anon lru list is full of dirty pages by 3 so it just returns without any reclaim progress. 6. do_try_to_free_pages doesn't set may_writepage due to zero total_scanned. Because sc->nr_scanned is increased by shrink_page_list but we don't call shrink_page_list in 5 due to short of isolated pages. Above loop is continued until OOM happens. The problem didn't happen before [1] was merged because old logic's isolatation in shrink_inactive_list was successful and tried to call shrink_page_list to pageout them but it still ends up failed to page out by may_writepage. But important point is that sc->nr_scanned was increased although we couldn't swap out them so do_try_to_free_pages could set may_writepages. Since commit f80c0673610e ("mm: zone_reclaim: make isolate_lru_page() filter-aware") was introduced, it's not a good idea any more to depends on only the number of scanned pages for setting may_writepage. So this patch adds new trigger point of setting may_writepage as below DEF_PRIOIRTY - 2 which is used to show the significant memory pressure in VM so it's good fit for our purpose which would be better to lose power saving or clickety rather than OOM killing. Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Luigi Semenzato <semenzato@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e3790144 |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: refactor inactive_file_is_low() to use get_lru_size() An inactive file list is considered low when its active counterpart is bigger, regardless of whether it is a global zone LRU list or a memcg zone LRU list. The only difference is in how the LRU size is assessed. get_lru_size() does the right thing for both global and memcg reclaim situations. Get rid of inactive_file_is_low_global() and mem_cgroup_inactive_file_is_low() by using get_lru_size() and compare the numbers in common code. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ec8acf20 |
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22-Feb-2013 |
Shaohua Li <shli@kernel.org> |
swap: add per-partition lock for swapfile swap_lock is heavily contended when I test swap to 3 fast SSD (even slightly slower than swap to 2 such SSD). The main contention comes from swap_info_get(). This patch tries to fix the gap with adding a new per-partition lock. Global data like nr_swapfiles, total_swap_pages, least_priority and swap_list are still protected by swap_lock. nr_swap_pages is an atomic now, it can be changed without swap_lock. In theory, it's possible get_swap_page() finds no swap pages but actually there are free swap pages. But sounds not a big problem. Accessing partition specific data (like scan_swap_map and so on) is only protected by swap_info_struct.lock. Changing swap_info_struct.flags need hold swap_lock and swap_info_struct.lock, because scan_scan_map() will check it. read the flags is ok with either the locks hold. If both swap_lock and swap_info_struct.lock must be hold, we always hold the former first to avoid deadlock. swap_entry_free() can change swap_list. To delete that code, we add a new highest_priority_index. Whenever get_swap_page() is called, we check it. If it's valid, we use it. It's a pity get_swap_page() still holds swap_lock(). But in practice, swap_lock() isn't heavily contended in my test with this patch (or I can say there are other much more heavier bottlenecks like TLB flush). And BTW, looks get_swap_page() doesn't really need the lock. We never free swap_info[] and we check SWAP_WRITEOK flag. The only risk without the lock is we could swapout to some low priority swap, but we can quickly recover after several rounds of swap, so sounds not a big deal to me. But I'd prefer to fix this if it's a real problem. "swap: make each swap partition have one address_space" improved the swapout speed from 1.7G/s to 2G/s. This patch further improves the speed to 2.3G/s, so around 15% improvement. It's a multi-process test, so TLB flush isn't the biggest bottleneck before the patches. [arnd@arndb.de: fix it for nommu] [hughd@google.com: add missing unlock] [minchan@kernel.org: get rid of lockdep whinge on sys_swapon] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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21caf2fc |
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22-Feb-2013 |
Ming Lei <ming.lei@canonical.com> |
mm: teach mm by current context info to not do I/O during memory allocation This patch introduces PF_MEMALLOC_NOIO on process flag('flags' field of 'struct task_struct'), so that the flag can be set by one task to avoid doing I/O inside memory allocation in the task's context. The patch trys to solve one deadlock problem caused by block device, and the problem may happen at least in the below situations: - during block device runtime resume, if memory allocation with GFP_KERNEL is called inside runtime resume callback of any one of its ancestors(or the block device itself), the deadlock may be triggered inside the memory allocation since it might not complete until the block device becomes active and the involed page I/O finishes. The situation is pointed out first by Alan Stern. It is not a good approach to convert all GFP_KERNEL[1] in the path into GFP_NOIO because several subsystems may be involved(for example, PCI, USB and SCSI may be involved for usb mass stoarage device, network devices involved too in the iSCSI case) - during block device runtime suspend, because runtime resume need to wait for completion of concurrent runtime suspend. - during error handling of usb mass storage deivce, USB bus reset will be put on the device, so there shouldn't have any memory allocation with GFP_KERNEL during USB bus reset, otherwise the deadlock similar with above may be triggered. Unfortunately, any usb device may include one mass storage interface in theory, so it requires all usb interface drivers to handle the situation. In fact, most usb drivers don't know how to handle bus reset on the device and don't provide .pre_set() and .post_reset() callback at all, so USB core has to unbind and bind driver for these devices. So it is still not practical to resort to GFP_NOIO for solving the problem. Also the introduced solution can be used by block subsystem or block drivers too, for example, set the PF_MEMALLOC_NOIO flag before doing actual I/O transfer. It is not a good idea to convert all these GFP_KERNEL in the affected path into GFP_NOIO because these functions doing that may be implemented as library and will be called in many other contexts. In fact, memalloc_noio_flags() can convert some of current static GFP_NOIO allocation into GFP_KERNEL back in other non-affected contexts, at least almost all GFP_NOIO in USB subsystem can be converted into GFP_KERNEL after applying the approach and make allocation with GFP_NOIO only happen in runtime resume/bus reset/block I/O transfer contexts generally. [1], several GFP_KERNEL allocation examples in runtime resume path - pci subsystem acpi_os_allocate <-acpi_ut_allocate <-ACPI_ALLOCATE_ZEROED <-acpi_evaluate_object <-__acpi_bus_set_power <-acpi_bus_set_power <-acpi_pci_set_power_state <-platform_pci_set_power_state <-pci_platform_power_transition <-__pci_complete_power_transition <-pci_set_power_state <-pci_restore_standard_config <-pci_pm_runtime_resume - usb subsystem usb_get_status <-finish_port_resume <-usb_port_resume <-generic_resume <-usb_resume_device <-usb_resume_both <-usb_runtime_resume - some individual usb drivers usblp, uvc, gspca, most of dvb-usb-v2 media drivers, cpia2, az6007, .... That is just what I have found. Unfortunately, this allocation can only be found by human being now, and there should be many not found since any function in the resume path(call tree) may allocate memory with GFP_KERNEL. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Oliver Neukum <oneukum@suse.de> Cc: Jiri Kosina <jiri.kosina@suse.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: David Decotigny <david.decotigny@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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258401a6 |
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22-Feb-2013 |
Zlatko Calusic <zlatko.calusic@iskon.hr> |
mm: don't wait on congested zones in balance_pgdat() From: Zlatko Calusic <zlatko.calusic@iskon.hr> Commit 92df3a723f84 ("mm: vmscan: throttle reclaim if encountering too many dirty pages under writeback") introduced waiting on congested zones based on a sane algorithm in shrink_inactive_list(). What this means is that there's no more need for throttling and additional heuristics in balance_pgdat(). So, let's remove it and tidy up the code. Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b40da049 |
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22-Feb-2013 |
Jiang Liu <liuj97@gmail.com> |
mm: use zone->present_pages instead of zone->managed_pages where appropriate Now we have zone->managed_pages for "pages managed by the buddy system in the zone", so replace zone->present_pages with zone->managed_pages if what the user really wants is number of allocatable pages. Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Maciej Rutecki <maciej.rutecki@gmail.com> Cc: Chris Clayton <chris2553@googlemail.com> Cc: "Rafael J . Wysocki" <rjw@sisk.pl> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jianguo Wu <wujianguo@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
dafcb73e |
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22-Feb-2013 |
Zlatko Calusic <zlatko.calusic@iskon.hr> |
mm: avoid calling pgdat_balanced() needlessly Now that balance_pgdat() is slightly tidied up, thanks to more capable pgdat_balanced(), it's become obvious that pgdat_balanced() is called to check the status, then break the loop if pgdat is balanced, just to be immediately called again. The second call is completely unnecessary, of course. The patch introduces pgdat_is_balanced boolean, which helps resolve the above suboptimal behavior, with the added benefit of slightly better documenting one other place in the function where we jump and skip lots of code. Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a394cb8e |
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22-Feb-2013 |
Michal Hocko <mhocko@suse.cz> |
memcg,vmscan: do not break out targeted reclaim without reclaimed pages Targeted (hard resp soft) reclaim has traditionally tried to scan one group with decreasing priority until nr_to_reclaim (SWAP_CLUSTER_MAX pages) is reclaimed or all priorities are exhausted. The reclaim is then retried until the limit is met. This approach, however, doesn't work well with deeper hierarchies where groups higher in the hierarchy do not have any or only very few pages (this usually happens if those groups do not have any tasks and they have only re-parented pages after some of their children is removed). Those groups are reclaimed with decreasing priority pointlessly as there is nothing to reclaim from them. An easiest fix is to break out of the memcg iteration loop in shrink_zone only if the whole hierarchy has been visited or sufficient pages have been reclaimed. This is also more natural because the reclaimer expects that the hierarchy under the given root is reclaimed. As a result we can simplify the soft limit reclaim which does its own iteration. [yinghan@google.com: break out of the hierarchy loop only if nr_reclaimed exceeded nr_to_reclaim] [akpm@linux-foundation.org: use conventional comparison order] Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Ying Han <yinghan@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
62b726c1 |
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22-Feb-2013 |
Andrew Morton <akpm@linux-foundation.org> |
mm/vmscan.c:__zone_reclaim(): replace max_t() with max() "mm: vmscan: save work scanning (almost) empty LRU lists" made SWAP_CLUSTER_MAX an unsigned long. Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9b4f98cd |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: compaction works against zones, not lruvecs The restart logic for when reclaim operates back to back with compaction is currently applied on the lruvec level. But this does not make sense, because the container of interest for compaction is a zone as a whole, not the zone pages that are part of a certain memory cgroup. Negative impact is bounded. For one, the code checks that the lruvec has enough reclaim candidates, so it does not risk getting stuck on a condition that can not be fulfilled. And the unfairness of hammering on one particular memory cgroup to make progress in a zone will be amortized by the round robin manner in which reclaim goes through the memory cgroups. Still, this can lead to unnecessary allocation latencies when the code elects to restart on a hard to reclaim or small group when there are other, more reclaimable groups in the zone. Move this logic to the zone level and restart reclaim for all memory cgroups in a zone when compaction requires more free pages from it. [akpm@linux-foundation.org: no need for min_t] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9a265114 |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: clean up get_scan_count() Reclaim pressure balance between anon and file pages is calculated through a tuple of numerators and a shared denominator. Exceptional cases that want to force-scan anon or file pages configure the numerators and denominator such that one list is preferred, which is not necessarily the most obvious way: fraction[0] = 1; fraction[1] = 0; denominator = 1; goto out; Make this easier by making the force-scan cases explicit and use the fractionals only in case they are calculated from reclaim history. [akpm@linux-foundation.org: avoid using unintialized_var()] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
11d16c25 |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: improve comment on low-page cache handling Fix comment style and elaborate on why anonymous memory is force-scanned when file cache runs low. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
10316b31 |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: clarify how swappiness, highest priority, memcg interact A swappiness of 0 has a slightly different meaning for global reclaim (may swap if file cache really low) and memory cgroup reclaim (never swap, ever). In addition, global reclaim at highest priority will scan all LRU lists equal to their size and ignore other balancing heuristics. UNLESS swappiness forbids swapping, then the lists are balanced based on recent reclaim effectiveness. UNLESS file cache is running low, then anonymous pages are force-scanned. This (total mess of a) behaviour is implicit and not obvious from the way the code is organized. At least make it apparent in the code flow and document the conditions. It will be it easier to come up with sane semantics later. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Satoru Moriya <satoru.moriya@hds.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d778df51 |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: save work scanning (almost) empty LRU lists In certain cases (kswapd reclaim, memcg target reclaim), a fixed minimum amount of pages is scanned from the LRU lists on each iteration, to make progress. Do not make this minimum bigger than the respective LRU list size, however, and save some busy work trying to isolate and reclaim pages that are not there. Empty LRU lists are quite common with memory cgroups in NUMA environments because there exists a set of LRU lists for each zone for each memory cgroup, while the memory of a single cgroup is expected to stay on just one node. The number of expected empty LRU lists is thus memcgs * (nodes - 1) * lru types Each attempt to reclaim from an empty LRU list does expensive size comparisons between lists, acquires the zone's lru lock etc. Avoid that. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
7c5bd705 |
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22-Feb-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcg: only evict file pages when we have plenty Commit e9868505987a ("mm, vmscan: only evict file pages when we have plenty") makes a point of not going for anonymous memory while there is still enough inactive cache around. The check was added only for global reclaim, but it is just as useful to reduce swapping in memory cgroup reclaim: 200M-memcg-defconfig-j2 vanilla patched Real time 454.06 ( +0.00%) 453.71 ( -0.08%) User time 668.57 ( +0.00%) 668.73 ( +0.02%) System time 128.92 ( +0.00%) 129.53 ( +0.46%) Swap in 1246.80 ( +0.00%) 814.40 ( -34.65%) Swap out 1198.90 ( +0.00%) 827.00 ( -30.99%) Pages allocated 16431288.10 ( +0.00%) 16434035.30 ( +0.02%) Major faults 681.50 ( +0.00%) 593.70 ( -12.86%) THP faults 237.20 ( +0.00%) 242.40 ( +2.18%) THP collapse 241.20 ( +0.00%) 248.50 ( +3.01%) THP splits 157.30 ( +0.00%) 161.40 ( +2.59%) Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
fcb35a9b |
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21-Dec-2012 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
MM: vmscan: remove __devinit attribute. CONFIG_HOTPLUG is going away as an option. As a result, the __dev* markings need to be removed. This change removes the use of __devinit from the file. Based on patches originally written by Bill Pemberton, but redone by me in order to handle some of the coding style issues better, by hand. Cc: Bill Pemberton <wfp5p@virginia.edu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
ecccd124 |
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27-Dec-2012 |
Zlatko Calusic <zlatko.calusic@iskon.hr> |
mm: fix null pointer dereference in wait_iff_congested() An unintended consequence of commit 4ae0a48b5efc ("mm: modify pgdat_balanced() so that it also handles order-0") is that wait_iff_congested() can now be called with NULL 'struct zone *' producing kernel oops like this: BUG: unable to handle kernel NULL pointer dereference IP: [<ffffffff811542d9>] wait_iff_congested+0x59/0x140 This trivial patch fixes it. Reported-by: Zhouping Liu <zliu@redhat.com> Reported-and-tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
4ae0a48b |
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23-Dec-2012 |
Zlatko Calusic <zlatko.calusic@iskon.hr> |
mm: modify pgdat_balanced() so that it also handles order-0 Teach pgdat_balanced() about order-0 allocations so that we can simplify code in a few places in vmstat.c. Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
cda73a10 |
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19-Dec-2012 |
Zlatko Calusic <zlatko.calusic@iskon.hr> |
mm: do not sleep in balance_pgdat if there's no i/o congestion On a 4GB RAM machine, where Normal zone is much smaller than DMA32 zone, the Normal zone gets fragmented in time. This requires relatively more pressure in balance_pgdat to get the zone above the required watermark. Unfortunately, the congestion_wait() call in there slows it down for a completely wrong reason, expecting that there's a lot of writeback/swapout, even when there's none (much more common). After a few days, when fragmentation progresses, this flawed logic translates to a very high CPU iowait times, even though there's no I/O congestion at all. If THP is enabled, the problem occurs sooner, but I was able to see it even on !THP kernels, just by giving it a bit more time to occur. The proper way to deal with this is to not wait, unless there's congestion. Thanks to Mel Gorman, we already have the function that perfectly fits the job. The patch was tested on a machine which nicely revealed the problem after only 1 day of uptime, and it's been working great. Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3cf23841 |
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18-Dec-2012 |
Fengguang Wu <fengguang.wu@intel.com> |
mm/vmscan.c: avoid possible deadlock caused by too_many_isolated() Neil found that if too_many_isolated() returns true while performing direct reclaim we can end up waiting for other threads to complete their direct reclaim. If those threads are allowed to enter the FS or IO to free memory, but this thread is not, then it is possible that those threads will be waiting on this thread and so we get a circular deadlock. some task enters direct reclaim with GFP_KERNEL => too_many_isolated() false => vmscan and run into dirty pages => pageout() => take some FS lock => fs/block code does GFP_NOIO allocation => enter direct reclaim again => too_many_isolated() true => waiting for others to progress, however the other tasks may be circular waiting for the FS lock.. The fix is to let !__GFP_IO and !__GFP_FS direct reclaims enjoy higher priority than normal ones, by lowering the throttle threshold for the latter. Allowing ~1/8 isolated pages in normal is large enough. For example, for a 1GB LRU list, that's ~128MB isolated pages, or 1k blocked tasks (each isolates 32 4KB pages), or 64 blocked tasks per logical CPU (assuming 16 logical CPUs per NUMA node). So it's not likely some CPU goes idle waiting (when it could make progress) because of this limit: there are much more sleeping reclaim tasks than the number of CPU, so the task may well be blocked by some low level queue/lock anyway. Now !GFP_IOFS reclaims won't be waiting for GFP_IOFS reclaims to progress. They will be blocked only when there are too many concurrent !GFP_IOFS reclaims, however that's very unlikely because the IO-less direct reclaims is able to progress much more faster, and they won't deadlock each other. The threshold is raised high enough for them, so that there can be sufficient parallel progress of !GFP_IOFS reclaims. [akpm@linux-foundation.org: tweak comment] Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Torsten Kaiser <just.for.lkml@googlemail.com> Tested-by: NeilBrown <neilb@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d37dd5dc |
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18-Dec-2012 |
Fengguang Wu <fengguang.wu@intel.com> |
vmscan: comment too_many_isolated() Comment "Why it's doing so" rather than "What it does" as proposed by Andrew Morton. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
48fb2e24 |
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12-Dec-2012 |
Lai Jiangshan <laijs@cn.fujitsu.com> |
vmscan: use N_MEMORY instead N_HIGH_MEMORY N_HIGH_MEMORY stands for the nodes that has normal or high memory. N_MEMORY stands for the nodes that has any memory. The code here need to handle with the nodes which have memory, we should use N_MEMORY instead. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lin Feng <linfeng@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
6f6313d4 |
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11-Dec-2012 |
Jeff Liu <jeff.liu@oracle.com> |
mm/vmscan.c: try_to_freeze() returns boolean kswapd()->try_to_freeze() is defined to return a boolean, so it's better to use a bool to hold its return value. Signed-off-by: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e9868505 |
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11-Dec-2012 |
Rik van Riel <riel@redhat.com> |
mm,vmscan: only evict file pages when we have plenty If we have more inactive file pages than active file pages, we skip scanning the active file pages altogether, with the idea that we do not want to evict the working set when there is plenty of streaming IO in the cache. However, the code forgot to also skip scanning anonymous pages in that situation. That leads to the curious situation of keeping the active file pages protected from being paged out when there are lots of inactive file pages, while still scanning and evicting anonymous pages. This patch fixes that situation, by only evicting file pages when we have plenty of them and most are inactive. [akpm@linux-foundation.org: adjust comment layout] Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d84da3f9 |
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11-Dec-2012 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
mm: use IS_ENABLED(CONFIG_COMPACTION) instead of COMPACTION_BUILD We don't need custom COMPACTION_BUILD anymore, since we have handy IS_ENABLED(). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ed23ec4f |
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06-Dec-2012 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: fix inappropriate zone congestion clearing commit c702418f8a2f ("mm: vmscan: do not keep kswapd looping forever due to individual uncompactable zones") removed zone watermark checks from the compaction code in kswapd but left in the zone congestion clearing, which now happens unconditionally on higher order reclaim. This messes up the reclaim throttling logic for zones with dirty/writeback pages, where zones should only lose their congestion status when their watermarks have been restored. Remove the clearing from the zone compaction section entirely. The preliminary zone check and the reclaim loop in kswapd will clear it if the zone is considered balanced. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c702418f |
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04-Dec-2012 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: do not keep kswapd looping forever due to individual uncompactable zones When a zone meets its high watermark and is compactable in case of higher order allocations, it contributes to the percentage of the node's memory that is considered balanced. This requirement, that a node be only partially balanced, came about when kswapd was desparately trying to balance tiny zones when all bigger zones in the node had plenty of free memory. Arguably, the same should apply to compaction: if a significant part of the node is balanced enough to run compaction, do not get hung up on that tiny zone that might never get in shape. When the compaction logic in kswapd is reached, we know that at least 25% of the node's memory is balanced properly for compaction (see zone_balanced and pgdat_balanced). Remove the individual zone checks that restart the kswapd cycle. Otherwise, we may observe more endless looping in kswapd where the compaction code loops back to reclaim because of a single zone and reclaim does nothing because the node is considered balanced overall. See for example https://bugzilla.redhat.com/show_bug.cgi?id=866988 Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-and-tested-by: Thorsten Leemhuis <fedora@leemhuis.info> Reported-by: Jiri Slaby <jslaby@suse.cz> Tested-by: John Ellson <john.ellson@comcast.net> Tested-by: Zdenek Kabelac <zkabelac@redhat.com> Tested-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
60cefed4 |
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29-Nov-2012 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: fix endless loop in kswapd balancing Kswapd does not in all places have the same criteria for a balanced zone. Zones are only being reclaimed when their high watermark is breached, but compaction checks loop over the zonelist again when the zone does not meet the low watermark plus two times the size of the allocation. This gets kswapd stuck in an endless loop over a small zone, like the DMA zone, where the high watermark is smaller than the compaction requirement. Add a function, zone_balanced(), that checks the watermark, and, for higher order allocations, if compaction has enough free memory. Then use it uniformly to check for balanced zones. This makes sure that when the compaction watermark is not met, at least reclaim happens and progress is made - or the zone is declared unreclaimable at some point and skipped entirely. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: George Spelvin <linux@horizon.com> Reported-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Reported-by: Tomas Racek <tracek@redhat.com> Tested-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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50694c28 |
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26-Nov-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: check for fatal signals iff the process was throttled Commit 5515061d22f0 ("mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage") introduced a check for fatal signals after a process gets throttled for network storage. The intention was that if a process was throttled and got killed that it should not trigger the OOM killer. As pointed out by Minchan Kim and David Rientjes, this check is in the wrong place and too broad. If a system is in am OOM situation and a process is exiting, it can loop in __alloc_pages_slowpath() and calling direct reclaim in a loop. As the fatal signal is pending it returns 1 as if it is making forward progress and can effectively deadlock. This patch moves the fatal_signal_pending() check after throttling to throttle_direct_reclaim() where it belongs. If the process is killed while throttled, it will return immediately without direct reclaim except now it will have TIF_MEMDIE set and will use the PFMEMALLOC reserves. Minchan pointed out that it may be better to direct reclaim before returning to avoid using the reserves because there may be pages that can easily reclaim that would avoid using the reserves. However, we do no such targetted reclaim and there is no guarantee that suitable pages are available. As it is expected that this throttling happens when swap-over-NFS is used there is a possibility that the process will instead swap which may allocate network buffers from the PFMEMALLOC reserves. Hence, in the swap-over-nfs case where a process can be throtted and be killed it can use the reserves to exit or it can potentially use reserves to swap a few pages and then exit. This patch takes the option of using the reserves if necessary to allow the process exit quickly. If this patch passes review it should be considered a -stable candidate for 3.6. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
96710098 |
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16-Nov-2012 |
Mel Gorman <mgorman@suse.de> |
mm: revert "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures" Jiri Slaby reported the following: (It's an effective revert of "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures".) Given kswapd had hours of runtime in ps/top output yesterday in the morning and after the revert it's now 2 minutes in sum for the last 24h, I would say, it's gone. The intention of the patch in question was to compensate for the loss of lumpy reclaim. Part of the reason lumpy reclaim worked is because it aggressively reclaimed pages and this patch was meant to be a sane compromise. When compaction fails, it gets deferred and both compaction and reclaim/compaction is deferred avoid excessive reclaim. However, since commit c654345924f7 ("mm: remove __GFP_NO_KSWAPD"), kswapd is woken up each time and continues reclaiming which was not taken into account when the patch was developed. Attempts to address the problem ended up just changing the shape of the problem instead of fixing it. The release window gets closer and while a THP allocation failing is not a major problem, kswapd chewing up a lot of CPU is. This patch reverts commit 83fde0f22872 ("mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures") and will be revisited in the future. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Zdenek Kabelac <zkabelac@redhat.com> Tested-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Jiri Slaby <jirislaby@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b0a8cc58 |
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08-Nov-2012 |
Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com> |
mm: bugfix: set current->reclaim_state to NULL while returning from kswapd() In kswapd(), set current->reclaim_state to NULL before returning, as current->reclaim_state holds reference to variable on kswapd()'s stack. In rare cases, while returning from kswapd() during memory offlining, __free_slab() and freepages() can access the dangling pointer of current->reclaim_state. Signed-off-by: Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com> Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e46a2879 |
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08-Oct-2012 |
Minchan Kim <minchan@kernel.org> |
CMA: migrate mlocked pages Presently CMA cannot migrate mlocked pages so it ends up failing to allocate contiguous memory space. This patch makes mlocked pages be migrated out. Of course, it can affect realtime processes but in CMA usecase, contiguous memory allocation failing is far worse than access latency to an mlocked page being variable while CMA is running. If someone wants to make the system realtime, he shouldn't enable CMA because stalls can still happen at random times. [akpm@linux-foundation.org: tweak comment text, per Mel] Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
39b5f29a |
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08-Oct-2012 |
Hugh Dickins <hughd@google.com> |
mm: remove vma arg from page_evictable page_evictable(page, vma) is an irritant: almost all its callers pass NULL for vma. Remove the vma arg and use mlocked_vma_newpage(vma, page) explicitly in the couple of places it's needed. But in those places we don't even need page_evictable() itself! They're dealing with a freshly allocated anonymous page, which has no "mapping" and cannot be mlocked yet. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
62997027 |
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08-Oct-2012 |
Mel Gorman <mgorman@suse.de> |
mm: compaction: clear PG_migrate_skip based on compaction and reclaim activity Compaction caches if a pageblock was scanned and no pages were isolated so that the pageblocks can be skipped in the future to reduce scanning. This information is not cleared by the page allocator based on activity due to the impact it would have to the page allocator fast paths. Hence there is a requirement that something clear the cache or pageblocks will be skipped forever. Currently the cache is cleared if there were a number of recent allocation failures and it has not been cleared within the last 5 seconds. Time-based decisions like this are terrible as they have no relationship to VM activity and is basically a big hammer. Unfortunately, accurate heuristics would add cost to some hot paths so this patch implements a rough heuristic. There are two cases where the cache is cleared. 1. If a !kswapd process completes a compaction cycle (migrate and free scanner meet), the zone is marked compact_blockskip_flush. When kswapd goes to sleep, it will clear the cache. This is expected to be the common case where the cache is cleared. It does not really matter if kswapd happens to be asleep or going to sleep when the flag is set as it will be woken on the next allocation request. 2. If there have been multiple failures recently and compaction just finished being deferred then a process will clear the cache and start a full scan. This situation happens if there are multiple high-order allocation requests under heavy memory pressure. The clearing of the PG_migrate_skip bits and other scans is inherently racy but the race is harmless. For allocations that can fail such as THP, they will simply fail. For requests that cannot fail, they will retry the allocation. Tests indicated that scanning rates were roughly similar to when the time-based heuristic was used and the allocation success rates were similar. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Cc: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
02c6de8d |
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08-Oct-2012 |
Minchan Kim <minchan@kernel.org> |
mm: cma: discard clean pages during contiguous allocation instead of migration Drop clean cache pages instead of migration during alloc_contig_range() to minimise allocation latency by reducing the amount of migration that is necessary. It's useful for CMA because latency of migration is more important than evicting the background process's working set. In addition, as pages are reclaimed then fewer free pages for migration targets are required so it avoids memory reclaiming to get free pages, which is a contributory factor to increased latency. I measured elapsed time of __alloc_contig_migrate_range() which migrates 10M in 40M movable zone in QEMU machine. Before - 146ms, After - 7ms [akpm@linux-foundation.org: fix nommu build] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Mel Gorman <mgorman@suse.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Rik van Riel <riel@redhat.com> Tested-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d5dc0ad9 |
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08-Oct-2012 |
Gavin Shan <shangw@linux.vnet.ibm.com> |
mm/vmscan: fix error number for failed kthread Fix the return value while failing to create the kswapd kernel thread. Also, the error message is prioritized as KERN_ERR. Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
83fde0f2 |
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08-Oct-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures If allocation fails after compaction then compaction may be deferred for a number of allocation attempts. If there are subsequent failures, compact_defer_shift is increased to defer for longer periods. This patch uses that information to scale the number of pages reclaimed with compact_defer_shift until allocations succeed again. The rationale is that reclaiming the normal number of pages still allowed compaction to fail and its success depends on the number of pages. If it's failing, reclaim more pages until it succeeds again. Note that this is not implying that VM reclaim is not reclaiming enough pages or that its logic is broken. try_to_free_pages() always asks for SWAP_CLUSTER_MAX pages to be reclaimed regardless of order and that is what it does. Direct reclaim stops normally with this check. if (sc->nr_reclaimed >= sc->nr_to_reclaim) goto out; should_continue_reclaim delays when that check is made until a minimum number of pages for reclaim/compaction are reclaimed. It is possible that this patch could instead set nr_to_reclaim in try_to_free_pages() and drive it from there but that's behaves differently and not necessarily for the better. If driven from do_try_to_free_pages(), it is also possible that priorities will rise. When they reach DEF_PRIORITY-2, it will also start stalling and setting pages for immediate reclaim which is more disruptive than not desirable in this case. That is a more wide-reaching change that could cause another regression related to THP requests causing interactive jitter. [akpm@linux-foundation.org: fix build] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
18b48d58 |
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17-Sep-2012 |
Wen Congyang <wency@cn.fujitsu.com> |
memory hotplug: reset pgdat->kswapd to NULL if creating kernel thread fails If kthread_run() fails, pgdat->kswapd contains errno. When we stop this thread, we only check whether pgdat->kswapd is NULL and access it. If it contains errno, it will cause page fault. Reset pgdat->kswapd to NULL when creating kernel thread fails can avoid this problem. Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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69980e31 |
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31-Jul-2012 |
Tim Chen <tim.c.chen@linux.intel.com> |
memcg: gix memory accounting scalability in shrink_page_list I noticed in a multi-process parallel files reading benchmark I ran on a 8 socket machine, throughput slowed down by a factor of 8 when I ran the benchmark within a cgroup container. I traced the problem to the following code path (see below) when we are trying to reclaim memory from file cache. The res_counter_uncharge function is called on every page that's reclaimed and created heavy lock contention. The patch below allows the reclaimed pages to be uncharged from the resource counter in batch and recovered the regression. Tim 40.67% usemem [kernel.kallsyms] [k] _raw_spin_lock | --- _raw_spin_lock | |--92.61%-- res_counter_uncharge | | | |--100.00%-- __mem_cgroup_uncharge_common | | | | | |--100.00%-- mem_cgroup_uncharge_cache_page | | | __remove_mapping | | | shrink_page_list | | | shrink_inactive_list | | | shrink_mem_cgroup_zone | | | shrink_zone | | | do_try_to_free_pages | | | try_to_free_pages | | | __alloc_pages_nodemask | | | alloc_pages_current Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c3b94f44 |
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31-Jul-2012 |
Hugh Dickins <hughd@google.com> |
memcg: further prevent OOM with too many dirty pages The may_enter_fs test turns out to be too restrictive: though I saw no problem with it when testing on 3.5-rc6, it very soon OOMed when I tested on 3.5-rc6-mm1. I don't know what the difference there is, perhaps I just slightly changed the way I started off the testing: dd if=/dev/zero of=/mnt/temp bs=1M count=1024; rm -f /mnt/temp; sync repeatedly, in 20M memory.limit_in_bytes cgroup to ext4 on USB stick. ext4 (and gfs2 and xfs) turn out to allocate new pages for writing with AOP_FLAG_NOFS: that seems a little worrying, and it's unclear to me why the transaction needs to be started even before allocating pagecache memory. But it may not be worth worrying about these days: if direct reclaim avoids FS writeback, does __GFP_FS now mean anything? Anyway, we insisted on the may_enter_fs test to avoid hangs with the loop device; but since that also masks off __GFP_IO, we can test for __GFP_IO directly, ignoring may_enter_fs and __GFP_FS. But even so, the test still OOMs sometimes: when originally testing on 3.5-rc6, it OOMed about one time in five or ten; when testing just now on 3.5-rc6-mm1, it OOMed on the first iteration. This residual problem comes from an accumulation of pages under ordinary writeback, not marked PageReclaim, so rightly not causing the memcg check to wait on their writeback: these too can prevent shrink_page_list() from freeing any pages, so many times that memcg reclaim fails and OOMs. Deal with these in the same way as direct reclaim now deals with dirty FS pages: mark them PageReclaim. It is appropriate to rotate these to tail of list when writepage completes, but more importantly, the PageReclaim flag makes memcg reclaim wait on them if encountered again. Increment NR_VMSCAN_IMMEDIATE? That's arguable: I chose not. Setting PageReclaim here may occasionally race with end_page_writeback() clearing it: lru_deactivate_fn() already faced the same race, and correctly concluded that the window is small and the issue non-critical. With these changes, the test runs indefinitely without OOMing on ext4, ext3 and ext2: I'll move on to test with other filesystems later. Trivia: invert conditions for a clearer block without an else, and goto keep_locked to do the unlock_page. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e62e384e |
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31-Jul-2012 |
Michal Hocko <mhocko@suse.cz> |
memcg: prevent OOM with too many dirty pages The current implementation of dirty pages throttling is not memcg aware which makes it easy to have memcg LRUs full of dirty pages. Without throttling, these LRUs can be scanned faster than the rate of writeback, leading to memcg OOM conditions when the hard limit is small. This patch fixes the problem by throttling the allocating process (possibly a writer) during the hard limit reclaim by waiting on PageReclaim pages. We are waiting only for PageReclaim pages because those are the pages that made one full round over LRU and that means that the writeback is much slower than scanning. The solution is far from being ideal - long term solution is memcg aware dirty throttling - but it is meant to be a band aid until we have a real fix. We are seeing this happening during nightly backups which are placed into containers to prevent from eviction of the real working set. The change affects only memcg reclaim and only when we encounter PageReclaim pages which is a signal that the reclaim doesn't catch up on with the writers so somebody should be throttled. This could be potentially unfair because it could be somebody else from the group who gets throttled on behalf of the writer but as writers need to allocate as well and they allocate in higher rate the probability that only innocent processes would be penalized is not that high. I have tested this change by a simple dd copying /dev/zero to tmpfs or ext3 running under small memcg (1G copy under 5M, 60M, 300M and 2G containers) and dd got killed by OOM killer every time. With the patch I could run the dd with the same size under 5M controller without any OOM. The issue is more visible with slower devices for output. * With the patch ================ * tmpfs size=2G --------------- $ vim cgroup_cache_oom_test.sh $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 30.4049 s, 34.5 MB/s $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 31.4561 s, 33.3 MB/s $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 20.4618 s, 51.2 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 1.42172 s, 738 MB/s * ext3 ------ $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 27.9547 s, 37.5 MB/s $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 30.3221 s, 34.6 MB/s $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 24.5764 s, 42.7 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 3.35828 s, 312 MB/s * Without the patch =================== * tmpfs size=2G --------------- $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group ./cgroup_cache_oom_test.sh: line 46: 4668 Killed dd if=/dev/zero of=$OUT/zero bs=1M count=$count $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 25.4989 s, 41.1 MB/s $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 24.3928 s, 43.0 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 1.49797 s, 700 MB/s * ext3 ------ $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group ./cgroup_cache_oom_test.sh: line 46: 4689 Killed dd if=/dev/zero of=$OUT/zero bs=1M count=$count $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group ./cgroup_cache_oom_test.sh: line 46: 4692 Killed dd if=/dev/zero of=$OUT/zero bs=1M count=$count $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 20.248 s, 51.8 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 2.85201 s, 368 MB/s [akpm@linux-foundation.org: tweak changelog, reordered the test to optimize for CONFIG_CGROUP_MEM_RES_CTLR=n] [hughd@google.com: fix deadlock with loop driver] Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
68243e76 |
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31-Jul-2012 |
Mel Gorman <mgorman@suse.de> |
mm: account for the number of times direct reclaimers get throttled Under significant pressure when writing back to network-backed storage, direct reclaimers may get throttled. This is expected to be a short-lived event and the processes get woken up again but processes do get stalled. This patch counts how many times such stalling occurs. It's up to the administrator whether to reduce these stalls by increasing min_free_kbytes. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5515061d |
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31-Jul-2012 |
Mel Gorman <mgorman@suse.de> |
mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage If swap is backed by network storage such as NBD, there is a risk that a large number of reclaimers can hang the system by consuming all PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune min_free_kbytes in advance which is a bit fragile. This patch throttles direct reclaimers if half the PF_MEMALLOC reserves are in use. If the system is routinely getting throttled the system administrator can increase min_free_kbytes so degradation is smoother but the system will keep running. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c255a458 |
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31-Jul-2012 |
Andrew Morton <akpm@linux-foundation.org> |
memcg: rename config variables Sanity: CONFIG_CGROUP_MEM_RES_CTLR -> CONFIG_MEMCG CONFIG_CGROUP_MEM_RES_CTLR_SWAP -> CONFIG_MEMCG_SWAP CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED -> CONFIG_MEMCG_SWAP_ENABLED CONFIG_CGROUP_MEM_RES_CTLR_KMEM -> CONFIG_MEMCG_KMEM [mhocko@suse.cz: fix missed bits] Cc: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1c7e7f6c |
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17-Jul-2012 |
Aaditya Kumar <aaditya.kumar.30@gmail.com> |
mm: fix lost kswapd wakeup in kswapd_stop() Offlining memory may block forever, waiting for kswapd() to wake up because kswapd() does not check the event kthread->should_stop before sleeping. The proper pattern, from Documentation/memory-barriers.txt, is: --- waker --- event_indicated = 1; wake_up_process(event_daemon); --- sleeper --- for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (event_indicated) break; schedule(); } set_current_state() may be wrapped by: prepare_to_wait(); In the kswapd() case, event_indicated is kthread->should_stop. === offlining memory (waker) === kswapd_stop() kthread_stop() kthread->should_stop = 1 wake_up_process() wait_for_completion() === kswapd_try_to_sleep (sleeper) === kswapd_try_to_sleep() prepare_to_wait() . . schedule() . . finish_wait() The schedule() needs to be protected by a test of kthread->should_stop, which is wrapped by kthread_should_stop(). Reproducer: Do heavy file I/O in background. Do a memory offline/online in a tight loop Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d8adde17 |
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11-Jul-2012 |
Jiang Liu <jiang.liu@huawei.com> |
memory hotplug: fix invalid memory access caused by stale kswapd pointer kswapd_stop() is called to destroy the kswapd work thread when all memory of a NUMA node has been offlined. But kswapd_stop() only terminates the work thread without resetting NODE_DATA(nid)->kswapd to NULL. The stale pointer will prevent kswapd_run() from creating a new work thread when adding memory to the memory-less NUMA node again. Eventually the stale pointer may cause invalid memory access. An example stack dump as below. It's reproduced with 2.6.32, but latest kernel has the same issue. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff81051a94>] exit_creds+0x12/0x78 PGD 0 Oops: 0000 [#1] SMP last sysfs file: /sys/devices/system/memory/memory391/state CPU 11 Modules linked in: cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq microcode fuse loop dm_mod tpm_tis rtc_cmos i2c_i801 rtc_core tpm serio_raw pcspkr sg tpm_bios igb i2c_core iTCO_wdt rtc_lib mptctl iTCO_vendor_support button dca bnx2 usbhid hid uhci_hcd ehci_hcd usbcore sd_mod crc_t10dif edd ext3 mbcache jbd fan ide_pci_generic ide_core ata_generic ata_piix libata thermal processor thermal_sys hwmon mptsas mptscsih mptbase scsi_transport_sas scsi_mod Pid: 7949, comm: sh Not tainted 2.6.32.12-qiuxishi-5-default #92 Tecal RH2285 RIP: 0010:exit_creds+0x12/0x78 RSP: 0018:ffff8806044f1d78 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff880604f22140 RCX: 0000000000019502 RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000 RBP: ffff880604f22150 R08: 0000000000000000 R09: ffffffff81a4dc10 R10: 00000000000032a0 R11: ffff880006202500 R12: 0000000000000000 R13: 0000000000c40000 R14: 0000000000008000 R15: 0000000000000001 FS: 00007fbc03d066f0(0000) GS:ffff8800282e0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 000000060f029000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process sh (pid: 7949, threadinfo ffff8806044f0000, task ffff880603d7c600) Stack: ffff880604f22140 ffffffff8103aac5 ffff880604f22140 ffffffff8104d21e ffff880006202500 0000000000008000 0000000000c38000 ffffffff810bd5b1 0000000000000000 ffff880603d7c600 00000000ffffdd29 0000000000000003 Call Trace: __put_task_struct+0x5d/0x97 kthread_stop+0x50/0x58 offline_pages+0x324/0x3da memory_block_change_state+0x179/0x1db store_mem_state+0x9e/0xbb sysfs_write_file+0xd0/0x107 vfs_write+0xad/0x169 sys_write+0x45/0x6e system_call_fastpath+0x16/0x1b Code: ff 4d 00 0f 94 c0 84 c0 74 08 48 89 ef e8 1f fd ff ff 5b 5d 31 c0 41 5c c3 53 48 8b 87 20 06 00 00 48 89 fb 48 8b bf 18 06 00 00 <8b> 00 48 c7 83 18 06 00 00 00 00 00 00 f0 ff 0f 0f 94 c0 84 c0 RIP exit_creds+0x12/0x78 RSP <ffff8806044f1d78> CR2: 0000000000000000 [akpm@linux-foundation.org: add pglist_data.kswapd locking comments] Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ab8704b8 |
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16-Jun-2012 |
Wanpeng Li <liwp@linux.vnet.ibm.com> |
mm/vmscan: cleanup comment error in balance_pgdat Signed-off-by: Wanpeng Li <liwp.linux@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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be7bd59d |
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14-Jun-2012 |
Wanpeng Li <liwp@linux.vnet.ibm.com> |
mm: fix page reclaim comment error Since there are five lists in LRU cache, the array nr in get_scan_count should be: nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan nr[2] = file inactive pages to scan; nr[3] = file active pages to scan Signed-off-by: Wanpeng Li <liwp.linux@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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fa9add64 |
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29-May-2012 |
Hugh Dickins <hughd@google.com> |
mm/memcg: apply add/del_page to lruvec Take lruvec further: pass it instead of zone to add_page_to_lru_list() and del_page_from_lru_list(); and pagevec_lru_move_fn() pass lruvec down to its target functions. This cleanup eliminates a swathe of cruft in memcontrol.c, including mem_cgroup_lru_add_list(), mem_cgroup_lru_del_list() and mem_cgroup_lru_move_lists() - which never actually touched the lists. In their place, mem_cgroup_page_lruvec() to decide the lruvec, previously a side-effect of add, and mem_cgroup_update_lru_size() to maintain the lru_size stats. Whilst these are simplifications in their own right, the goal is to bring the evaluation of lruvec next to the spin_locking of the lrus, in preparation for a future patch. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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75b00af7 |
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29-May-2012 |
Hugh Dickins <hughd@google.com> |
mm: trivial cleanups in vmscan.c Utter trivia in mm/vmscan.c, mostly just reducing the linecount slightly; most exciting change being get_scan_count() calling vmscan_swappiness() once instead of twice. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4d7dcca2 |
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29-May-2012 |
Hugh Dickins <hughd@google.com> |
mm/memcg: get_lru_size not get_lruvec_size Konstantin just introduced mem_cgroup_get_lruvec_size() and get_lruvec_size(), I'm about to add mem_cgroup_update_lru_size(): but we're dealing with the same thing, lru_size[lru]. We ought to agree on the naming, and I do think lru_size is the more correct: so rename his ones to get_lru_size(). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f9be23d6 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: kill struct mem_cgroup_zone Kill struct mem_cgroup_zone and rename shrink_mem_cgroup_zone() to shrink_lruvec(), it always shrinks one lruvec which it takes as an argument. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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90bdcfaf |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push lruvec pointer into should_continue_reclaim() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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90126375 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push lruvec pointer into get_scan_count() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1a93be0e |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push lruvec pointer into shrink_list() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c56d5c7d |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push lruvec pointer into inactive_list_is_low() Switch mem_cgroup_inactive_anon_is_low() to lruvec pointers, mem_cgroup_get_lruvec_size() is more effective than mem_cgroup_zone_nr_lru_pages() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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074291fe |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: replace zone_nr_lru_pages() with get_lruvec_size() If memory cgroup is enabled we always use lruvecs which are embedded into struct mem_cgroup_per_zone, so we can reach lru_size counters via container_of(). Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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27ac81d8 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push lruvec pointer into putback_inactive_pages() As zone_reclaim_stat is now located in the lruvec, we can reach it directly. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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95d918fc |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: remove update_isolated_counts() update_isolated_counts() is no longer required, because lumpy-reclaim was removed. Insanity is over, now there is only one kind of inactive page. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6a18adb3 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push zone pointer into shrink_page_list() It doesn't need a pointer to the cgroup - pointer to the zone is enough. This patch also kills the "mz" argument of page_check_references() - it is unused after "mm: memcg: count pte references from every member of the reclaimed hierarch" Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5dc35979 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: push lruvec pointer into isolate_lru_pages() Move the mem_cgroup_zone_lruvec() call from isolate_lru_pages() into shrink_[in]active_list(). Further patches push it to shrink_zone() step by step. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9e3b2f8c |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/vmscan: store "priority" in struct scan_control In memory reclaim some function have too many arguments - "priority" is one of them. It can be stored in struct scan_control - we construct them on the same level. Instead of an open coded loop we set the initial sc.priority, and do_try_to_free_pages() decreases it down to zero. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3d58ab5c |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/memcg: use vm_swappiness from target memory cgroup Use vm_swappiness from memory cgroup which is triggered this memory reclaim. This is more reasonable and allows to kill one argument. [akpm@linux-foundation.org: fix build (patch skew)] Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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89abfab1 |
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29-May-2012 |
Hugh Dickins <hughd@google.com> |
mm/memcg: move reclaim_stat into lruvec With mem_cgroup_disabled() now explicit, it becomes clear that the zone_reclaim_stat structure actually belongs in lruvec, per-zone when memcg is disabled but per-memcg per-zone when it's enabled. We can delete mem_cgroup_get_reclaim_stat(), and change update_page_reclaim_stat() to update just the one set of stats, the one which get_scan_count() will actually use. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c3c787e8 |
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29-May-2012 |
Hugh Dickins <hughd@google.com> |
mm/memcg: scanning_global_lru means mem_cgroup_disabled Although one has to admire the skill with which it has been concealed, scanning_global_lru(mz) is actually just an interesting way to test mem_cgroup_disabled(). Too many developer hours have been wasted on confusing it with global_reclaim(): just use mem_cgroup_disabled(). Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bbf808ed |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm/memcg: kill mem_cgroup_lru_del() This patch kills mem_cgroup_lru_del(), we can use mem_cgroup_lru_del_list() instead. On 0-order isolation we already have right lru list id. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f3fd4a61 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm: remove lru type checks from __isolate_lru_page() After patch "mm: forbid lumpy-reclaim in shrink_active_list()" we can completely remove anon/file and active/inactive lru type filters from __isolate_lru_page(), because isolation for 0-order reclaim always isolates pages from right lru list. And pages-isolation for lumpy shrink_inactive_list() or memory-compaction anyway allowed to isolate pages from all evictable lru lists. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3cb99451 |
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29-May-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm: push lru index into shrink_[in]active_list() Let's toss lru index through call stack to isolate_lru_pages(), this is better than its reconstructing from individual bits. [akpm@linux-foundation.org: fix kerneldoc, per Minchan] Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fe35004f |
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29-May-2012 |
Satoru Moriya <satoru.moriya@hds.com> |
mm: avoid swapping out with swappiness==0 Sometimes we'd like to avoid swapping out anonymous memory. In particular, avoid swapping out pages of important process or process groups while there is a reasonable amount of pagecache on RAM so that we can satisfy our customers' requirements. OTOH, we can control how aggressive the kernel will swap memory pages with /proc/sys/vm/swappiness for global and /sys/fs/cgroup/memory/memory.swappiness for each memcg. But with current reclaim implementation, the kernel may swap out even if we set swappiness=0 and there is pagecache in RAM. This patch changes the behavior with swappiness==0. If we set swappiness==0, the kernel does not swap out completely (for global reclaim until the amount of free pages and filebacked pages in a zone has been reduced to something very very small (nr_free + nr_filebacked < high watermark)). Signed-off-by: Satoru Moriya <satoru.moriya@hds.com> Acked-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e4898273 |
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29-May-2012 |
Michal Hocko <mhocko@suse.cz> |
mm: consider all swapped back pages in used-once logic Commit 645747462435 ("vmscan: detect mapped file pages used only once") made mapped pages have another round in inactive list because they might be just short lived and so we could consider them again next time. This heuristic helps to reduce pressure on the active list with a streaming IO worklods. This patch fixes a regression introduced by this commit for heavy shmem based workloads because unlike Anon pages, which are excluded from this heuristic because they are usually long lived, shmem pages are handled as a regular page cache. This doesn't work quite well, unfortunately, if the workload is mostly backed by shmem (in memory database sitting on 80% of memory) with a streaming IO in the background (backup - up to 20% of memory). Anon inactive list is full of (dirty) shmem pages when watermarks are hit. Shmem pages are kept in the inactive list (they are referenced) in the first round and it is hard to reclaim anything else so we reach lower scanning priorities very quickly which leads to an excessive swap out. Let's fix this by excluding all swap backed pages (they tend to be long lived wrt. the regular page cache anyway) from used-once heuristic and rather activate them if they are referenced. The customer's workload is shmem backed database (80% of RAM) and they are measuring transactions/s with an IO in the background (20%). Transactions touch more or less random rows in the table. The transaction rate fell by a factor of 3 (in the worst case) because of commit 64574746. This patch restores the previous numbers. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: <stable@vger.kernel.org> [2.6.34+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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096a7cf4 |
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29-May-2012 |
Ying Han <yinghan@google.com> |
mm: rename is_mlocked_vma() to mlocked_vma_newpage() Andrew pointed out that the is_mlocked_vma() is misnamed. A function with name like that would expect bool return and no side-effects. Since it is called on the fault path for new page, rename it in this patch. Signed-off-by: Ying Han <yinghan@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com> Reviewed-by: Minchan Kim <minchan@kernel.org> [akpm@linux-foundation.org: s/mlock_vma_newpage/mlock_vma_newpage/, per Minchan] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c3ac9a8a |
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29-May-2012 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcg: count pte references from every member of the reclaimed hierarchy The rmap walker checking page table references has historically ignored references from VMAs that were not part of the memcg that was being reclaimed during memcg hard limit reclaim. When transitioning global reclaim to memcg hierarchy reclaim, I missed that bit and now references from outside a memcg are ignored even during global reclaim. Reverting back to traditional behaviour - count all references during global reclaim and only mind references of the memcg being reclaimed during limit reclaim would be one option. However, the more generic idea is to ignore references exactly then when they are outside the hierarchy that is currently under reclaim; because only then will their reclamation be of any use to help the pressure situation. It makes no sense to ignore references from a sibling memcg and then evict a page that will be immediately refaulted by that sibling which contributes to the same usage of the common ancestor under reclaim. The solution: make the rmap walker ignore references from VMAs that are not part of the hierarchy that is being reclaimed. Flat limit reclaim will stay the same, hierarchical limit reclaim will mind the references only to pages that the hierarchy owns. Global reclaim, since it reclaims from all memcgs, will be fixed to regard all references. [akpm@linux-foundation.org: name the args in the declaration] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Konstantin Khlebnikov<khlebnikov@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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23b9da55 |
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29-May-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: remove reclaim_mode_t There is little motiviation for reclaim_mode_t once RECLAIM_MODE_[A]SYNC and lumpy reclaim have been removed. This patch gets rid of reclaim_mode_t as well and improves the documentation about what reclaim/compaction is and when it is triggered. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Hugh Dickins <hughd@google.com> Cc: Ying Han <yinghan@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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41ac1999 |
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29-May-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not stall on writeback during memory compaction This patch stops reclaim/compaction entering sync reclaim as this was only intended for lumpy reclaim and an oversight. Page migration has its own logic for stalling on writeback pages if necessary and memory compaction is already using it. Waiting on page writeback is bad for a number of reasons but the primary one is that waiting on writeback to a slow device like USB can take a considerable length of time. Page reclaim instead uses wait_iff_congested() to throttle if too many dirty pages are being scanned. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Hugh Dickins <hughd@google.com> Cc: Ying Han <yinghan@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c53919ad |
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29-May-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: remove lumpy reclaim This series removes lumpy reclaim and some stalling logic that was unintentionally being used by memory compaction. The end result is that stalling on dirty pages during page reclaim now depends on wait_iff_congested(). Four kernels were compared 3.3.0 vanilla 3.4.0-rc2 vanilla 3.4.0-rc2 lumpyremove-v2 is patch one from this series 3.4.0-rc2 nosync-v2r3 is the full series Removing lumpy reclaim saves almost 900 bytes of text whereas the full series removes 1200 bytes. text data bss dec hex filename 6740375 1927944 2260992 10929311 a6c49f vmlinux-3.4.0-rc2-vanilla 6739479 1927944 2260992 10928415 a6c11f vmlinux-3.4.0-rc2-lumpyremove-v2 6739159 1927944 2260992 10928095 a6bfdf vmlinux-3.4.0-rc2-nosync-v2 There are behaviour changes in the series and so tests were run with monitoring of ftrace events. This disrupts results so the performance results are distorted but the new behaviour should be clearer. fs-mark running in a threaded configuration showed little of interest as it did not push reclaim aggressively FS-Mark Multi Threaded 3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3 Files/s min 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) Files/s mean 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) Files/s stddev 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Files/s max 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) 3.20 ( 0.00%) Overhead min 508667.00 ( 0.00%) 521350.00 (-2.49%) 544292.00 (-7.00%) 547168.00 (-7.57%) Overhead mean 551185.00 ( 0.00%) 652690.73 (-18.42%) 991208.40 (-79.83%) 570130.53 (-3.44%) Overhead stddev 18200.69 ( 0.00%) 331958.29 (-1723.88%) 1579579.43 (-8578.68%) 9576.81 (47.38%) Overhead max 576775.00 ( 0.00%) 1846634.00 (-220.17%) 6901055.00 (-1096.49%) 585675.00 (-1.54%) MMTests Statistics: duration Sys Time Running Test (seconds) 309.90 300.95 307.33 298.95 User+Sys Time Running Test (seconds) 319.32 309.67 315.69 307.51 Total Elapsed Time (seconds) 1187.85 1193.09 1191.98 1193.73 MMTests Statistics: vmstat Page Ins 80532 82212 81420 79480 Page Outs 111434984 111456240 111437376 111582628 Swap Ins 0 0 0 0 Swap Outs 0 0 0 0 Direct pages scanned 44881 27889 27453 34843 Kswapd pages scanned 25841428 25860774 25861233 25843212 Kswapd pages reclaimed 25841393 25860741 25861199 25843179 Direct pages reclaimed 44881 27889 27453 34843 Kswapd efficiency 99% 99% 99% 99% Kswapd velocity 21754.791 21675.460 21696.029 21649.127 Direct efficiency 100% 100% 100% 100% Direct velocity 37.783 23.375 23.031 29.188 Percentage direct scans 0% 0% 0% 0% ftrace showed that there was no stalling on writeback or pages submitted for IO from reclaim context. postmark was similar and while it was more interesting, it also did not push reclaim heavily. POSTMARK 3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3 Transactions per second: 16.00 ( 0.00%) 20.00 (25.00%) 18.00 (12.50%) 17.00 ( 6.25%) Data megabytes read per second: 18.80 ( 0.00%) 24.27 (29.10%) 22.26 (18.40%) 20.54 ( 9.26%) Data megabytes written per second: 35.83 ( 0.00%) 46.25 (29.08%) 42.42 (18.39%) 39.14 ( 9.24%) Files created alone per second: 28.00 ( 0.00%) 38.00 (35.71%) 34.00 (21.43%) 30.00 ( 7.14%) Files create/transact per second: 8.00 ( 0.00%) 10.00 (25.00%) 9.00 (12.50%) 8.00 ( 0.00%) Files deleted alone per second: 556.00 ( 0.00%) 1224.00 (120.14%) 3062.00 (450.72%) 6124.00 (1001.44%) Files delete/transact per second: 8.00 ( 0.00%) 10.00 (25.00%) 9.00 (12.50%) 8.00 ( 0.00%) MMTests Statistics: duration Sys Time Running Test (seconds) 113.34 107.99 109.73 108.72 User+Sys Time Running Test (seconds) 145.51 139.81 143.32 143.55 Total Elapsed Time (seconds) 1159.16 899.23 980.17 1062.27 MMTests Statistics: vmstat Page Ins 13710192 13729032 13727944 13760136 Page Outs 43071140 42987228 42733684 42931624 Swap Ins 0 0 0 0 Swap Outs 0 0 0 0 Direct pages scanned 0 0 0 0 Kswapd pages scanned 9941613 9937443 9939085 9929154 Kswapd pages reclaimed 9940926 9936751 9938397 9928465 Direct pages reclaimed 0 0 0 0 Kswapd efficiency 99% 99% 99% 99% Kswapd velocity 8576.567 11051.058 10140.164 9347.109 Direct efficiency 100% 100% 100% 100% Direct velocity 0.000 0.000 0.000 0.000 It looks like here that the full series regresses performance but as ftrace showed no usage of wait_iff_congested() or sync reclaim I am assuming it's a disruption due to monitoring. Other data such as memory usage, page IO, swap IO all looked similar. Running a benchmark with a plain DD showed nothing very interesting. The full series stalled in wait_iff_congested() slightly less but stall times on vanilla kernels were marginal. Running a benchmark that hammered on file-backed mappings showed stalls due to congestion but not in sync writebacks MICRO 3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3 MMTests Statistics: duration Sys Time Running Test (seconds) 308.13 294.50 298.75 299.53 User+Sys Time Running Test (seconds) 330.45 316.28 318.93 320.79 Total Elapsed Time (seconds) 1814.90 1833.88 1821.14 1832.91 MMTests Statistics: vmstat Page Ins 108712 120708 97224 110344 Page Outs 155514576 156017404 155813676 156193256 Swap Ins 0 0 0 0 Swap Outs 0 0 0 0 Direct pages scanned 2599253 1550480 2512822 2414760 Kswapd pages scanned 69742364 71150694 68839041 69692533 Kswapd pages reclaimed 34824488 34773341 34796602 34799396 Direct pages reclaimed 53693 94750 61792 75205 Kswapd efficiency 49% 48% 50% 49% Kswapd velocity 38427.662 38797.901 37799.972 38022.889 Direct efficiency 2% 6% 2% 3% Direct velocity 1432.174 845.464 1379.807 1317.446 Percentage direct scans 3% 2% 3% 3% Page writes by reclaim 0 0 0 0 Page writes file 0 0 0 0 Page writes anon 0 0 0 0 Page reclaim immediate 0 0 0 1218 Page rescued immediate 0 0 0 0 Slabs scanned 15360 16384 13312 16384 Direct inode steals 0 0 0 0 Kswapd inode steals 4340 4327 1630 4323 FTrace Reclaim Statistics: congestion_wait Direct number congest waited 0 0 0 0 Direct time congest waited 0ms 0ms 0ms 0ms Direct full congest waited 0 0 0 0 Direct number conditional waited 900 870 754 789 Direct time conditional waited 0ms 0ms 0ms 20ms Direct full conditional waited 0 0 0 0 KSwapd number congest waited 2106 2308 2116 1915 KSwapd time congest waited 139924ms 157832ms 125652ms 132516ms KSwapd full congest waited 1346 1530 1202 1278 KSwapd number conditional waited 12922 16320 10943 14670 KSwapd time conditional waited 0ms 0ms 0ms 0ms KSwapd full conditional waited 0 0 0 0 Reclaim statistics are not radically changed. The stall times in kswapd are massive but it is clear that it is due to calls to congestion_wait() and that is almost certainly the call in balance_pgdat(). Otherwise stalls due to dirty pages are non-existant. I ran a benchmark that stressed high-order allocation. This is very artifical load but was used in the past to evaluate lumpy reclaim and compaction. Generally I look at allocation success rates and latency figures. STRESS-HIGHALLOC 3.3.0-vanilla rc2-vanilla lumpyremove-v2r3 nosync-v2r3 Pass 1 81.00 ( 0.00%) 28.00 (-53.00%) 24.00 (-57.00%) 28.00 (-53.00%) Pass 2 82.00 ( 0.00%) 39.00 (-43.00%) 38.00 (-44.00%) 43.00 (-39.00%) while Rested 88.00 ( 0.00%) 87.00 (-1.00%) 88.00 ( 0.00%) 88.00 ( 0.00%) MMTests Statistics: duration Sys Time Running Test (seconds) 740.93 681.42 685.14 684.87 User+Sys Time Running Test (seconds) 2922.65 3269.52 3281.35 3279.44 Total Elapsed Time (seconds) 1161.73 1152.49 1159.55 1161.44 MMTests Statistics: vmstat Page Ins 4486020 2807256 2855944 2876244 Page Outs 7261600 7973688 7975320 7986120 Swap Ins 31694 0 0 0 Swap Outs 98179 0 0 0 Direct pages scanned 53494 57731 34406 113015 Kswapd pages scanned 6271173 1287481 1278174 1219095 Kswapd pages reclaimed 2029240 1281025 1260708 1201583 Direct pages reclaimed 1468 14564 16649 92456 Kswapd efficiency 32% 99% 98% 98% Kswapd velocity 5398.133 1117.130 1102.302 1049.641 Direct efficiency 2% 25% 48% 81% Direct velocity 46.047 50.092 29.672 97.306 Percentage direct scans 0% 4% 2% 8% Page writes by reclaim 1616049 0 0 0 Page writes file 1517870 0 0 0 Page writes anon 98179 0 0 0 Page reclaim immediate 103778 27339 9796 17831 Page rescued immediate 0 0 0 0 Slabs scanned 1096704 986112 980992 998400 Direct inode steals 223 215040 216736 247881 Kswapd inode steals 175331 61548 68444 63066 Kswapd skipped wait 21991 0 1 0 THP fault alloc 1 135 125 134 THP collapse alloc 393 311 228 236 THP splits 25 13 7 8 THP fault fallback 0 0 0 0 THP collapse fail 3 5 7 7 Compaction stalls 865 1270 1422 1518 Compaction success 370 401 353 383 Compaction failures 495 869 1069 1135 Compaction pages moved 870155 3828868 4036106 4423626 Compaction move failure 26429 23865 29742 27514 Success rates are completely hosed for 3.4-rc2 which is almost certainly due to commit fe2c2a106663 ("vmscan: reclaim at order 0 when compaction is enabled"). I expected this would happen for kswapd and impair allocation success rates (https://lkml.org/lkml/2012/1/25/166) but I did not anticipate this much a difference: 80% less scanning, 37% less reclaim by kswapd In comparison, reclaim/compaction is not aggressive and gives up easily which is the intended behaviour. hugetlbfs uses __GFP_REPEAT and would be much more aggressive about reclaim/compaction than THP allocations are. The stress test above is allocating like neither THP or hugetlbfs but is much closer to THP. Mainline is now impaired in terms of high order allocation under heavy load although I do not know to what degree as I did not test with __GFP_REPEAT. Keep this in mind for bugs related to hugepage pool resizing, THP allocation and high order atomic allocation failures from network devices. In terms of congestion throttling, I see the following for this test FTrace Reclaim Statistics: congestion_wait Direct number congest waited 3 0 0 0 Direct time congest waited 0ms 0ms 0ms 0ms Direct full congest waited 0 0 0 0 Direct number conditional waited 957 512 1081 1075 Direct time conditional waited 0ms 0ms 0ms 0ms Direct full conditional waited 0 0 0 0 KSwapd number congest waited 36 4 3 5 KSwapd time congest waited 3148ms 400ms 300ms 500ms KSwapd full congest waited 30 4 3 5 KSwapd number conditional waited 88514 197 332 542 KSwapd time conditional waited 4980ms 0ms 0ms 0ms KSwapd full conditional waited 49 0 0 0 The "conditional waited" times are the most interesting as this is directly impacted by the number of dirty pages encountered during scan. As lumpy reclaim is no longer scanning contiguous ranges, it is finding fewer dirty pages. This brings wait times from about 5 seconds to 0. kswapd itself is still calling congestion_wait() so it'll still stall but it's a lot less. In terms of the type of IO we were doing, I see this FTrace Reclaim Statistics: mm_vmscan_writepage Direct writes anon sync 0 0 0 0 Direct writes anon async 0 0 0 0 Direct writes file sync 0 0 0 0 Direct writes file async 0 0 0 0 Direct writes mixed sync 0 0 0 0 Direct writes mixed async 0 0 0 0 KSwapd writes anon sync 0 0 0 0 KSwapd writes anon async 91682 0 0 0 KSwapd writes file sync 0 0 0 0 KSwapd writes file async 822629 0 0 0 KSwapd writes mixed sync 0 0 0 0 KSwapd writes mixed async 0 0 0 0 In 3.2, kswapd was doing a bunch of async writes of pages but reclaim/compaction was never reaching a point where it was doing sync IO. This does not guarantee that reclaim/compaction was not calling wait_on_page_writeback() but I would consider it unlikely. It indicates that merging patches 2 and 3 to stop reclaim/compaction calling wait_on_page_writeback() should be safe. This patch: Lumpy reclaim had a purpose but in the mind of some, it was to kick the system so hard it trashed. For others the purpose was to complicate vmscan.c. Over time it was giving softer shoes and a nicer attitude but memory compaction needs to step up and replace it so this patch sends lumpy reclaim to the farm. The tracepoint format changes for isolating LRU pages with this patch applied. Furthermore reclaim/compaction can no longer queue dirty pages in pageout() if the underlying BDI is congested. Lumpy reclaim used this logic and reclaim/compaction was using it in error. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Hugh Dickins <hughd@google.com> Cc: Ying Han <yinghan@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e709ffd6 |
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29-May-2012 |
Rik van Riel <riel@redhat.com> |
mm: remove swap token code The swap token code no longer fits in with the current VM model. It does not play well with cgroups or the better NUMA placement code in development, since we have only one swap token globally. It also has the potential to mess with scalability of the system, by increasing the number of non-reclaimable pages on the active and inactive anon LRU lists. Last but not least, the swap token code has been broken for a year without complaints, as reported by Konstantin Khlebnikov. This suggests we no longer have much use for it. The days of sub-1G memory systems with heavy use of swap are over. If we ever need thrashing reducing code in the future, we will have to implement something that does scale. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Hugh Dickins <hughd@google.com> Acked-by: Bob Picco <bpicco@meloft.net> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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904249aa |
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25-Apr-2012 |
Ying Han <yinghan@google.com> |
mm: fix up the vmscan stat in vmstat The "pgsteal" stat is confusing because it counts both direct reclaim as well as background reclaim. However, we have "kswapd_steal" which also counts background reclaim value. This patch fixes it and also makes it match the existng "pgscan_" stats. Test: pgsteal_kswapd_dma32 447623 pgsteal_kswapd_normal 42272677 pgsteal_kswapd_movable 0 pgsteal_direct_dma32 2801 pgsteal_direct_normal 44353270 pgsteal_direct_movable 0 Signed-off-by: Ying Han <yinghan@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mel@csn.ul.ie> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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41c93088 |
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12-Apr-2012 |
Ying Han <yinghan@google.com> |
Revert "mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()" This reverts commit c38446cc65e1f2b3eb8630c53943b94c4f65f670. Before the commit, the code makes senses to me but not after the commit. The "nr_reclaimed" is the number of pages reclaimed by scanning through the memcg's lru lists. The "nr_to_reclaim" is the target value for the whole function. For example, we like to early break the reclaim if reclaimed 32 pages under direct reclaim (not DEF_PRIORITY). After the reverted commit, the target "nr_to_reclaim" is decremented each time by "nr_reclaimed" but we still use it to compare the "nr_reclaimed". It just doesn't make sense to me... Signed-off-by: Ying Han <yinghan@google.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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496b919b |
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24-Mar-2012 |
Rik van Riel <riel@redhat.com> |
Fix potential endless loop in kswapd when compaction is not enabled We should only test compaction_suitable if the kernel is built with CONFIG_COMPACTION, otherwise the stub compaction_suitable function will always return COMPACT_SKIPPED and send kswapd into an infinite loop. Reported-by: Anton Blanchard <anton@samba.org> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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643ac9fc |
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23-Mar-2012 |
Hugh Dickins <hughd@google.com> |
mm: fix testorder interaction between two kswapd patches Adjusting cc715d99e529 "mm: vmscan: forcibly scan highmem if there are too many buffer_heads pinning highmem" for -stable reveals that it was slightly wrong once on top of fe2c2a106663 "vmscan: reclaim at order 0 when compaction is enabled", which specifically adds testorder for the zone_watermark_ok_safe() test. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1480de03 |
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21-Mar-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm: forbid lumpy-reclaim in shrink_active_list() Reset the reclaim mode in shrink_active_list() to RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC. (sync/async sign is used only in shrink_page_list and does not affect shrink_active_list) Currenly shrink_active_list() sometimes works in lumpy-reclaim mode, if RECLAIM_MODE_LUMPYRECLAIM is left over from an earlier shrink_inactive_list(). Meanwhile, in age_active_anon() sc->reclaim_mode is totally zero. So the current behavior is too complex and confusing, and this looks like bug. In general, shrink_active_list() populates the inactive list for the next shrink_inactive_list(). Lumpy shring_inactive_list() isolates pages around the chosen one from both the active and inactive lists. So, there is no reason for lumpy isolation in shrink_active_list(). See also: https://lkml.org/lkml/2012/3/15/583 Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Proposed-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cc9a6c87 |
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21-Mar-2012 |
Mel Gorman <mgorman@suse.de> |
cpuset: mm: reduce large amounts of memory barrier related damage v3 Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when changing cpuset's mems") wins a super prize for the largest number of memory barriers entered into fast paths for one commit. [get|put]_mems_allowed is incredibly heavy with pairs of full memory barriers inserted into a number of hot paths. This was detected while investigating at large page allocator slowdown introduced some time after 2.6.32. The largest portion of this overhead was shown by oprofile to be at an mfence introduced by this commit into the page allocator hot path. For extra style points, the commit introduced the use of yield() in an implementation of what looks like a spinning mutex. This patch replaces the full memory barriers on both read and write sides with a sequence counter with just read barriers on the fast path side. This is much cheaper on some architectures, including x86. The main bulk of the patch is the retry logic if the nodemask changes in a manner that can cause a false failure. While updating the nodemask, a check is made to see if a false failure is a risk. If it is, the sequence number gets bumped and parallel allocators will briefly stall while the nodemask update takes place. In a page fault test microbenchmark, oprofile samples from __alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The actual results were 3.3.0-rc3 3.3.0-rc3 rc3-vanilla nobarrier-v2r1 Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%) Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%) Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%) Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%) Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%) Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%) Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%) Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%) Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%) Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%) Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%) Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%) Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%) Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%) Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%) MMTests Statistics: duration Sys Time Running Test (seconds) 135.68 132.17 User+Sys Time Running Test (seconds) 164.2 160.13 Total Elapsed Time (seconds) 123.46 120.87 The overall improvement is small but the System CPU time is much improved and roughly in correlation to what oprofile reported (these performance figures are without profiling so skew is expected). The actual number of page faults is noticeably improved. For benchmarks like kernel builds, the overall benefit is marginal but the system CPU time is slightly reduced. To test the actual bug the commit fixed I opened two terminals. The first ran within a cpuset and continually ran a small program that faulted 100M of anonymous data. In a second window, the nodemask of the cpuset was continually randomised in a loop. Without the commit, the program would fail every so often (usually within 10 seconds) and obviously with the commit everything worked fine. With this patch applied, it also worked fine so the fix should be functionally equivalent. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c7cfa37b |
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21-Mar-2012 |
Copot Alexandru <alex.mihai.c@gmail.com> |
mm/vmscan.c: fix spelling error s/noticable/noticeable/ Signed-off-by: Copot Alexandru <alex.mihai.c@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d563c050 |
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21-Mar-2012 |
Hillf Danton <dhillf@gmail.com> |
vmscan: handle isolated pages with lru lock released When shrinking inactive lru list, isolated pages are queued on locally private list, so the lock-hold time could be reduced if pages are counted without lock protection. To achieve that, firstly updating reclaim stat is delayed until the putback stage, after reacquiring the lru lock. Secondly, operations related to vm and zone stats are now proteced with preemption disabled as they are per-cpu operations. Signed-off-by: Hillf Danton <dhillf@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cc715d99 |
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21-Mar-2012 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: forcibly scan highmem if there are too many buffer_heads pinning highmem Stuart Foster reported on bugzilla that copying large amounts of data from NTFS caused an OOM kill on 32-bit X86 with 16G of memory. Andrew Morton correctly identified that the problem was NTFS was using 512 blocks meaning each page had 8 buffer_heads in low memory pinning it. In the past, direct reclaim used to scan highmem even if the allocating process did not specify __GFP_HIGHMEM but not any more. kswapd no longer will reclaim from zones that are above the high watermark. The intention in both cases was to minimise unnecessary reclaim. The downside is on machines with large amounts of highmem that lowmem can be fully consumed by buffer_heads with nothing trying to free them. The following patch is based on a suggestion by Andrew Morton to extend the buffer_heads_over_limit case to force kswapd and direct reclaim to scan the highmem zone regardless of the allocation request or watermarks. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=42578 [hughd@google.com: move buffer_heads_over_limit check up] [akpm@linux-foundation.org: buffer_heads_over_limit is unlikely] Reported-by: Stuart Foster <smf.linux@ntlworld.com> Tested-by: Stuart Foster <smf.linux@ntlworld.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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aff62249 |
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21-Mar-2012 |
Rik van Riel <riel@redhat.com> |
vmscan: only defer compaction for failed order and higher Currently a failed order-9 (transparent hugepage) compaction can lead to memory compaction being temporarily disabled for a memory zone. Even if we only need compaction for an order 2 allocation, eg. for jumbo frames networking. The fix is relatively straightforward: keep track of the highest order at which compaction is succeeding, and only defer compaction for orders at which compaction is failing. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7be62de9 |
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21-Mar-2012 |
Rik van Riel <riel@redhat.com> |
vmscan: kswapd carefully call compaction With CONFIG_COMPACTION enabled, kswapd does not try to free contiguous free pages, even when it is woken for a higher order request. This could be bad for eg. jumbo frame network allocations, which are done from interrupt context and cannot compact memory themselves. Higher than before allocation failure rates in the network receive path have been observed in kernels with compaction enabled. Teach kswapd to defragment the memory zones in a node, but only if required and compaction is not deferred in a zone. [akpm@linux-foundation.org: reduce scope of zones_need_compaction] Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fe2c2a10 |
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21-Mar-2012 |
Rik van Riel <riel@redhat.com> |
vmscan: reclaim at order 0 when compaction is enabled When built with CONFIG_COMPACTION, kswapd should not try to free contiguous pages, because it is not trying hard enough to have a real chance at being successful, but still disrupts the LRU enough to break other things. Do not do higher order page isolation unless we really are in lumpy reclaim mode. Stop reclaiming pages once we have enough free pages that compaction can deal with things, and we hit the normal order 0 watermarks used by kswapd. Also remove a line of code that increments balanced right before exiting the function. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c38446cc |
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21-Mar-2012 |
Hillf Danton <dhillf@gmail.com> |
mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone() The value of nr_reclaimed is the number of pages reclaimed in the current round of the loop, whereas nr_to_reclaim should be compared with the number of pages reclaimed in all rounds. In each round of the loop, reclaimed pages are cut off from the reclaim goal, and the loop stops once the goal achieved. Signed-off-by: Hillf Danton <dhillf@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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61317289 |
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21-Mar-2012 |
Hillf Danton <dhillf@gmail.com> |
mm/vmscan.c: cleanup with s/reclaim_mode/isolate_mode/ With tons of reclaim_mode (defined as one field of struct scan_control) already in the file, it is clearer to rename the local reclaim_mode when setting up the isolation mode. Signed-off-by: Hillf Danton <dhillf@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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24513264 |
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20-Jan-2012 |
Hugh Dickins <hughd@google.com> |
SHM_UNLOCK: fix Unevictable pages stranded after swap Commit cc39c6a9bbde ("mm: account skipped entries to avoid looping in find_get_pages") correctly fixed an infinite loop; but left a problem that find_get_pages() on shmem would return 0 (appearing to callers to mean end of tree) when it meets a run of nr_pages swap entries. The only uses of find_get_pages() on shmem are via pagevec_lookup(), called from invalidate_mapping_pages(), and from shmctl SHM_UNLOCK's scan_mapping_unevictable_pages(). The first is already commented, and not worth worrying about; but the second can leave pages on the Unevictable list after an unusual sequence of swapping and locking. Fix that by using shmem_find_get_pages_and_swap() (then ignoring the swap) instead of pagevec_lookup(). But I don't want to contaminate vmscan.c with shmem internals, nor shmem.c with LRU locking. So move scan_mapping_unevictable_pages() into shmem.c, renaming it shmem_unlock_mapping(); and rename check_move_unevictable_page() to check_move_unevictable_pages(), looping down an array of pages, oftentimes under the same lock. Leave out the "rotate unevictable list" block: that's a leftover from when this was used for /proc/sys/vm/scan_unevictable_pages, whose flawed handling involved looking at pages at tail of LRU. Was there significance to the sequence first ClearPageUnevictable, then test page_evictable, then SetPageUnevictable here? I think not, we're under LRU lock, and have no barriers between those. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: <stable@vger.kernel.org> [back to 3.1 but will need respins] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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85046579 |
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20-Jan-2012 |
Hugh Dickins <hughd@google.com> |
SHM_UNLOCK: fix long unpreemptible section scan_mapping_unevictable_pages() is used to make SysV SHM_LOCKed pages evictable again once the shared memory is unlocked. It does this with pagevec_lookup()s across the whole object (which might occupy most of memory), and takes 300ms to unlock 7GB here. A cond_resched() every PAGEVEC_SIZE pages would be good. However, KOSAKI-san points out that this is called under shmem.c's info->lock, and it's also under shm.c's shm_lock(), both spinlocks. There is no strong reason for that: we need to take these pages off the unevictable list soonish, but those locks are not required for it. So move the call to scan_mapping_unevictable_pages() from shmem.c's unlock handling up to shm.c's unlock handling. Remove the recently added barrier, not needed now we have spin_unlock() before the scan. Use get_file(), with subsequent fput(), to make sure we have a reference to mapping throughout scan_mapping_unevictable_pages(): that's something that was previously guaranteed by the shm_lock(). Remove shmctl's lru_add_drain_all(): we don't fault in pages at SHM_LOCK time, and we lazily discover them to be Unevictable later, so it serves no purpose for SHM_LOCK; and serves no purpose for SHM_UNLOCK, since pages still on pagevec are not marked Unevictable. The original code avoided redundant rescans by checking VM_LOCKED flag at its level: now avoid them by checking shp's SHM_LOCKED. The original code called scan_mapping_unevictable_pages() on a locked area at shm_destroy() time: perhaps we once had accounting cross-checks which required that, but not now, so skip the overhead and just let inode eviction deal with them. Put check_move_unevictable_page() and scan_mapping_unevictable_pages() under CONFIG_SHMEM (with stub for the TINY case when ramfs is used), more as comment than to save space; comment them used for SHM_UNLOCK. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3f79768f |
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12-Jan-2012 |
Hugh Dickins <hughd@google.com> |
mm: rearrange putback_inactive_pages There is sometimes confusion between the global putback_lru_pages() in migrate.c and the static putback_lru_pages() in vmscan.c: rename the latter putback_inactive_pages(): it helps shrink_inactive_list() rather as move_active_pages_to_lru() helps shrink_active_list(). Remove unused scan_control arg from putback_inactive_pages() and from update_isolated_counts(). Move clear_active_flags() inside update_isolated_counts(). Move NR_ISOLATED accounting up into shrink_inactive_list() itself, so the balance is clearer. Do the spin_lock_irq() before calling putback_inactive_pages() and spin_unlock_irq() after return from it, so that it better matches update_isolated_counts() and move_active_pages_to_lru(). Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f626012d |
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12-Jan-2012 |
Hugh Dickins <hughd@google.com> |
mm: remove isolate_pages() The isolate_pages() level in vmscan.c offers little but indirection: merge it into isolate_lru_pages() as the compiler does, and use the names nr_to_scan and nr_scanned in each case. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4111304d |
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12-Jan-2012 |
Hugh Dickins <hughd@google.com> |
mm: enum lru_list lru Mostly we use "enum lru_list lru": change those few "l"s to "lru"s. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2bcf8879 |
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12-Jan-2012 |
Hugh Dickins <hughd@google.com> |
mm: take pagevecs off reclaim stack Replace pagevecs in putback_lru_pages() and move_active_pages_to_lru() by lists of pages_to_free: then apply Konstantin Khlebnikov's free_hot_cold_page_list() to them instead of pagevec_release(). Which simplifies the flow (no need to drop and retake lock whenever pagevec fills up) and reduces stale addresses in stack backtraces (which often showed through the pagevecs); but more importantly, removes another 120 bytes from the deepest stacks in page reclaim. Although I've not recently seen an actual stack overflow here with a vanilla kernel, move_active_pages_to_lru() has often featured in deep backtraces. However, free_hot_cold_page_list() does not handle compound pages (nor need it: a Transparent HugePage would have been split by the time it reaches the call in shrink_page_list()), but it is possible for putback_lru_pages() or move_active_pages_to_lru() to be left holding the last reference on a THP, so must exclude the unlikely compound case before putting on pages_to_free. Remove pagevec_strip(), its work now done in move_active_pages_to_lru(). The pagevec in scan_mapping_unevictable_pages() remains in mm/vmscan.c, but that is never on the reclaim path, and cannot be replaced by a list. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0cee34fd |
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12-Jan-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: check if reclaim should really abort even if compaction_ready() is true for one zone If compaction can proceed for a given zone, shrink_zones() does not reclaim any more pages from it. After commit [e0c2327: vmscan: abort reclaim/compaction if compaction can proceed], do_try_to_free_pages() tries to finish as soon as possible once one zone can compact. This was intended to prevent slabs being shrunk unnecessarily but there are side-effects. One is that a small zone that is ready for compaction will abort reclaim even if the chances of successfully allocating a THP from that zone is small. It also means that reclaim can return too early even though sc->nr_to_reclaim pages were not reclaimed. This partially reverts the commit until it is proven that slabs are really being shrunk unnecessarily but preserves the check to return 1 to avoid OOM if reclaim was aborted prematurely. [aarcange@redhat.com: This patch replaces a revert from Andrea] Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fe4b1b24 |
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12-Jan-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: when reclaiming for compaction, ensure there are sufficient free pages available In commit e0887c19 ("vmscan: limit direct reclaim for higher order allocations"), Rik noted that reclaim was too aggressive when THP was enabled. In his initial patch he used the number of free pages to decide if reclaim should abort for compaction. My feedback was that reclaim and compaction should be using the same logic when deciding if reclaim should be aborted. Unfortunately, this had the effect of reducing THP success rates when the workload included something like streaming reads that continually allocated pages. The window during which compaction could run and return a THP was too small. This patch combines Rik's two patches together. compaction_suitable() is still used to decide if reclaim should be aborted to allow compaction is used. However, it will also ensure that there is a reasonable buffer of free pages available. This improves upon the THP allocation success rates but bounds the number of pages that are freed for compaction. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel<riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c8244935 |
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12-Jan-2012 |
Mel Gorman <mgorman@suse.de> |
mm: compaction: make isolate_lru_page() filter-aware again Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware") noted that compaction does not migrate dirty or writeback pages and that is was meaningless to pick the page and re-add it to the LRU list. This had to be partially reverted because some dirty pages can be migrated by compaction without blocking. This patch updates "mm: compaction: make isolate_lru_page" by skipping over pages that migration has no possibility of migrating to minimise LRU disruption. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel<riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7335084d |
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12-Jan-2012 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not OOM if aborting reclaim to start compaction During direct reclaim it is possible that reclaim will be aborted so that compaction can be attempted to satisfy a high-order allocation. If this decision is made before any pages are reclaimed, it is possible that 0 is returned to the page allocator potentially triggering an OOM. This has not been observed but it is a possibility so this patch addresses it. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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50134731 |
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12-Jan-2012 |
Andrea Arcangeli <aarcange@redhat.com> |
mm: vmscan: check if we isolated a compound page during lumpy scan Properly take into account if we isolated a compound page during the lumpy scan in reclaim and skip over the tail pages when encountered. This corrects the values given to the tracepoint for number of lumpy pages isolated and will avoid breaking the loop early if compound pages smaller than the requested allocation size are requested. [mgorman@suse.de: Updated changelog] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ea4d349f |
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12-Jan-2012 |
Tao Ma <boyu.mt@taobao.com> |
vmscan/trace: Add 'file' info to trace_mm_vmscan_lru_isolate() In trace_mm_vmscan_lru_isolate(), we don't output 'file' information to the trace event and it is a bit inconvenient for the user to get the real information(like pasted below). mm_vmscan_lru_isolate: isolate_mode=2 order=0 nr_requested=32 nr_scanned=32 nr_taken=32 contig_taken=0 contig_dirty=0 contig_failed=0 'active' can be obtained by analyzing mode(Thanks go to Minchan and Mel), So this patch adds 'file' to the trace event and it now looks like: mm_vmscan_lru_isolate: isolate_mode=2 order=0 nr_requested=32 nr_scanned=32 nr_taken=32 contig_taken=0 contig_dirty=0 contig_failed=0 file=0 Signed-off-by: Tao Ma <boyu.mt@taobao.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
72835c86 |
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12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: unify remaining mem_cont, mem, etc. variable names to memcg Signed-off-by: Johannes Weiner <jweiner@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
925b7673 |
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12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: make per-memcg LRU lists exclusive Now that all code that operated on global per-zone LRU lists is converted to operate on per-memory cgroup LRU lists instead, there is no reason to keep the double-LRU scheme around any longer. The pc->lru member is removed and page->lru is linked directly to the per-memory cgroup LRU lists, which removes two pointers from a descriptor that exists for every page frame in the system. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Ying Han <yinghan@google.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
6290df54 |
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12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: collect LRU list heads into struct lruvec Having a unified structure with a LRU list set for both global zones and per-memcg zones allows to keep that code simple which deals with LRU lists and does not care about the container itself. Once the per-memcg LRU lists directly link struct pages, the isolation function and all other list manipulations are shared between the memcg case and the global LRU case. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b95a2f2d |
|
12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: vmscan: convert global reclaim to per-memcg LRU lists The global per-zone LRU lists are about to go away on memcg-enabled kernels, global reclaim must be able to find its pages on the per-memcg LRU lists. Since the LRU pages of a zone are distributed over all existing memory cgroups, a scan target for a zone is complete when all memory cgroups are scanned for their proportional share of a zone's memory. The forced scanning of small scan targets from kswapd is limited to zones marked unreclaimable, otherwise kswapd can quickly overreclaim by force-scanning the LRU lists of multiple memory cgroups. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
5660048c |
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12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: move memcg hierarchy reclaim to generic reclaim code Memory cgroup limit reclaim and traditional global pressure reclaim will soon share the same code to reclaim from a hierarchical tree of memory cgroups. In preparation of this, move the two right next to each other in shrink_zone(). The mem_cgroup_hierarchical_reclaim() polymath is split into a soft limit reclaim function, which still does hierarchy walking on its own, and a limit (shrinking) reclaim function, which relies on generic reclaim code to walk the hierarchy. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f16015fb |
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12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: vmscan: distinguish between memcg triggering reclaim and memcg being scanned Memory cgroup hierarchies are currently handled completely outside of the traditional reclaim code, which is invoked with a single memory cgroup as an argument for the whole call stack. Subsequent patches will switch this code to do hierarchical reclaim, so there needs to be a distinction between a) the memory cgroup that is triggering reclaim due to hitting its limit and b) the memory cgroup that is being scanned as a child of a). This patch introduces a struct mem_cgroup_zone that contains the combination of the memory cgroup and the zone being scanned, which is then passed down the stack instead of the zone argument. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
89b5fae5 |
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12-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: vmscan: distinguish global reclaim from global LRU scanning The traditional zone reclaim code is scanning the per-zone LRU lists during direct reclaim and kswapd, and the per-zone per-memory cgroup LRU lists when reclaiming on behalf of a memory cgroup limit. Subsequent patches will convert the traditional reclaim code to reclaim exclusively from the per-memory cgroup LRU lists. As a result, using the predicate for which LRU list is scanned will no longer be appropriate to tell global reclaim from limit reclaim. This patch adds a global_reclaim() predicate to tell direct/kswapd reclaim from memory cgroup limit reclaim and substitutes it in all places where currently scanning_global_lru() is used for that. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3770490e |
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10-Jan-2012 |
Hillf Danton <dhillf@gmail.com> |
mm: vmscan: fix typo in isolating lru pages It is not the tag page but the cursor page that we should process, and it looks a typo. Signed-off-by: Hillf Danton <dhillf@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
043bcbe5 |
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10-Jan-2012 |
Hugh Dickins <hughd@google.com> |
mm: test PageSwapBacked in lumpy reclaim Lumpy reclaim does well to stop at a PageAnon when there's no swap, but better is to stop at any PageSwapBacked, which includes shmem/tmpfs too. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
86cfd3a4 |
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10-Jan-2012 |
Minchan Kim <minchan@kernel.org> |
mm/vmscan.c: consider swap space when deciding whether to continue reclaim It's pointless to continue reclaiming when we have no swap space and lots of anon pages in the inactive list. Without this patch, it is possible when swap is disabled to continue trying to reclaim when there are only anonymous pages in the system even though that will not make any progress. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
25bd91bd |
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10-Jan-2012 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: add task name to warn_scan_unevictable() messages If we need to know a usecase, caller program name is critical important. Show it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> David Rientjes <rientjes@google.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
cc59850e |
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10-Jan-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm: add free_hot_cold_page_list() helper This patch adds helper free_hot_cold_page_list() to free list of 0-order pages. It frees pages directly from list without temporary page-vector. It also calls trace_mm_pagevec_free() to simulate pagevec_free() behaviour. bloat-o-meter: add/remove: 1/1 grow/shrink: 1/3 up/down: 267/-295 (-28) function old new delta free_hot_cold_page_list - 264 +264 get_page_from_freelist 2129 2132 +3 __pagevec_free 243 239 -4 split_free_page 380 373 -7 release_pages 606 510 -96 free_page_list 188 - -188 Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c909e993 |
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10-Jan-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
vmscan: activate executable pages after first usage Logic added in commit 8cab4754d24a0 ("vmscan: make mapped executable pages the first class citizen") was noticeably weakened in commit 645747462435d84 ("vmscan: detect mapped file pages used only once"). Currently these pages can become "first class citizens" only after second usage. After this patch page_check_references() will activate they after first usage, and executable code gets yet better chance to stay in memory. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
34dbc67a |
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10-Jan-2012 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
vmscan: promote shared file mapped pages Commit 645747462435 ("vmscan: detect mapped file pages used only once") greatly decreases lifetime of single-used mapped file pages. Unfortunately it also decreases life time of all shared mapped file pages. Because after commit bf3f3bc5e7347 ("mm: don't mark_page_accessed in fault path") page-fault handler does not mark page active or even referenced. Thus page_check_references() activates file page only if it was used twice while it stays in inactive list, meanwhile it activates anon pages after first access. Inactive list can be small enough, this way reclaimer can accidentally throw away any widely used page if it wasn't used twice in short period. After this patch page_check_references() also activate file mapped page at first inactive list scan if this page is already used multiple times via several ptes. I found this while trying to fix degragation in rhel6 (~2.6.32) from rhel5 (~2.6.18). There a complete mess with >100 web/mail/spam/ftp containers, they share all their files but there a lot of anonymous pages: ~500mb shared file mapped memory and 15-20Gb non-shared anonymous memory. In this situation major-pagefaults are very costly, because all containers share the same page. In my load kernel created a disproportionate pressure on the file memory, compared with the anonymous, they equaled only if I raise swappiness up to 150 =) These patches actually wasn't helped a lot in my problem, but I saw noticable (10-20 times) reduce in count and average time of major-pagefault in file-mapped areas. Actually both patches are fixes for commit v2.6.33-5448-g6457474, because it was aimed at one scenario (singly used pages), but it breaks the logic in other scenarios (shared and/or executable pages) Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
10fbcf4c |
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21-Dec-2011 |
Kay Sievers <kay.sievers@vrfy.org> |
convert 'memory' sysdev_class to a regular subsystem This moves the 'memory sysdev_class' over to a regular 'memory' subsystem and converts the devices to regular devices. The sysdev drivers are implemented as subsystem interfaces now. After all sysdev classes are ported to regular driver core entities, the sysdev implementation will be entirely removed from the kernel. Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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#
83aeeada |
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08-Dec-2011 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
vmscan: use atomic-long for shrinker batching Use atomic-long operations instead of looping around cmpxchg(). [akpm@linux-foundation.org: massage atomic.h inclusions] Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
635697c6 |
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08-Dec-2011 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
vmscan: fix initial shrinker size handling A shrinker function can return -1, means that it cannot do anything without a risk of deadlock. For example prune_super() does this if it cannot grab a superblock refrence, even if nr_to_scan=0. Currently we interpret this -1 as a ULONG_MAX size shrinker and evaluate `total_scan' according to this. So the next time around this shrinker can cause really big pressure. Let's skip such shrinkers instead. Also make total_scan signed, otherwise the check (total_scan < 0) below never works. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9b272977 |
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02-Nov-2011 |
Johannes Weiner <jweiner@redhat.com> |
memcg: skip scanning active lists based on individual size Reclaim decides to skip scanning an active list when the corresponding inactive list is above a certain size in comparison to leave the assumed working set alone while there are still enough reclaim candidates around. The memcg implementation of comparing those lists instead reports whether the whole memcg is low on the requested type of inactive pages, considering all nodes and zones. This can lead to an oversized active list not being scanned because of the state of the other lists in the memcg, as well as an active list being scanned while its corresponding inactive list has enough pages. Not only is this wrong, it's also a scalability hazard, because the global memory state over all nodes and zones has to be gathered for each memcg and zone scanned. Make these calculations purely based on the size of the two LRU lists that are actually affected by the outcome of the decision. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e0c23279 |
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31-Oct-2011 |
Mel Gorman <mgorman@suse.de> |
vmscan: abort reclaim/compaction if compaction can proceed If compaction can proceed, shrink_zones() stops doing any work but its callers still call shrink_slab() which raises the priority and potentially sleeps. This is unnecessary and wasteful so this patch aborts direct reclaim/compaction entirely if compaction can proceed. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e0887c19 |
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31-Oct-2011 |
Rik van Riel <riel@redhat.com> |
vmscan: limit direct reclaim for higher order allocations When suffering from memory fragmentation due to unfreeable pages, THP page faults will repeatedly try to compact memory. Due to the unfreeable pages, compaction fails. Needless to say, at that point page reclaim also fails to create free contiguous 2MB areas. However, that doesn't stop the current code from trying, over and over again, and freeing a minimum of 4MB (2UL << sc->order pages) at every single invocation. This resulted in my 12GB system having 2-3GB free memory, a corresponding amount of used swap and very sluggish response times. This can be avoided by having the direct reclaim code not reclaim from zones that already have plenty of free memory available for compaction. If compaction still fails due to unmovable memory, doing additional reclaim will only hurt the system, not help. [jweiner@redhat.com: change comment to explain the order check] Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
21ee9f39 |
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31-Oct-2011 |
Minchan Kim <minchan.kim@gmail.com> |
vmscan: add barrier to prevent evictable page in unevictable list When a race between putback_lru_page() and shmem_lock with lock=0 happens, progrom execution order is as follows, but clear_bit in processor #1 could be reordered right before spin_unlock of processor #1. Then, the page would be stranded on the unevictable list. spin_lock SetPageLRU spin_unlock clear_bit(AS_UNEVICTABLE) spin_lock if PageLRU() if !test_bit(AS_UNEVICTABLE) move evictable list smp_mb if !test_bit(AS_UNEVICTABLE) move evictable list spin_unlock But, pagevec_lookup() in scan_mapping_unevictable_pages() has rcu_read_[un]lock() so it could protect reordering before reaching test_bit(AS_UNEVICTABLE) on processor #1 so this problem never happens. But it's a unexpected side effect and we should solve this problem properly. This patch adds a barrier after mapping_clear_unevictable. I didn't meet this problem but just found during review. Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
264e56d8 |
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31-Oct-2011 |
Johannes Weiner <jweiner@redhat.com> |
mm: disable user interface to manually rescue unevictable pages At one point, anonymous pages were supposed to go on the unevictable list when no swap space was configured, and the idea was to manually rescue those pages after adding swap and making them evictable again. But nowadays, swap-backed pages on the anon LRU list are not scanned without available swap space anyway, so there is no point in moving them to a separate list anymore. The manual rescue could also be used in case pages were stranded on the unevictable list due to race conditions. But the code has been around for a while now and newly discovered bugs should be properly reported and dealt with instead of relying on such a manual fixup. In addition to the lack of a usecase, the sysfs interface to rescue pages from a specific NUMA node has been broken since its introduction, so it's unlikely that anybody ever relied on that. This patch removes the functionality behind the sysctl and the node-interface and emits a one-time warning when somebody tries to access either of them. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reported-by: Kautuk Consul <consul.kautuk@gmail.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3f380998 |
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31-Oct-2011 |
Kautuk Consul <consul.kautuk@gmail.com> |
vmscan.c: fix invalid strict_strtoul() check in write_scan_unevictable_node() write_scan_unevictable_node() checks the value req returned by strict_strtoul() and returns 1 if req is 0. However, when strict_strtoul() returns 0, it means successful conversion of buf to unsigned long. Due to this, the function was not proceeding to scan the zones for unevictable pages even though we write a valid value to the scan_unevictable_pages sys file. Change this check slightly to check for invalid value in buf as well as 0 value stored in res after successful conversion via strict_strtoul. In both cases, we do not perform the scanning of this node's zones. Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f0dfcde0 |
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31-Oct-2011 |
Alex Shi <alex.shi@linux.alibaba.com> |
kswapd: assign new_order and new_classzone_idx after wakeup in sleeping There 2 places to read pgdat in kswapd. One is return from a successful balance, another is waked up from kswapd sleeping. The new_order and new_classzone_idx represent the balance input order and classzone_idx. But current new_order and new_classzone_idx are not assigned after kswapd_try_to_sleep(), that will cause a bug in the following scenario. 1: after a successful balance, kswapd goes to sleep, and new_order = 0; new_classzone_idx = __MAX_NR_ZONES - 1; 2: kswapd waked up with order = 3 and classzone_idx = ZONE_NORMAL 3: in the balance_pgdat() running, a new balance wakeup happened with order = 5, and classzone_idx = ZONE_NORMAL 4: the first wakeup(order = 3) finished successufly, return order = 3 but, the new_order is still 0, so, this balancing will be treated as a failed balance. And then the second tighter balancing will be missed. So, to avoid the above problem, the new_order and new_classzone_idx need to be assigned for later successful comparison. Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Tested-by: Pádraig Brady <P@draigBrady.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d2ebd0f6 |
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31-Oct-2011 |
Alex Shi <alex.shi@linux.alibaba.com> |
kswapd: avoid unnecessary rebalance after an unsuccessful balancing In commit 215ddd66 ("mm: vmscan: only read new_classzone_idx from pgdat when reclaiming successfully") , Mel Gorman said kswapd is better to sleep after a unsuccessful balancing if there is tighter reclaim request pending in the balancing. But in the following scenario, kswapd do something that is not matched our expectation. The patch fixes this issue. 1, Read pgdat request A (classzone_idx, order = 3) 2, balance_pgdat() 3, During pgdat, a new pgdat request B (classzone_idx, order = 5) is placed 4, balance_pgdat() returns but failed since returned order = 0 5, pgdat of request A assigned to balance_pgdat(), and do balancing again. While the expectation behavior of kswapd should try to sleep. Signed-off-by: Alex Shi <alex.shi@intel.com> Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Tested-by: Pádraig Brady <P@draigBrady.com> Cc: Rik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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16fb9512 |
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31-Oct-2011 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: count pages into balanced for zone with good watermark It's possible a zone watermark is ok when entering the balance_pgdat() loop, while the zone is within the requested classzone_idx. Count pages from this zone into `balanced'. In this way, we can skip shrinking zones too much for high order allocation. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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49ea7eb6 |
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31-Oct-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: immediately reclaim end-of-LRU dirty pages when writeback completes When direct reclaim encounters a dirty page, it gets recycled around the LRU for another cycle. This patch marks the page PageReclaim similar to deactivate_page() so that the page gets reclaimed almost immediately after the page gets cleaned. This is to avoid reclaiming clean pages that are younger than a dirty page encountered at the end of the LRU that might have been something like a use-once page. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <jweiner@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Alex Elder <aelder@sgi.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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92df3a72 |
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31-Oct-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: throttle reclaim if encountering too many dirty pages under writeback Workloads that are allocating frequently and writing files place a large number of dirty pages on the LRU. With use-once logic, it is possible for them to reach the end of the LRU quickly requiring the reclaimer to scan more to find clean pages. Ordinarily, processes that are dirtying memory will get throttled by dirty balancing but this is a global heuristic and does not take into account that LRUs are maintained on a per-zone basis. This can lead to a situation whereby reclaim is scanning heavily, skipping over a large number of pages under writeback and recycling them around the LRU consuming CPU. This patch checks how many of the number of pages isolated from the LRU were dirty and under writeback. If a percentage of them under writeback, the process will be throttled if a backing device or the zone is congested. Note that this applies whether it is anonymous or file-backed pages that are under writeback meaning that swapping is potentially throttled. This is intentional due to the fact if the swap device is congested, scanning more pages and dispatching more IO is not going to help matters. The percentage that must be in writeback depends on the priority. At default priority, all of them must be dirty. At DEF_PRIORITY-1, 50% of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases the greater the likelihood the process will get throttled to allow the flusher threads to make some progress. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Alex Elder <aelder@sgi.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f84f6e2b |
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31-Oct-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not writeback filesystem pages in kswapd except in high priority It is preferable that no dirty pages are dispatched for cleaning from the page reclaim path. At normal priorities, this patch prevents kswapd writing pages. However, page reclaim does have a requirement that pages be freed in a particular zone. If it is failing to make sufficient progress (reclaiming < SWAP_CLUSTER_MAX at any priority priority), the priority is raised to scan more pages. A priority of DEF_PRIORITY - 3 is considered to be the point where kswapd is getting into trouble reclaiming pages. If this priority is reached, kswapd will dispatch pages for writing. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Alex Elder <aelder@sgi.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a18bba06 |
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31-Oct-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: remove dead code related to lumpy reclaim waiting on pages under writeback Lumpy reclaim worked with two passes - the first which queued pages for IO and the second which waited on writeback. As direct reclaim can no longer write pages there is some dead code. This patch removes it but direct reclaim will continue to wait on pages under writeback while in synchronous reclaim mode. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Alex Elder <aelder@sgi.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ee72886d |
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31-Oct-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: do not writeback filesystem pages in direct reclaim Testing from the XFS folk revealed that there is still too much I/O from the end of the LRU in kswapd. Previously it was considered acceptable by VM people for a small number of pages to be written back from reclaim with testing generally showing about 0.3% of pages reclaimed were written back (higher if memory was low). That writing back a small number of pages is ok has been heavily disputed for quite some time and Dave Chinner explained it well; It doesn't have to be a very high number to be a problem. IO is orders of magnitude slower than the CPU time it takes to flush a page, so the cost of making a bad flush decision is very high. And single page writeback from the LRU is almost always a bad flush decision. To complicate matters, filesystems respond very differently to requests from reclaim according to Christoph Hellwig; xfs tries to write it back if the requester is kswapd ext4 ignores the request if it's a delayed allocation btrfs ignores the request As a result, each filesystem has different performance characteristics when under memory pressure and there are many pages being dirtied. In some cases, the request is ignored entirely so the VM cannot depend on the IO being dispatched. The objective of this series is to reduce writing of filesystem-backed pages from reclaim, play nicely with writeback that is already in progress and throttle reclaim appropriately when writeback pages are encountered. The assumption is that the flushers will always write pages faster than if reclaim issues the IO. A secondary goal is to avoid the problem whereby direct reclaim splices two potentially deep call stacks together. There is a potential new problem as reclaim has less control over how long before a page in a particularly zone or container is cleaned and direct reclaimers depend on kswapd or flusher threads to do the necessary work. However, as filesystems sometimes ignore direct reclaim requests already, it is not expected to be a serious issue. Patch 1 disables writeback of filesystem pages from direct reclaim entirely. Anonymous pages are still written. Patch 2 removes dead code in lumpy reclaim as it is no longer able to synchronously write pages. This hurts lumpy reclaim but there is an expectation that compaction is used for hugepage allocations these days and lumpy reclaim's days are numbered. Patches 3-4 add warnings to XFS and ext4 if called from direct reclaim. With patch 1, this "never happens" and is intended to catch regressions in this logic in the future. Patch 5 disables writeback of filesystem pages from kswapd unless the priority is raised to the point where kswapd is considered to be in trouble. Patch 6 throttles reclaimers if too many dirty pages are being encountered and the zones or backing devices are congested. Patch 7 invalidates dirty pages found at the end of the LRU so they are reclaimed quickly after being written back rather than waiting for a reclaimer to find them I consider this series to be orthogonal to the writeback work but it is worth noting that the writeback work affects the viability of patch 8 in particular. I tested this on ext4 and xfs using fs_mark, a simple writeback test based on dd and a micro benchmark that does a streaming write to a large mapping (exercises use-once LRU logic) followed by streaming writes to a mix of anonymous and file-backed mappings. The command line for fs_mark when botted with 512M looked something like ./fs_mark -d /tmp/fsmark-2676 -D 100 -N 150 -n 150 -L 25 -t 1 -S0 -s 10485760 The number of files was adjusted depending on the amount of available memory so that the files created was about 3xRAM. For multiple threads, the -d switch is specified multiple times. The test machine is x86-64 with an older generation of AMD processor with 4 cores. The underlying storage was 4 disks configured as RAID-0 as this was the best configuration of storage I had available. Swap is on a separate disk. Dirty ratio was tuned to 40% instead of the default of 20%. Testing was run with and without monitors to both verify that the patches were operating as expected and that any performance gain was real and not due to interference from monitors. Here is a summary of results based on testing XFS. 512M1P-xfs Files/s mean 32.69 ( 0.00%) 34.44 ( 5.08%) 512M1P-xfs Elapsed Time fsmark 51.41 48.29 512M1P-xfs Elapsed Time simple-wb 114.09 108.61 512M1P-xfs Elapsed Time mmap-strm 113.46 109.34 512M1P-xfs Kswapd efficiency fsmark 62% 63% 512M1P-xfs Kswapd efficiency simple-wb 56% 61% 512M1P-xfs Kswapd efficiency mmap-strm 44% 42% 512M-xfs Files/s mean 30.78 ( 0.00%) 35.94 (14.36%) 512M-xfs Elapsed Time fsmark 56.08 48.90 512M-xfs Elapsed Time simple-wb 112.22 98.13 512M-xfs Elapsed Time mmap-strm 219.15 196.67 512M-xfs Kswapd efficiency fsmark 54% 56% 512M-xfs Kswapd efficiency simple-wb 54% 55% 512M-xfs Kswapd efficiency mmap-strm 45% 44% 512M-4X-xfs Files/s mean 30.31 ( 0.00%) 33.33 ( 9.06%) 512M-4X-xfs Elapsed Time fsmark 63.26 55.88 512M-4X-xfs Elapsed Time simple-wb 100.90 90.25 512M-4X-xfs Elapsed Time mmap-strm 261.73 255.38 512M-4X-xfs Kswapd efficiency fsmark 49% 50% 512M-4X-xfs Kswapd efficiency simple-wb 54% 56% 512M-4X-xfs Kswapd efficiency mmap-strm 37% 36% 512M-16X-xfs Files/s mean 60.89 ( 0.00%) 65.22 ( 6.64%) 512M-16X-xfs Elapsed Time fsmark 67.47 58.25 512M-16X-xfs Elapsed Time simple-wb 103.22 90.89 512M-16X-xfs Elapsed Time mmap-strm 237.09 198.82 512M-16X-xfs Kswapd efficiency fsmark 45% 46% 512M-16X-xfs Kswapd efficiency simple-wb 53% 55% 512M-16X-xfs Kswapd efficiency mmap-strm 33% 33% Up until 512-4X, the FSmark improvements were statistically significant. For the 4X and 16X tests the results were within standard deviations but just barely. The time to completion for all tests is improved which is an important result. In general, kswapd efficiency is not affected by skipping dirty pages. 1024M1P-xfs Files/s mean 39.09 ( 0.00%) 41.15 ( 5.01%) 1024M1P-xfs Elapsed Time fsmark 84.14 80.41 1024M1P-xfs Elapsed Time simple-wb 210.77 184.78 1024M1P-xfs Elapsed Time mmap-strm 162.00 160.34 1024M1P-xfs Kswapd efficiency fsmark 69% 75% 1024M1P-xfs Kswapd efficiency simple-wb 71% 77% 1024M1P-xfs Kswapd efficiency mmap-strm 43% 44% 1024M-xfs Files/s mean 35.45 ( 0.00%) 37.00 ( 4.19%) 1024M-xfs Elapsed Time fsmark 94.59 91.00 1024M-xfs Elapsed Time simple-wb 229.84 195.08 1024M-xfs Elapsed Time mmap-strm 405.38 440.29 1024M-xfs Kswapd efficiency fsmark 79% 71% 1024M-xfs Kswapd efficiency simple-wb 74% 74% 1024M-xfs Kswapd efficiency mmap-strm 39% 42% 1024M-4X-xfs Files/s mean 32.63 ( 0.00%) 35.05 ( 6.90%) 1024M-4X-xfs Elapsed Time fsmark 103.33 97.74 1024M-4X-xfs Elapsed Time simple-wb 204.48 178.57 1024M-4X-xfs Elapsed Time mmap-strm 528.38 511.88 1024M-4X-xfs Kswapd efficiency fsmark 81% 70% 1024M-4X-xfs Kswapd efficiency simple-wb 73% 72% 1024M-4X-xfs Kswapd efficiency mmap-strm 39% 38% 1024M-16X-xfs Files/s mean 42.65 ( 0.00%) 42.97 ( 0.74%) 1024M-16X-xfs Elapsed Time fsmark 103.11 99.11 1024M-16X-xfs Elapsed Time simple-wb 200.83 178.24 1024M-16X-xfs Elapsed Time mmap-strm 397.35 459.82 1024M-16X-xfs Kswapd efficiency fsmark 84% 69% 1024M-16X-xfs Kswapd efficiency simple-wb 74% 73% 1024M-16X-xfs Kswapd efficiency mmap-strm 39% 40% All FSMark tests up to 16X had statistically significant improvements. For the most part, tests are completing faster with the exception of the streaming writes to a mixture of anonymous and file-backed mappings which were slower in two cases In the cases where the mmap-strm tests were slower, there was more swapping due to dirty pages being skipped. The number of additional pages swapped is almost identical to the fewer number of pages written from reclaim. In other words, roughly the same number of pages were reclaimed but swapping was slower. As the test is a bit unrealistic and stresses memory heavily, the small shift is acceptable. 4608M1P-xfs Files/s mean 29.75 ( 0.00%) 30.96 ( 3.91%) 4608M1P-xfs Elapsed Time fsmark 512.01 492.15 4608M1P-xfs Elapsed Time simple-wb 618.18 566.24 4608M1P-xfs Elapsed Time mmap-strm 488.05 465.07 4608M1P-xfs Kswapd efficiency fsmark 93% 86% 4608M1P-xfs Kswapd efficiency simple-wb 88% 84% 4608M1P-xfs Kswapd efficiency mmap-strm 46% 45% 4608M-xfs Files/s mean 27.60 ( 0.00%) 28.85 ( 4.33%) 4608M-xfs Elapsed Time fsmark 555.96 532.34 4608M-xfs Elapsed Time simple-wb 659.72 571.85 4608M-xfs Elapsed Time mmap-strm 1082.57 1146.38 4608M-xfs Kswapd efficiency fsmark 89% 91% 4608M-xfs Kswapd efficiency simple-wb 88% 82% 4608M-xfs Kswapd efficiency mmap-strm 48% 46% 4608M-4X-xfs Files/s mean 26.00 ( 0.00%) 27.47 ( 5.35%) 4608M-4X-xfs Elapsed Time fsmark 592.91 564.00 4608M-4X-xfs Elapsed Time simple-wb 616.65 575.07 4608M-4X-xfs Elapsed Time mmap-strm 1773.02 1631.53 4608M-4X-xfs Kswapd efficiency fsmark 90% 94% 4608M-4X-xfs Kswapd efficiency simple-wb 87% 82% 4608M-4X-xfs Kswapd efficiency mmap-strm 43% 43% 4608M-16X-xfs Files/s mean 26.07 ( 0.00%) 26.42 ( 1.32%) 4608M-16X-xfs Elapsed Time fsmark 602.69 585.78 4608M-16X-xfs Elapsed Time simple-wb 606.60 573.81 4608M-16X-xfs Elapsed Time mmap-strm 1549.75 1441.86 4608M-16X-xfs Kswapd efficiency fsmark 98% 98% 4608M-16X-xfs Kswapd efficiency simple-wb 88% 82% 4608M-16X-xfs Kswapd efficiency mmap-strm 44% 42% Unlike the other tests, the fsmark results are not statistically significant but the min and max times are both improved and for the most part, tests completed faster. There are other indications that this is an improvement as well. For example, in the vast majority of cases, there were fewer pages scanned by direct reclaim implying in many cases that stalls due to direct reclaim are reduced. KSwapd is scanning more due to skipping dirty pages which is unfortunate but the CPU usage is still acceptable In an earlier set of tests, I used blktrace and in almost all cases throughput throughout the entire test was higher. However, I ended up discarding those results as recording blktrace data was too heavy for my liking. On a laptop, I plugged in a USB stick and ran a similar tests of tests using it as backing storage. A desktop environment was running and for the entire duration of the tests, firefox and gnome terminal were launching and exiting to vaguely simulate a user. 1024M-xfs Files/s mean 0.41 ( 0.00%) 0.44 ( 6.82%) 1024M-xfs Elapsed Time fsmark 2053.52 1641.03 1024M-xfs Elapsed Time simple-wb 1229.53 768.05 1024M-xfs Elapsed Time mmap-strm 4126.44 4597.03 1024M-xfs Kswapd efficiency fsmark 84% 85% 1024M-xfs Kswapd efficiency simple-wb 92% 81% 1024M-xfs Kswapd efficiency mmap-strm 60% 51% 1024M-xfs Avg wait ms fsmark 5404.53 4473.87 1024M-xfs Avg wait ms simple-wb 2541.35 1453.54 1024M-xfs Avg wait ms mmap-strm 3400.25 3852.53 The mmap-strm results were hurt because firefox launching had a tendency to push the test out of memory. On the postive side, firefox launched marginally faster with the patches applied. Time to completion for many tests was faster but more importantly - the "Avg wait" time as measured by iostat was far lower implying the system would be more responsive. It was also the case that "Avg wait ms" on the root filesystem was lower. I tested it manually and while the system felt slightly more responsive while copying data to a USB stick, it was marginal enough that it could be my imagination. This patch: do not writeback filesystem pages in direct reclaim. When kswapd is failing to keep zones above the min watermark, a process will enter direct reclaim in the same manner kswapd does. If a dirty page is encountered during the scan, this page is written to backing storage using mapping->writepage. This causes two problems. First, it can result in very deep call stacks, particularly if the target storage or filesystem are complex. Some filesystems ignore write requests from direct reclaim as a result. The second is that a single-page flush is inefficient in terms of IO. While there is an expectation that the elevator will merge requests, this does not always happen. Quoting Christoph Hellwig; The elevator has a relatively small window it can operate on, and can never fix up a bad large scale writeback pattern. This patch prevents direct reclaim writing back filesystem pages by checking if current is kswapd. Anonymous pages are still written to swap as there is not the equivalent of a flusher thread for anonymous pages. If the dirty pages cannot be written back, they are placed back on the LRU lists. There is now a direct dependency on dirty page balancing to prevent too many pages in the system being dirtied which would prevent reclaim making forward progress. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Alex Elder <aelder@sgi.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f11c0ca5 |
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31-Oct-2011 |
Johannes Weiner <jweiner@redhat.com> |
mm: vmscan: drop nr_force_scan[] from get_scan_count The nr_force_scan[] tuple holds the effective scan numbers for anon and file pages in case the situation called for a forced scan and the regularly calculated scan numbers turned out zero. However, the effective scan number can always be assumed to be SWAP_CLUSTER_MAX right before the division into anon and file. The numerators and denominator are properly set up for all cases, be it force scan for just file, just anon, or both, to do the right thing. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3da367c3 |
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31-Oct-2011 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: add block plug for page reclaim per-task block plug can reduce block queue lock contention and increase request merge. Currently page reclaim doesn't support it. I originally thought page reclaim doesn't need it, because kswapd thread count is limited and file cache write is done at flusher mostly. When I test a workload with heavy swap in a 4-node machine, each CPU is doing direct page reclaim and swap. This causes block queue lock contention. In my test, without below patch, the CPU utilization is about 2% ~ 7%. With the patch, the CPU utilization is about 1% ~ 3%. Disk throughput isn't changed. This should improve normal kswapd write and file cache write too (increase request merge for example), but might not be so obvious as I explain above. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f80c0673 |
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31-Oct-2011 |
Minchan Kim <minchan.kim@gmail.com> |
mm: zone_reclaim: make isolate_lru_page() filter-aware In __zone_reclaim case, we don't want to shrink mapped page. Nonetheless, we have isolated mapped page and re-add it into LRU's head. It's unnecessary CPU overhead and makes LRU churning. Of course, when we isolate the page, the page might be mapped but when we try to migrate the page, the page would be not mapped. So it could be migrated. But race is rare and although it happens, it's no big deal. Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
39deaf85 |
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31-Oct-2011 |
Minchan Kim <minchan.kim@gmail.com> |
mm: compaction: make isolate_lru_page() filter-aware In async mode, compaction doesn't migrate dirty or writeback pages. So, it's meaningless to pick the page and re-add it to lru list. Of course, when we isolate the page in compaction, the page might be dirty or writeback but when we try to migrate the page, the page would be not dirty, writeback. So it could be migrated. But it's very unlikely as isolate and migration cycle is much faster than writeout. So, this patch helps cpu overhead and prevent unnecessary LRU churning. Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4356f21d |
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31-Oct-2011 |
Minchan Kim <minchan.kim@gmail.com> |
mm: change isolate mode from #define to bitwise type Change ISOLATE_XXX macro with bitwise isolate_mode_t type. Normally, macro isn't recommended as it's type-unsafe and making debugging harder as symbol cannot be passed throught to the debugger. Quote from Johannes " Hmm, it would probably be cleaner to fully convert the isolation mode into independent flags. INACTIVE, ACTIVE, BOTH is currently a tri-state among flags, which is a bit ugly." This patch moves isolate mode from swap.h to mmzone.h by memcontrol.h Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0e175a18 |
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07-Oct-2011 |
Curt Wohlgemuth <curtw@google.com> |
writeback: Add a 'reason' to wb_writeback_work This creates a new 'reason' field in a wb_writeback_work structure, which unambiguously identifies who initiates writeback activity. A 'wb_reason' enumeration has been added to writeback.h, to enumerate the possible reasons. The 'writeback_work_class' and tracepoint event class and 'writeback_queue_io' tracepoints are updated to include the symbolic 'reason' in all trace events. And the 'writeback_inodes_sbXXX' family of routines has had a wb_stats parameter added to them, so callers can specify why writeback is being started. Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Curt Wohlgemuth <curtw@google.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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185efc0f |
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14-Sep-2011 |
Johannes Weiner <jweiner@redhat.com> |
memcg: Revert "memcg: add memory.vmscan_stat" Revert the post-3.0 commit 82f9d486e59f5 ("memcg: add memory.vmscan_stat"). The implementation of per-memcg reclaim statistics violates how memcg hierarchies usually behave: hierarchically. The reclaim statistics are accounted to child memcgs and the parent hitting the limit, but not to hierarchy levels in between. Usually, hierarchical statistics are perfectly recursive, with each level representing the sum of itself and all its children. Since this exports statistics to userspace, this may lead to confusion and problems with changing things after the release, so revert it now, we can try again later. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a4d3e9e7 |
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14-Sep-2011 |
Johannes Weiner <jweiner@redhat.com> |
mm: vmscan: fix force-scanning small targets without swap Without swap, anonymous pages are not scanned. As such, they should not count when considering force-scanning a small target if there is no swap. Otherwise, targets are not force-scanned even when their effective scan number is zero and the other conditions--kswapd/memcg--apply. This fixes 246e87a93934 ("memcg: fix get_scan_count() for small targets"). [akpm@linux-foundation.org: fix comment] Signed-off-by: Johannes Weiner <jweiner@redhat.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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439423f6 |
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25-Aug-2011 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: clear ZONE_CONGESTED for zone with good watermark ZONE_CONGESTED is only cleared in kswapd, but pages can be freed in any task. It's possible ZONE_CONGESTED isn't cleared in some cases: 1. the zone is already balanced just entering balance_pgdat() for order-0 because concurrent tasks free memory. In this case, later check will skip the zone as it's balanced so the flag isn't cleared. 2. high order balance fallbacks to order-0. quote from Mel: At the end of balance_pgdat(), kswapd uses the following logic; If reclaiming at high order { for each zone { if all_unreclaimable skip if watermark is not met order = 0 loop again /* watermark is met */ clear congested } } i.e. it clears ZONE_CONGESTED if it the zone is balanced. if not, it restarts balancing at order-0. However, if the higher zones are balanced for order-0, kswapd will miss clearing ZONE_CONGESTED as that only happens after a zone is shrunk. This can mean that wait_iff_congested() stalls unnecessarily. This patch makes kswapd clear ZONE_CONGESTED during its initial highmem->dma scan for zones that are already balanced. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f51bdd2e |
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25-Aug-2011 |
Shaohua Li <shaohua.li@intel.com> |
mm: fix a vmscan warning I get the below warning: BUG: using smp_processor_id() in preemptible [00000000] code: bash/746 caller is native_sched_clock+0x37/0x6e Pid: 746, comm: bash Tainted: G W 3.0.0+ #254 Call Trace: [<ffffffff813435c6>] debug_smp_processor_id+0xc2/0xdc [<ffffffff8104158d>] native_sched_clock+0x37/0x6e [<ffffffff81116219>] try_to_free_mem_cgroup_pages+0x7d/0x270 [<ffffffff8114f1f8>] mem_cgroup_force_empty+0x24b/0x27a [<ffffffff8114ff21>] ? sys_close+0x38/0x138 [<ffffffff8114ff21>] ? sys_close+0x38/0x138 [<ffffffff8114f257>] mem_cgroup_force_empty_write+0x17/0x19 [<ffffffff810c72fb>] cgroup_file_write+0xa8/0xba [<ffffffff811522d2>] vfs_write+0xb3/0x138 [<ffffffff8115241a>] sys_write+0x4a/0x71 [<ffffffff8114ffd9>] ? sys_close+0xf0/0x138 [<ffffffff8176deab>] system_call_fastpath+0x16/0x1b sched_clock() can't be used with preempt enabled. And we don't need fast approach to get clock here, so let's use ktime API. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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81d66c70 |
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23-Aug-2011 |
Justin P. Mattock <justinmattock@gmail.com> |
mm/vmscan.c: fix a typo in a comment "relaimed" to "reclaimed" Signed-off-by: Justin P. Mattock <justinmattock@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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82f9d486 |
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26-Jul-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: add memory.vmscan_stat The commit log of 0ae5e89c60c9 ("memcg: count the soft_limit reclaim in...") says it adds scanning stats to memory.stat file. But it doesn't because we considered we needed to make a concensus for such new APIs. This patch is a trial to add memory.scan_stat. This shows - the number of scanned pages(total, anon, file) - the number of rotated pages(total, anon, file) - the number of freed pages(total, anon, file) - the number of elaplsed time (including sleep/pause time) for both of direct/soft reclaim. The biggest difference with oringinal Ying's one is that this file can be reset by some write, as # echo 0 ...../memory.scan_stat Example of output is here. This is a result after make -j 6 kernel under 300M limit. [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.scan_stat [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.vmscan_stat scanned_pages_by_limit 9471864 scanned_anon_pages_by_limit 6640629 scanned_file_pages_by_limit 2831235 rotated_pages_by_limit 4243974 rotated_anon_pages_by_limit 3971968 rotated_file_pages_by_limit 272006 freed_pages_by_limit 2318492 freed_anon_pages_by_limit 962052 freed_file_pages_by_limit 1356440 elapsed_ns_by_limit 351386416101 scanned_pages_by_system 0 scanned_anon_pages_by_system 0 scanned_file_pages_by_system 0 rotated_pages_by_system 0 rotated_anon_pages_by_system 0 rotated_file_pages_by_system 0 freed_pages_by_system 0 freed_anon_pages_by_system 0 freed_file_pages_by_system 0 elapsed_ns_by_system 0 scanned_pages_by_limit_under_hierarchy 9471864 scanned_anon_pages_by_limit_under_hierarchy 6640629 scanned_file_pages_by_limit_under_hierarchy 2831235 rotated_pages_by_limit_under_hierarchy 4243974 rotated_anon_pages_by_limit_under_hierarchy 3971968 rotated_file_pages_by_limit_under_hierarchy 272006 freed_pages_by_limit_under_hierarchy 2318492 freed_anon_pages_by_limit_under_hierarchy 962052 freed_file_pages_by_limit_under_hierarchy 1356440 elapsed_ns_by_limit_under_hierarchy 351386416101 scanned_pages_by_system_under_hierarchy 0 scanned_anon_pages_by_system_under_hierarchy 0 scanned_file_pages_by_system_under_hierarchy 0 rotated_pages_by_system_under_hierarchy 0 rotated_anon_pages_by_system_under_hierarchy 0 rotated_file_pages_by_system_under_hierarchy 0 freed_pages_by_system_under_hierarchy 0 freed_anon_pages_by_system_under_hierarchy 0 freed_file_pages_by_system_under_hierarchy 0 elapsed_ns_by_system_under_hierarchy 0 total_xxxx is for hierarchy management. This will be useful for further memcg developments and need to be developped before we do some complicated rework on LRU/softlimit management. This patch adds a new struct memcg_scanrecord into scan_control struct. sc->nr_scanned at el is not designed for exporting information. For example, nr_scanned is reset frequentrly and incremented +2 at scanning mapped pages. To avoid complexity, I added a new param in scan_control which is for exporting scanning score. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Cc: Andrew Bresticker <abrestic@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4508378b95 |
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26-Jul-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: fix vmscan count in small memcgs Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets") fixes the memcg/kswapd behavior against small targets and prevent vmscan priority too high. But the implementation is too naive and adds another problem to small memcg. It always force scan to 32 pages of file/anon and doesn't handle swappiness and other rotate_info. It makes vmscan to scan anon LRU regardless of swappiness and make reclaim bad. This patch fixes it by adjusting scanning count with regard to swappiness at el. At a test "cat 1G file under 300M limit." (swappiness=20) before patch scanned_pages_by_limit 360919 scanned_anon_pages_by_limit 180469 scanned_file_pages_by_limit 180450 rotated_pages_by_limit 31 rotated_anon_pages_by_limit 25 rotated_file_pages_by_limit 6 freed_pages_by_limit 180458 freed_anon_pages_by_limit 19 freed_file_pages_by_limit 180439 elapsed_ns_by_limit 429758872 after patch scanned_pages_by_limit 180674 scanned_anon_pages_by_limit 24 scanned_file_pages_by_limit 180650 rotated_pages_by_limit 35 rotated_anon_pages_by_limit 24 rotated_file_pages_by_limit 11 freed_pages_by_limit 180634 freed_anon_pages_by_limit 0 freed_file_pages_by_limit 180634 elapsed_ns_by_limit 367119089 scanned_pages_by_system 0 the numbers of scanning anon are decreased(as expected), and elapsed time reduced. By this patch, small memcgs will work better. (*) Because the amount of file-cache is much bigger than anon, recalaim_stat's rotate-scan counter make scanning files more. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bb2a0de9 |
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26-Jul-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: consolidate memory cgroup lru stat functions In mm/memcontrol.c, there are many lru stat functions as.. mem_cgroup_zone_nr_lru_pages mem_cgroup_node_nr_file_lru_pages mem_cgroup_nr_file_lru_pages mem_cgroup_node_nr_anon_lru_pages mem_cgroup_nr_anon_lru_pages mem_cgroup_node_nr_unevictable_lru_pages mem_cgroup_nr_unevictable_lru_pages mem_cgroup_node_nr_lru_pages mem_cgroup_nr_lru_pages mem_cgroup_get_local_zonestat Some of them are under #ifdef MAX_NUMNODES >1 and others are not. This seems bad. This patch consolidates all functions into mem_cgroup_zone_nr_lru_pages() mem_cgroup_node_nr_lru_pages() mem_cgroup_nr_lru_pages() For these functions, "which LRU?" information is passed by a mask. example: mem_cgroup_nr_lru_pages(mem, BIT(LRU_ACTIVE_ANON)) And I added some macro as ALL_LRU, ALL_LRU_FILE, ALL_LRU_ANON. example: mem_cgroup_nr_lru_pages(mem, ALL_LRU) BTW, considering layout of NUMA memory placement of counters, this patch seems to be better. Now, when we gather all LRU information, we scan in following orer for_each_lru -> for_each_node -> for_each_zone. This means we'll touch cache lines in different node in turn. After patch, we'll scan for_each_node -> for_each_zone -> for_each_lru(mask) Then, we'll gather information in the same cacheline at once. [akpm@linux-foundation.org: fix warnigns, build error] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1f4c025b |
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26-Jul-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: export memory cgroup's swappiness with mem_cgroup_swappiness() Each memory cgroup has a 'swappiness' value which can be accessed by get_swappiness(memcg). The major user is try_to_free_mem_cgroup_pages() and swappiness is passed by argument. It's propagated by scan_control. get_swappiness() is a static function but some planned updates will need to get swappiness from files other than memcontrol.c This patch exports get_swappiness() as mem_cgroup_swappiness(). With this, we can remove the argument of swapiness from try_to_free... and drop swappiness from scan_control. only memcg uses it. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e9299f50 |
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07-Jul-2011 |
Dave Chinner <dchinner@redhat.com> |
vmscan: add customisable shrinker batch size For shrinkers that have their own cond_resched* calls, having shrink_slab break the work down into small batches is not paticularly efficient. Add a custom batchsize field to the struct shrinker so that shrinkers can use a larger batch size if they desire. A value of zero (uninitialised) means "use the default", so behaviour is unchanged by this patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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3567b59a |
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07-Jul-2011 |
Dave Chinner <dchinner@redhat.com> |
vmscan: reduce wind up shrinker->nr when shrinker can't do work When a shrinker returns -1 to shrink_slab() to indicate it cannot do any work given the current memory reclaim requirements, it adds the entire total_scan count to shrinker->nr. The idea ehind this is that whenteh shrinker is next called and can do work, it will do the work of the previously aborted shrinker call as well. However, if a filesystem is doing lots of allocation with GFP_NOFS set, then we get many, many more aborts from the shrinkers than we do successful calls. The result is that shrinker->nr winds up to it's maximum permissible value (twice the current cache size) and then when the next shrinker call that can do work is issued, it has enough scan count built up to free the entire cache twice over. This manifests itself in the cache going from full to empty in a matter of seconds, even when only a small part of the cache is needed to be emptied to free sufficient memory. Under metadata intensive workloads on ext4 and XFS, I'm seeing the VFS caches increase memory consumption up to 75% of memory (no page cache pressure) over a period of 30-60s, and then the shrinker empties them down to zero in the space of 2-3s. This cycle repeats over and over again, with the shrinker completely trashing the inode and dentry caches every minute or so the workload continues. This behaviour was made obvious by the shrink_slab tracepoints added earlier in the series, and made worse by the patch that corrected the concurrent accounting of shrinker->nr. To avoid this problem, stop repeated small increments of the total scan value from winding shrinker->nr up to a value that can cause the entire cache to be freed. We still need to allow it to wind up, so use the delta as the "large scan" threshold check - if the delta is more than a quarter of the entire cache size, then it is a large scan and allowed to cause lots of windup because we are clearly needing to free lots of memory. If it isn't a large scan then limit the total scan to half the size of the cache so that windup never increases to consume the whole cache. Reducing the total scan limit further does not allow enough wind-up to maintain the current levels of performance, whilst a higher threshold does not prevent the windup from freeing the entire cache under sustained workloads. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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acf92b48 |
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07-Jul-2011 |
Dave Chinner <dchinner@redhat.com> |
vmscan: shrinker->nr updates race and go wrong shrink_slab() allows shrinkers to be called in parallel so the struct shrinker can be updated concurrently. It does not provide any exclusio for such updates, so we can get the shrinker->nr value increasing or decreasing incorrectly. As a result, when a shrinker repeatedly returns a value of -1 (e.g. a VFS shrinker called w/ GFP_NOFS), the shrinker->nr goes haywire, sometimes updating with the scan count that wasn't used, sometimes losing it altogether. Worse is when a shrinker does work and that update is lost due to racy updates, which means the shrinker will do the work again! Fix this by making the total_scan calculations independent of shrinker->nr, and making the shrinker->nr updates atomic w.r.t. to other updates via cmpxchg loops. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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09576073 |
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07-Jul-2011 |
Dave Chinner <dchinner@redhat.com> |
vmscan: add shrink_slab tracepoints It is impossible to understand what the shrinkers are actually doing without instrumenting the code, so add a some tracepoints to allow insight to be gained. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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4746efde |
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19-Jul-2011 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: fix a livelock in kswapd I'm running a workload which triggers a lot of swap in a machine with 4 nodes. After I kill the workload, I found a kswapd livelock. Sometimes kswapd3 or kswapd2 are keeping running and I can't access filesystem, but most memory is free. This looks like a regression since commit 08951e545918c159 ("mm: vmscan: correct check for kswapd sleeping in sleeping_prematurely"). Node 2 and 3 have only ZONE_NORMAL, but balance_pgdat() will return 0 for classzone_idx. The reason is end_zone in balance_pgdat() is 0 by default, if all zones have watermark ok, end_zone will keep 0. Later sleeping_prematurely() always returns true. Because this is an order 3 wakeup, and if classzone_idx is 0, both balanced_pages and present_pages in pgdat_balanced() are 0. We add a special case here. If a zone has no page, we think it's balanced. This fixes the livelock. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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215ddd66 |
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08-Jul-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: only read new_classzone_idx from pgdat when reclaiming successfully During allocator-intensive workloads, kswapd will be woken frequently causing free memory to oscillate between the high and min watermark. This is expected behaviour. Unfortunately, if the highest zone is small, a problem occurs. When balance_pgdat() returns, it may be at a lower classzone_idx than it started because the highest zone was unreclaimable. Before checking if it should go to sleep though, it checks pgdat->classzone_idx which when there is no other activity will be MAX_NR_ZONES-1. It interprets this as it has been woken up while reclaiming, skips scheduling and reclaims again. As there is no useful reclaim work to do, it enters into a loop of shrinking slab consuming loads of CPU until the highest zone becomes reclaimable for a long period of time. There are two problems here. 1) If the returned classzone or order is lower, it'll continue reclaiming without scheduling. 2) if the highest zone was marked unreclaimable but balance_pgdat() returns immediately at DEF_PRIORITY, the new lower classzone is not communicated back to kswapd() for sleeping. This patch does two things that are related. If the end_zone is unreclaimable, this information is communicated back. Second, if the classzone or order was reduced due to failing to reclaim, new information is not read from pgdat and instead an attempt is made to go to sleep. Due to this, it is also necessary that pgdat->classzone_idx be initialised each time to pgdat->nr_zones - 1 to avoid re-reads being interpreted as wakeups. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Pádraig Brady <P@draigBrady.com> Tested-by: Pádraig Brady <P@draigBrady.com> Tested-by: Andrew Lutomirski <luto@mit.edu> Acked-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
da175d06 |
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08-Jul-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: evaluate the watermarks against the correct classzone When deciding if kswapd is sleeping prematurely, the classzone is taken into account but this is different to what balance_pgdat() and the allocator are doing. Specifically, the DMA zone will be checked based on the classzone used when waking kswapd which could be for a GFP_KERNEL or GFP_HIGHMEM request. The lowmem reserve limit kicks in, the watermark is not met and kswapd thinks it's sleeping prematurely keeping kswapd awake in error. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Pádraig Brady <P@draigBrady.com> Tested-by: Pádraig Brady <P@draigBrady.com> Tested-by: Andrew Lutomirski <luto@mit.edu> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d7868dae |
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08-Jul-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: do not apply pressure to slab if we are not applying pressure to zone During allocator-intensive workloads, kswapd will be woken frequently causing free memory to oscillate between the high and min watermark. This is expected behaviour. When kswapd applies pressure to zones during node balancing, it checks if the zone is above a high+balance_gap threshold. If it is, it does not apply pressure but it unconditionally shrinks slab on a global basis which is excessive. In the event kswapd is being kept awake due to a high small unreclaimable zone, it skips zone shrinking but still calls shrink_slab(). Once pressure has been applied, the check for zone being unreclaimable is being made before the check is made if all_unreclaimable should be set. This miss of unreclaimable can cause has_under_min_watermark_zone to be set due to an unreclaimable zone preventing kswapd backing off on congestion_wait(). Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Pádraig Brady <P@draigBrady.com> Tested-by: Pádraig Brady <P@draigBrady.com> Tested-by: Andrew Lutomirski <luto@mit.edu> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
08951e54 |
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08-Jul-2011 |
Mel Gorman <mgorman@suse.de> |
mm: vmscan: correct check for kswapd sleeping in sleeping_prematurely During allocator-intensive workloads, kswapd will be woken frequently causing free memory to oscillate between the high and min watermark. This is expected behaviour. Unfortunately, if the highest zone is small, a problem occurs. This seems to happen most with recent sandybridge laptops but it's probably a co-incidence as some of these laptops just happen to have a small Normal zone. The reproduction case is almost always during copying large files that kswapd pegs at 100% CPU until the file is deleted or cache is dropped. The problem is mostly down to sleeping_prematurely() keeping kswapd awake when the highest zone is small and unreclaimable and compounded by the fact we shrink slabs even when not shrinking zones causing a lot of time to be spent in shrinkers and a lot of memory to be reclaimed. Patch 1 corrects sleeping_prematurely to check the zones matching the classzone_idx instead of all zones. Patch 2 avoids shrinking slab when we are not shrinking a zone. Patch 3 notes that sleeping_prematurely is checking lower zones against a high classzone which is not what allocators or balance_pgdat() is doing leading to an artifical belief that kswapd should be still awake. Patch 4 notes that when balance_pgdat() gives up on a high zone that the decision is not communicated to sleeping_prematurely() This problem affects 2.6.38.8 for certain and is expected to affect 2.6.39 and 3.0-rc4 as well. If accepted, they need to go to -stable to be picked up by distros and this series is against 3.0-rc4. I've cc'd people that reported similar problems recently to see if they still suffer from the problem and if this fixes it. This patch: correct the check for kswapd sleeping in sleeping_prematurely() During allocator-intensive workloads, kswapd will be woken frequently causing free memory to oscillate between the high and min watermark. This is expected behaviour. A problem occurs if the highest zone is small. balance_pgdat() only considers unreclaimable zones when priority is DEF_PRIORITY but sleeping_prematurely considers all zones. It's possible for this sequence to occur 1. kswapd wakes up and enters balance_pgdat() 2. At DEF_PRIORITY, marks highest zone unreclaimable 3. At DEF_PRIORITY-1, ignores highest zone setting end_zone 4. At DEF_PRIORITY-1, calls shrink_slab freeing memory from highest zone, clearing all_unreclaimable. Highest zone is still unbalanced 5. kswapd returns and calls sleeping_prematurely 6. sleeping_prematurely looks at *all* zones, not just the ones being considered by balance_pgdat. The highest small zone has all_unreclaimable cleared but the zone is not balanced. all_zones_ok is false so kswapd stays awake This patch corrects the behaviour of sleeping_prematurely to check the zones balance_pgdat() checked. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Pádraig Brady <P@draigBrady.com> Tested-by: Pádraig Brady <P@draigBrady.com> Tested-by: Andrew Lutomirski <luto@mit.edu> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ac34a1a3 |
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27-Jun-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: fix direct softlimit reclaim to be called in limit path Commit d149e3b25d7c ("memcg: add the soft_limit reclaim in global direct reclaim") adds a softlimit hook to shrink_zones(). By this, soft limit is called as try_to_free_pages() do_try_to_free_pages() shrink_zones() mem_cgroup_soft_limit_reclaim() Then, direct reclaim is memcg softlimit hint aware, now. But, the memory cgroup's "limit" path can call softlimit shrinker. try_to_free_mem_cgroup_pages() do_try_to_free_pages() shrink_zones() mem_cgroup_soft_limit_reclaim() This will cause a global reclaim when a memcg hits limit. This is bug. soft_limit_reclaim() should be called when scanning_global_lru(sc) == true. And the commit adds a variable "total_scanned" for counting softlimit scanned pages....it's not "total". This patch removes the variable and update sc->nr_scanned instead of it. This will affect shrink_slab()'s scan condition but, global LRU is scanned by softlimit and I think this change makes sense. TODO: avoid too much scanning of a zone when softlimit did enough work. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Ying Han <yinghan@google.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d179e84b |
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15-Jun-2011 |
Andrea Arcangeli <aarcange@redhat.com> |
mm: vmscan: do not use page_count without a page pin It is unsafe to run page_count during the physical pfn scan because compound_head could trip on a dangling pointer when reading page->first_page if the compound page is being freed by another CPU. [mgorman@suse.de: split out patch] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a433658c |
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15-Jun-2011 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan,memcg: memcg aware swap token Currently, memcg reclaim can disable swap token even if the swap token mm doesn't belong in its memory cgroup. It's slightly risky. If an admin creates very small mem-cgroup and silly guy runs contentious heavy memory pressure workload, every tasks are going to lose swap token and then system may become unresponsive. That's bad. This patch adds 'memcg' parameter into disable_swap_token(). and if the parameter doesn't match swap token, VM doesn't disable it. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Rik van Riel<riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1bac180b |
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26-May-2011 |
Ying Han <yinghan@google.com> |
memcg: rename mem_cgroup_zone_nr_pages() to mem_cgroup_zone_nr_lru_pages() The caller of the function has been renamed to zone_nr_lru_pages(), and this is just fixing up in the memcg code. The current name is easily to be mis-read as zone's total number of pages. Signed-off-by: Ying Han <yinghan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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246e87a9 |
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26-May-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: fix get_scan_count() for small targets During memory reclaim we determine the number of pages to be scanned per zone as (anon + file) >> priority. Assume scan = (anon + file) >> priority. If scan < SWAP_CLUSTER_MAX, the scan will be skipped for this time and priority gets higher. This has some problems. 1. This increases priority as 1 without any scan. To do scan in this priority, amount of pages should be larger than 512M. If pages>>priority < SWAP_CLUSTER_MAX, it's recorded and scan will be batched, later. (But we lose 1 priority.) If memory size is below 16M, pages >> priority is 0 and no scan in DEF_PRIORITY forever. 2. If zone->all_unreclaimabe==true, it's scanned only when priority==0. So, x86's ZONE_DMA will never be recoverred until the user of pages frees memory by itself. 3. With memcg, the limit of memory can be small. When using small memcg, it gets priority < DEF_PRIORITY-2 very easily and need to call wait_iff_congested(). For doing scan before priorty=9, 64MB of memory should be used. Then, this patch tries to scan SWAP_CLUSTER_MAX of pages in force...when 1. the target is enough small. 2. it's kswapd or memcg reclaim. Then we can avoid rapid priority drop and may be able to recover all_unreclaimable in a small zones. And this patch removes nr_saved_scan. This will allow scanning in this priority even when pages >> priority is very small. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Ying Han <yinghan@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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889976db |
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26-May-2011 |
Ying Han <yinghan@google.com> |
memcg: reclaim memory from nodes in round-robin order Presently, memory cgroup's direct reclaim frees memory from the current node. But this has some troubles. Usually when a set of threads works in a cooperative way, they tend to operate on the same node. So if they hit limits under memcg they will reclaim memory from themselves, damaging the active working set. For example, assume 2 node system which has Node 0 and Node 1 and a memcg which has 1G limit. After some work, file cache remains and the usages are Node 0: 1M Node 1: 998M. and run an application on Node 0, it will eat its foot before freeing unnecessary file caches. This patch adds round-robin for NUMA and adds equal pressure to each node. When using cpuset's spread memory feature, this will work very well. But yes, a better algorithm is needed. [akpm@linux-foundation.org: comment editing] [kamezawa.hiroyu@jp.fujitsu.com: fix time comparisons] Signed-off-by: Ying Han <yinghan@google.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d149e3b2 |
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26-May-2011 |
Ying Han <yinghan@google.com> |
memcg: add the soft_limit reclaim in global direct reclaim. We recently added the change in global background reclaim which counts the return value of soft_limit reclaim. Now this patch adds the similar logic on global direct reclaim. We should skip scanning global LRU on shrink_zone if soft_limit reclaim does enough work. This is the first step where we start with counting the nr_scanned and nr_reclaimed from soft_limit reclaim into global scan_control. Signed-off-by: Ying Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0ae5e89c |
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26-May-2011 |
Ying Han <yinghan@google.com> |
memcg: count the soft_limit reclaim in global background reclaim The global kswapd scans per-zone LRU and reclaims pages regardless of the cgroup. It breaks memory isolation since one cgroup can end up reclaiming pages from another cgroup. Instead we should rely on memcg-aware target reclaim including per-memcg kswapd and soft_limit hierarchical reclaim under memory pressure. In the global background reclaim, we do soft reclaim before scanning the per-zone LRU. However, the return value is ignored. This patch is the first step to skip shrink_zone() if soft_limit reclaim does enough work. This is part of the effort which tries to reduce reclaiming pages in global LRU in memcg. The per-memcg background reclaim patchset further enhances the per-cgroup targetting reclaim, which I should have V4 posted shortly. Try running multiple memory intensive workloads within seperate memcgs. Watch the counters of soft_steal in memory.stat. $ cat /dev/cgroup/A/memory.stat | grep 'soft' soft_steal 240000 soft_scan 240000 total_soft_steal 240000 total_soft_scan 240000 This patch: In the global background reclaim, we do soft reclaim before scanning the per-zone LRU. However, the return value is ignored. We would like to skip shrink_zone() if soft_limit reclaim does enough work. Also, we need to make the memory pressure balanced across per-memcg zones, like the logic vm-core. This patch is the first step where we start with counting the nr_scanned and nr_reclaimed from soft_limit reclaim into the global scan_control. Signed-off-by: Ying Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1495f230 |
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24-May-2011 |
Ying Han <yinghan@google.com> |
vmscan: change shrinker API by passing shrink_control struct Change each shrinker's API by consolidating the existing parameters into shrink_control struct. This will simplify any further features added w/o touching each file of shrinker. [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix warning] [kosaki.motohiro@jp.fujitsu.com: fix up new shrinker API] [akpm@linux-foundation.org: fix xfs warning] [akpm@linux-foundation.org: update gfs2] Signed-off-by: Ying Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Acked-by: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a09ed5e0 |
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24-May-2011 |
Ying Han <yinghan@google.com> |
vmscan: change shrink_slab() interfaces by passing shrink_control Consolidate the existing parameters to shrink_slab() into a new shrink_control struct. This is needed later to pass the same struct to shrinkers. Signed-off-by: Ying Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Acked-by: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0c917313 |
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24-May-2011 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm: strictly require elevated page refcount in isolate_lru_page() isolate_lru_page() must be called only with stable reference to the page, this is what is written in the comment above it, this is reasonable. current isolate_lru_page() users and its page extra reference sources: mm/huge_memory.c: __collapse_huge_page_isolate() - reference from pte mm/memcontrol.c: mem_cgroup_move_parent() - get_page_unless_zero() mem_cgroup_move_charge_pte_range() - reference from pte mm/memory-failure.c: soft_offline_page() - fixed, reference from get_any_page() delete_from_lru_cache() - reference from caller or get_page_unless_zero() [ seems like there bug, because __memory_failure() can call page_action() for hpages tail, but it is ok for isolate_lru_page(), tail getted and not in lru] mm/memory_hotplug.c: do_migrate_range() - fixed, get_page_unless_zero() mm/mempolicy.c: migrate_page_add() - reference from pte mm/migrate.c: do_move_page_to_node_array() - reference from follow_page() mlock.c: - various external references mm/vmscan.c: putback_lru_page() - reference from isolate_lru_page() It seems that all isolate_lru_page() users are ready now for this restriction. So, let's replace redundant get_page_unless_zero() with get_page() and add page initial reference count check with VM_BUG_ON() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f06590bd |
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24-May-2011 |
Minchan Kim <minchan.kim@gmail.com> |
mm: vmscan: correctly check if reclaimer should schedule during shrink_slab It has been reported on some laptops that kswapd is consuming large amounts of CPU and not being scheduled when SLUB is enabled during large amounts of file copying. It is expected that this is due to kswapd missing every cond_resched() point because; shrink_page_list() calls cond_resched() if inactive pages were isolated which in turn may not happen if all_unreclaimable is set in shrink_zones(). If for whatver reason, all_unreclaimable is set on all zones, we can miss calling cond_resched(). balance_pgdat() only calls cond_resched if the zones are not balanced. For a high-order allocation that is balanced, it checks order-0 again. During that window, order-0 might have become unbalanced so it loops again for order-0 and returns that it was reclaiming for order-0 to kswapd(). It can then find that a caller has rewoken kswapd for a high-order and re-enters balance_pgdat() without ever calling cond_resched(). shrink_slab only calls cond_resched() if we are reclaiming slab pages. If there are a large number of direct reclaimers, the shrinker_rwsem can be contended and prevent kswapd calling cond_resched(). This patch modifies the shrink_slab() case. If the semaphore is contended, the caller will still check cond_resched(). After each successful call into a shrinker, the check for cond_resched() remains in case one shrinker is particularly slow. [mgorman@suse.de: preserve call to cond_resched after each call into shrinker] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Tested-by: Colin King <colin.king@canonical.com> Cc: Raghavendra D Prabhu <raghu.prabhu13@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Chris Mason <chris.mason@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: <stable@kernel.org> [2.6.38+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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afc7e326 |
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24-May-2011 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: vmscan: correct use of pgdat_balanced in sleeping_prematurely There are a few reports of people experiencing hangs when copying large amounts of data with kswapd using a large amount of CPU which appear to be due to recent reclaim changes. SLUB using high orders is the trigger but not the root cause as SLUB has been using high orders for a while. The root cause was bugs introduced into reclaim which are addressed by the following two patches. Patch 1 corrects logic introduced by commit 1741c877 ("mm: kswapd: keep kswapd awake for high-order allocations until a percentage of the node is balanced") to allow kswapd to go to sleep when balanced for high orders. Patch 2 notes that it is possible for kswapd to miss every cond_resched() and updates shrink_slab() so it'll at least reach that scheduling point. Chris Wood reports that these two patches in isolation are sufficient to prevent the system hanging. AFAIK, they should also resolve similar hangs experienced by James Bottomley. This patch: Johannes Weiner poined out that the logic in commit 1741c877 ("mm: kswapd: keep kswapd awake for high-order allocations until a percentage of the node is balanced") is backwards. Instead of allowing kswapd to go to sleep when balancing for high order allocations, it keeps it kswapd running uselessly. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Tested-by: Colin King <colin.king@canonical.com> Cc: Raghavendra D Prabhu <raghu.prabhu13@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Chris Mason <chris.mason@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Cc: <stable@kernel.org> [2.6.38+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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268bb0ce |
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20-May-2011 |
Linus Torvalds <torvalds@linux-foundation.org> |
sanitize <linux/prefetch.h> usage Commit e66eed651fd1 ("list: remove prefetching from regular list iterators") removed the include of prefetch.h from list.h, which uncovered several cases that had apparently relied on that rather obscure header file dependency. So this fixes things up a bit, using grep -L linux/prefetch.h $(git grep -l '[^a-z_]prefetchw*(' -- '*.[ch]') grep -L 'prefetchw*(' $(git grep -l 'linux/prefetch.h' -- '*.[ch]') to guide us in finding files that either need <linux/prefetch.h> inclusion, or have it despite not needing it. There are more of them around (mostly network drivers), but this gets many core ones. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d6c438b6 |
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17-May-2011 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: fix zone congestion ZONE_CONGESTED should be a state of global memory reclaim. If not, a busy memcg sets this and give unnecessary throttoling in wait_iff_congested() against memory recalim in other contexts. This makes system performance bad. I'll think about "memcg is congested!" flag is required or not, later. But this fix is required first. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Ying Han <yinghan@google.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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929bea7c |
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14-Apr-2011 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: all_unreclaimable() use zone->all_unreclaimable as a name all_unreclaimable check in direct reclaim has been introduced at 2.6.19 by following commit. 2006 Sep 25; commit 408d8544; oom: use unreclaimable info And it went through strange history. firstly, following commit broke the logic unintentionally. 2008 Apr 29; commit a41f24ea; page allocator: smarter retry of costly-order allocations Two years later, I've found obvious meaningless code fragment and restored original intention by following commit. 2010 Jun 04; commit bb21c7ce; vmscan: fix do_try_to_free_pages() return value when priority==0 But, the logic didn't works when 32bit highmem system goes hibernation and Minchan slightly changed the algorithm and fixed it . 2010 Sep 22: commit d1908362: vmscan: check all_unreclaimable in direct reclaim path But, recently, Andrey Vagin found the new corner case. Look, struct zone { .. int all_unreclaimable; .. unsigned long pages_scanned; .. } zone->all_unreclaimable and zone->pages_scanned are neigher atomic variables nor protected by lock. Therefore zones can become a state of zone->page_scanned=0 and zone->all_unreclaimable=1. In this case, current all_unreclaimable() return false even though zone->all_unreclaimabe=1. This resulted in the kernel hanging up when executing a loop of the form 1. fork 2. mmap 3. touch memory 4. read memory 5. munmmap as described in http://www.gossamer-threads.com/lists/linux/kernel/1348725#1348725 Is this ignorable minor issue? No. Unfortunately, x86 has very small dma zone and it become zone->all_unreclamble=1 easily. and if it become all_unreclaimable=1, it never restore all_unreclaimable=0. Why? if all_unreclaimable=1, vmscan only try DEF_PRIORITY reclaim and a-few-lru-pages>>DEF_PRIORITY always makes 0. that mean no page scan at all! Eventually, oom-killer never works on such systems. That said, we can't use zone->pages_scanned for this purpose. This patch restore all_unreclaimable() use zone->all_unreclaimable as old. and in addition, to add oom_killer_disabled check to avoid reintroduce the issue of commit d1908362 ("vmscan: check all_unreclaimable in direct reclaim path"). Reported-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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25985edc |
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30-Mar-2011 |
Lucas De Marchi <lucas.demarchi@profusion.mobi> |
Fix common misspellings Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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8afdcece |
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22-Mar-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: kswapd should not free an excessive number of pages when balancing small zones When reclaiming for order-0 pages, kswapd requires that all zones be balanced. Each cycle through balance_pgdat() does background ageing on all zones if necessary and applies equal pressure on the inactive zone unless a lot of pages are free already. A "lot of free pages" is defined as a "balance gap" above the high watermark which is currently 7*high_watermark. Historically this was reasonable as min_free_kbytes was small. However, on systems using huge pages, it is recommended that min_free_kbytes is higher and it is tuned with hugeadm --set-recommended-min_free_kbytes. With the introduction of transparent huge page support, this recommended value is also applied. On X86-64 with 4G of memory, min_free_kbytes becomes 67584 so one would expect around 68M of memory to be free. The Normal zone is approximately 35000 pages so under even normal memory pressure such as copying a large file, it gets exhausted quickly. As it is getting exhausted, kswapd applies pressure equally to all zones, including the DMA32 zone. DMA32 is approximately 700,000 pages with a high watermark of around 23,000 pages. In this situation, kswapd will reclaim around (23000*8 where 8 is the high watermark + balance gap of 7 * high watermark) pages or 718M of pages before the zone is ignored. What the user sees is that free memory far higher than it should be. To avoid an excessive number of pages being reclaimed from the larger zones, explicitely defines the "balance gap" to be either 1% of the zone or the low watermark for the zone, whichever is smaller. While kswapd will check all zones to apply pressure, it'll ignore zones that meets the (high_wmark + balance_gap) watermark. To test this, 80G were copied from a partition and the amount of memory being used was recorded. A comparison of a patch and unpatched kernel can be seen at http://www.csn.ul.ie/~mel/postings/minfree-20110222/memory-usage-hydra.ps and shows that kswapd is not reclaiming as much memory with the patch applied. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: "Chen, Tim C" <tim.c.chen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e64a782f |
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22-Mar-2011 |
Minchan Kim <minchan.kim@gmail.com> |
mm: change __remove_from_page_cache() Now we renamed remove_from_page_cache with delete_from_page_cache. As consistency of __remove_from_swap_cache and remove_from_swap_cache, we change internal page cache handling function name, too. Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d527caf2 |
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22-Mar-2011 |
Andrea Arcangeli <aarcange@redhat.com> |
mm: compaction: prevent kswapd compacting memory to reduce CPU usage This patch reverts 5a03b051 ("thp: use compaction in kswapd for GFP_ATOMIC order > 0") due to reports stating that kswapd CPU usage was higher and IRQs were being disabled more frequently. This was reported at http://www.spinics.net/linux/fedora/alsa-user/msg09885.html. Without this patch applied, CPU usage by kswapd hovers around the 20% mark according to the tester (Arthur Marsh: http://www.spinics.net/linux/fedora/alsa-user/msg09899.html). With this patch applied, it's around 2%. The problem is not related to THP which specifies __GFP_NO_KSWAPD but is triggered by high-order allocations hitting the low watermark for their order and waking kswapd on kernels with CONFIG_COMPACTION set. The most common trigger for this is network cards configured for jumbo frames but it's also possible it'll be triggered by fork-heavy workloads (order-1) and some wireless cards which depend on order-1 allocations. The symptoms for the user will be high CPU usage by kswapd in low-memory situations which could be confused with another writeback problem. While a patch like 5a03b051 may be reintroduced in the future, this patch plays it safe for now and reverts it. [mel@csn.ul.ie: Beefed up the changelog] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reported-by: Arthur Marsh <arthur.marsh@internode.on.net> Tested-by: Arthur Marsh <arthur.marsh@internode.on.net> Cc: <stable@kernel.org> [2.6.38.1] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7eaceacc |
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10-Mar-2011 |
Jens Axboe <jaxboe@fusionio.com> |
block: remove per-queue plugging Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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#
2876592f |
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25-Feb-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: stop reclaim/compaction earlier due to insufficient progress if !__GFP_REPEAT should_continue_reclaim() for reclaim/compaction allows scanning to continue even if pages are not being reclaimed until the full list is scanned. In terms of allocation success, this makes sense but potentially it introduces unwanted latency for high-order allocations such as transparent hugepages and network jumbo frames that would prefer to fail the allocation attempt and fallback to order-0 pages. Worse, there is a potential that the full LRU scan will clear all the young bits, distort page aging information and potentially push pages into swap that would have otherwise remained resident. This patch will stop reclaim/compaction if no pages were reclaimed in the last SWAP_CLUSTER_MAX pages that were considered. For allocations such as hugetlbfs that use __GFP_REPEAT and have fewer fallback options, the full LRU list may still be scanned. Order-0 allocation should not be affected because RECLAIM_MODE_COMPACTION is not set so the following avoids the gfp_mask being examined: if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION)) return false; A tool was developed based on ftrace that tracked the latency of high-order allocations while transparent hugepage support was enabled and three benchmarks were run. The "fix-infinite" figures are 2.6.38-rc4 with Johannes's patch "vmscan: fix zone shrinking exit when scan work is done" applied. STREAM Highorder Allocation Latency Statistics fix-infinite break-early 1 :: Count 10298 10229 1 :: Min 0.4560 0.4640 1 :: Mean 1.0589 1.0183 1 :: Max 14.5990 11.7510 1 :: Stddev 0.5208 0.4719 2 :: Count 2 1 2 :: Min 1.8610 3.7240 2 :: Mean 3.4325 3.7240 2 :: Max 5.0040 3.7240 2 :: Stddev 1.5715 0.0000 9 :: Count 111696 111694 9 :: Min 0.5230 0.4110 9 :: Mean 10.5831 10.5718 9 :: Max 38.4480 43.2900 9 :: Stddev 1.1147 1.1325 Mean time for order-1 allocations is reduced. order-2 looks increased but with so few allocations, it's not particularly significant. THP mean allocation latency is also reduced. That said, allocation time varies so significantly that the reductions are within noise. Max allocation time is reduced by a significant amount for low-order allocations but reduced for THP allocations which presumably are now breaking before reclaim has done enough work. SysBench Highorder Allocation Latency Statistics fix-infinite break-early 1 :: Count 15745 15677 1 :: Min 0.4250 0.4550 1 :: Mean 1.1023 1.0810 1 :: Max 14.4590 10.8220 1 :: Stddev 0.5117 0.5100 2 :: Count 1 1 2 :: Min 3.0040 2.1530 2 :: Mean 3.0040 2.1530 2 :: Max 3.0040 2.1530 2 :: Stddev 0.0000 0.0000 9 :: Count 2017 1931 9 :: Min 0.4980 0.7480 9 :: Mean 10.4717 10.3840 9 :: Max 24.9460 26.2500 9 :: Stddev 1.1726 1.1966 Again, mean time for order-1 allocations is reduced while order-2 allocations are too few to draw conclusions from. The mean time for THP allocations is also slightly reduced albeit the reductions are within varianes. Once again, our maximum allocation time is significantly reduced for low-order allocations and slightly increased for THP allocations. Anon stream mmap reference Highorder Allocation Latency Statistics 1 :: Count 1376 1790 1 :: Min 0.4940 0.5010 1 :: Mean 1.0289 0.9732 1 :: Max 6.2670 4.2540 1 :: Stddev 0.4142 0.2785 2 :: Count 1 - 2 :: Min 1.9060 - 2 :: Mean 1.9060 - 2 :: Max 1.9060 - 2 :: Stddev 0.0000 - 9 :: Count 11266 11257 9 :: Min 0.4990 0.4940 9 :: Mean 27250.4669 24256.1919 9 :: Max 11439211.0000 6008885.0000 9 :: Stddev 226427.4624 186298.1430 This benchmark creates one thread per CPU which references an amount of anonymous memory 1.5 times the size of physical RAM. This pounds swap quite heavily and is intended to exercise THP a bit. Mean allocation time for order-1 is reduced as before. It's also reduced for THP allocations but the variations here are pretty massive due to swap. As before, maximum allocation times are significantly reduced. Overall, the patch reduces the mean and maximum allocation latencies for the smaller high-order allocations. This was with Slab configured so it would be expected to be more significant with Slub which uses these size allocations more aggressively. The mean allocation times for THP allocations are also slightly reduced. The maximum latency was slightly increased as predicted by the comments due to reclaim/compaction breaking early. However, workloads care more about the latency of lower-order allocations than THP so it's an acceptable trade-off. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f0fdc5e8 |
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10-Feb-2011 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: fix zone shrinking exit when scan work is done Commit 3e7d34497067 ("mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaim") introduced an indefinite loop in shrink_zone(). It meant to break out of this loop when no pages had been reclaimed and not a single page was even scanned. The way it would detect the latter is by taking a snapshot of sc->nr_scanned at the beginning of the function and comparing it against the new sc->nr_scanned after the scan loop. But it would re-iterate without updating that snapshot, looping forever if sc->nr_scanned changed at least once since shrink_zone() was invoked. This is not the sole condition that would exit that loop, but it requires other processes to change the zone state, as the reclaimer that is stuck obviously can not anymore. This is only happening for higher-order allocations, where reclaim is run back to back with compaction. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Michal Hocko <mhocko@suse.cz> Tested-by: Kent Overstreet<kent.overstreet@gmail.com> Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f33261d7 |
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25-Jan-2011 |
David Rientjes <rientjes@google.com> |
mm: fix deferred congestion timeout if preferred zone is not allowed Before 0e093d99763e ("writeback: do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone"), preferred_zone was only used for NUMA statistics, to determine the zoneidx from which to allocate from given the type requested, and whether to utilize memory compaction. wait_iff_congested(), though, uses preferred_zone to determine if the congestion wait should be deferred because its dirty pages are backed by a congested bdi. This incorrectly defers the timeout and busy loops in the page allocator with various cond_resched() calls if preferred_zone is not allowed in the current context, usually consuming 100% of a cpu. This patch ensures preferred_zone is an allowed zone in the fastpath depending on whether current is constrained by its cpuset or nodes in its mempolicy (when the nodemask passed is non-NULL). This is correct since the fastpath allocation always passes ALLOC_CPUSET when trying to allocate memory. In the slowpath, this patch resets preferred_zone to the first zone of the allowed type when the allocation is not constrained by current's cpuset, i.e. it does not pass ALLOC_CPUSET. This patch also ensures preferred_zone is from the set of allowed nodes when called from within direct reclaim since allocations are always constrained by cpusets in this context (it is blockable). Both of these uses of cpuset_current_mems_allowed are protected by get_mems_allowed(). Signed-off-by: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3305de51 |
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20-Jan-2011 |
Jesper Juhl <jj@chaosbits.net> |
mm/vmscan.c: remove duplicate include of compaction.h Signed-off-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7a608572 |
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17-Jan-2011 |
Linus Torvalds <torvalds@linux-foundation.org> |
Revert "mm: batch activate_page() to reduce lock contention" This reverts commit 744ed1442757767ffede5008bb13e0805085902e. Chris Mason ended up chasing down some page allocation errors and pages stuck waiting on the IO scheduler, and was able to narrow it down to two commits: commit 744ed1442757 ("mm: batch activate_page() to reduce lock contention") and d8505dee1a87 ("mm: simplify code of swap.c"). This reverts the first of them. Reported-and-debugged-by: Chris Mason <chris.mason@oracle.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jens Axboe <jaxboe@fusionio.com> Cc: linux-mm <linux-mm@kvack.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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744ed144 |
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13-Jan-2011 |
Shaohua Li <shaohua.li@intel.com> |
mm: batch activate_page() to reduce lock contention The zone->lru_lock is heavily contented in workload where activate_page() is frequently used. We could do batch activate_page() to reduce the lock contention. The batched pages will be added into zone list when the pool is full or page reclaim is trying to drain them. For example, in a 4 socket 64 CPU system, create a sparse file and 64 processes, processes shared map to the file. Each process read access the whole file and then exit. The process exit will do unmap_vmas() and cause a lot of activate_page() call. In such workload, we saw about 58% total time reduction with below patch. Other workloads with a lot of activate_page also benefits a lot too. I tested some microbenchmarks: case-anon-cow-rand-mt 0.58% case-anon-cow-rand -3.30% case-anon-cow-seq-mt -0.51% case-anon-cow-seq -5.68% case-anon-r-rand-mt 0.23% case-anon-r-rand 0.81% case-anon-r-seq-mt -0.71% case-anon-r-seq -1.99% case-anon-rx-rand-mt 2.11% case-anon-rx-seq-mt 3.46% case-anon-w-rand-mt -0.03% case-anon-w-rand -0.50% case-anon-w-seq-mt -1.08% case-anon-w-seq -0.12% case-anon-wx-rand-mt -5.02% case-anon-wx-seq-mt -1.43% case-fork 1.65% case-fork-sleep -0.07% case-fork-withmem 1.39% case-hugetlb -0.59% case-lru-file-mmap-read-mt -0.54% case-lru-file-mmap-read 0.61% case-lru-file-mmap-read-rand -2.24% case-lru-file-readonce -0.64% case-lru-file-readtwice -11.69% case-lru-memcg -1.35% case-mmap-pread-rand-mt 1.88% case-mmap-pread-rand -15.26% case-mmap-pread-seq-mt 0.89% case-mmap-pread-seq -69.72% case-mmap-xread-rand-mt 0.71% case-mmap-xread-seq-mt 0.38% The most significent are: case-lru-file-readtwice -11.69% case-mmap-pread-rand -15.26% case-mmap-pread-seq -69.72% which use activate_page a lot. others are basically variations because each run has slightly difference. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9992af10 |
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13-Jan-2011 |
Rik van Riel <riel@redhat.com> |
thp: scale nr_rotated to balance memory pressure Make sure we scale up nr_rotated when we encounter a referenced transparent huge page. This ensures pageout scanning balance is not distorted when there are huge pages on the LRU. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2c888cfb |
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13-Jan-2011 |
Rik van Riel <riel@redhat.com> |
thp: fix anon memory statistics with transparent hugepages Count each transparent hugepage as HPAGE_PMD_NR pages in the LRU statistics, so the Active(anon) and Inactive(anon) statistics in /proc/meminfo are correct. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5a03b051 |
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13-Jan-2011 |
Andrea Arcangeli <aarcange@redhat.com> |
thp: use compaction in kswapd for GFP_ATOMIC order > 0 This takes advantage of memory compaction to properly generate pages of order > 0 if regular page reclaim fails and priority level becomes more severe and we don't reach the proper watermarks. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dc83edd9 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: kswapd: use the classzone idx that kswapd was using for sleeping_prematurely() When kswapd is woken up for a high-order allocation, it takes account of the highest usable zone by the caller (the classzone idx). During allocation, this index is used to select the lowmem_reserve[] that should be applied to the watermark calculation in zone_watermark_ok(). When balancing a node, kswapd considers the highest unbalanced zone to be the classzone index. This will always be at least be the callers classzone_idx and can be higher. However, sleeping_prematurely() always considers the lowest zone (e.g. ZONE_DMA) to be the classzone index. This means that sleeping_prematurely() can consider a zone to be balanced that is unusable by the allocation request that originally woke kswapd. This patch changes sleeping_prematurely() to use a classzone_idx matching the value it used in balance_pgdat(). Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
355b09c4 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: kswapd: treat zone->all_unreclaimable in sleeping_prematurely similar to balance_pgdat() After DEF_PRIORITY, balance_pgdat() considers all_unreclaimable zones to be balanced but sleeping_prematurely does not. This can force kswapd to stay awake longer than it should. This patch fixes it. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
4d40502e |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: kswapd: reset kswapd_max_order and classzone_idx after reading When kswapd wakes up, it reads its order and classzone from pgdat and calls balance_pgdat. While its awake, it potentially reclaimes at a high order and a low classzone index. This might have been a once-off that was not required by subsequent callers. However, because the pgdat values were not reset, they remain artifically high while balance_pgdat() is running and potentially kswapd enters a second unnecessary reclaim cycle. Reset the pgdat order and classzone index after reading. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0abdee2b |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: kswapd: use the order that kswapd was reclaiming at for sleeping_prematurely() Before kswapd goes to sleep, it uses sleeping_prematurely() to check if there was a race pushing a zone below its watermark. If the race happened, it stays awake. However, balance_pgdat() can decide to reclaim at order-0 if it decides that high-order reclaim is not working as expected. This information is not passed back to sleeping_prematurely(). The impact is that kswapd remains awake reclaiming pages long after it should have gone to sleep. This patch passes the adjusted order to sleeping_prematurely and uses the same logic as balance_pgdat to decide if it's ok to go to sleep. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1741c877 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: kswapd: keep kswapd awake for high-order allocations until a percentage of the node is balanced When reclaiming for high-orders, kswapd is responsible for balancing a node but it should not reclaim excessively. It avoids excessive reclaim by considering if any zone in a node is balanced then the node is balanced. In the cases where there are imbalanced zone sizes (e.g. ZONE_DMA with both ZONE_DMA32 and ZONE_NORMAL), kswapd can go to sleep prematurely as just one small zone was balanced. This alters the sleep logic of kswapd slightly. It counts the number of pages that make up the balanced zones. If the total number of balanced pages is more than a quarter of the zone, kswapd will go back to sleep. This should keep a node balanced without reclaiming an excessive number of pages. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
99504748 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: kswapd: stop high-order balancing when any suitable zone is balanced Simon Kirby reported the following problem We're seeing cases on a number of servers where cache never fully grows to use all available memory. Sometimes we see servers with 4 GB of memory that never seem to have less than 1.5 GB free, even with a constantly-active VM. In some cases, these servers also swap out while this happens, even though they are constantly reading the working set into memory. We have been seeing this happening for a long time; I don't think it's anything recent, and it still happens on 2.6.36. After some debugging work by Simon, Dave Hansen and others, the prevaling theory became that kswapd is reclaiming order-3 pages requested by SLUB too aggressive about it. There are two apparent problems here. On the target machine, there is a small Normal zone in comparison to DMA32. As kswapd tries to balance all zones, it would continually try reclaiming for Normal even though DMA32 was balanced enough for callers. The second problem is that sleeping_prematurely() does not use the same logic as balance_pgdat() when deciding whether to sleep or not. This keeps kswapd artifically awake. A number of tests were run and the figures from previous postings will look very different for a few reasons. One, the old figures were forcing my network card to use GFP_ATOMIC in attempt to replicate Simon's problem. Second, I previous specified slub_min_order=3 again in an attempt to reproduce Simon's problem. In this posting, I'm depending on Simon to say whether his problem is fixed or not and these figures are to show the impact to the ordinary cases. Finally, the "vmscan" figures are taken from /proc/vmstat instead of the tracepoints. There is less information but recording is less disruptive. The first test of relevance was postmark with a process running in the background reading a large amount of anonymous memory in blocks. The objective was to vaguely simulate what was happening on Simon's machine and it's memory intensive enough to have kswapd awake. POSTMARK traceonly kanyzone Transactions per second: 156.00 ( 0.00%) 153.00 (-1.96%) Data megabytes read per second: 21.51 ( 0.00%) 21.52 ( 0.05%) Data megabytes written per second: 29.28 ( 0.00%) 29.11 (-0.58%) Files created alone per second: 250.00 ( 0.00%) 416.00 (39.90%) Files create/transact per second: 79.00 ( 0.00%) 76.00 (-3.95%) Files deleted alone per second: 520.00 ( 0.00%) 420.00 (-23.81%) Files delete/transact per second: 79.00 ( 0.00%) 76.00 (-3.95%) MMTests Statistics: duration User/Sys Time Running Test (seconds) 16.58 17.4 Total Elapsed Time (seconds) 218.48 222.47 VMstat Reclaim Statistics: vmscan Direct reclaims 0 4 Direct reclaim pages scanned 0 203 Direct reclaim pages reclaimed 0 184 Kswapd pages scanned 326631 322018 Kswapd pages reclaimed 312632 309784 Kswapd low wmark quickly 1 4 Kswapd high wmark quickly 122 475 Kswapd skip congestion_wait 1 0 Pages activated 700040 705317 Pages deactivated 212113 203922 Pages written 9875 6363 Total pages scanned 326631 322221 Total pages reclaimed 312632 309968 %age total pages scanned/reclaimed 95.71% 96.20% %age total pages scanned/written 3.02% 1.97% proc vmstat: Faults Major Faults 300 254 Minor Faults 645183 660284 Page ins 493588 486704 Page outs 4960088 4986704 Swap ins 1230 661 Swap outs 9869 6355 Performance is mildly affected because kswapd is no longer doing as much work and the background memory consumer process is getting in the way. Note that kswapd scanned and reclaimed fewer pages as it's less aggressive and overall fewer pages were scanned and reclaimed. Swap in/out is particularly reduced again reflecting kswapd throwing out fewer pages. The slight performance impact is unfortunate here but it looks like a direct result of kswapd being less aggressive. As the bug report is about too many pages being freed by kswapd, it may have to be accepted for now. The second test is a streaming IO benchmark that was previously used by Johannes to show regressions in page reclaim. MICRO traceonly kanyzone User/Sys Time Running Test (seconds) 29.29 28.87 Total Elapsed Time (seconds) 492.18 488.79 VMstat Reclaim Statistics: vmscan Direct reclaims 2128 1460 Direct reclaim pages scanned 2284822 1496067 Direct reclaim pages reclaimed 148919 110937 Kswapd pages scanned 15450014 16202876 Kswapd pages reclaimed 8503697 8537897 Kswapd low wmark quickly 3100 3397 Kswapd high wmark quickly 1860 7243 Kswapd skip congestion_wait 708 801 Pages activated 9635 9573 Pages deactivated 1432 1271 Pages written 223 1130 Total pages scanned 17734836 17698943 Total pages reclaimed 8652616 8648834 %age total pages scanned/reclaimed 48.79% 48.87% %age total pages scanned/written 0.00% 0.01% proc vmstat: Faults Major Faults 165 221 Minor Faults 9655785 9656506 Page ins 3880 7228 Page outs 37692940 37480076 Swap ins 0 69 Swap outs 19 15 Again fewer pages are scanned and reclaimed as expected and this time the test completed faster. Note that kswapd is hitting its watermarks faster (low and high wmark quickly) which I expect is due to kswapd reclaiming fewer pages. I also ran fs-mark, iozone and sysbench but there is nothing interesting to report in the figures. Performance is not significantly changed and the reclaim statistics look reasonable. Tgis patch: When the allocator enters its slow path, kswapd is woken up to balance the node. It continues working until all zones within the node are balanced. For order-0 allocations, this makes perfect sense but for higher orders it can have unintended side-effects. If the zone sizes are imbalanced, kswapd may reclaim heavily within a smaller zone discarding an excessive number of pages. The user-visible behaviour is that kswapd is awake and reclaiming even though plenty of pages are free from a suitable zone. This patch alters the "balance" logic for high-order reclaim allowing kswapd to stop if any suitable zone becomes balanced to reduce the number of pages it reclaims from other zones. kswapd still tries to ensure that order-0 watermarks for all zones are met before sleeping. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f3a310bc |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: rename lumpy_mode to reclaim_mode With compaction being used instead of lumpy reclaim, the name lumpy_mode and associated variables is a bit misleading. Rename lumpy_mode to reclaim_mode which is a better fit. There is no functional change. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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77f1fe6b |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: migration: allow migration to operate asynchronously and avoid synchronous compaction in the faster path Migration synchronously waits for writeback if the initial passes fails. Callers of memory compaction do not necessarily want this behaviour if the caller is latency sensitive or expects that synchronous migration is not going to have a significantly better success rate. This patch adds a sync parameter to migrate_pages() allowing the caller to indicate if wait_on_page_writeback() is allowed within migration or not. For reclaim/compaction, try_to_compact_pages() is first called asynchronously, direct reclaim runs and then try_to_compact_pages() is called synchronously as there is a greater expectation that it'll succeed. [akpm@linux-foundation.org: build/merge fix] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3e7d3449 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaim Lumpy reclaim is disruptive. It reclaims a large number of pages and ignores the age of the pages it reclaims. This can incur significant stalls and potentially increase the number of major faults. Compaction has reached the point where it is considered reasonably stable (meaning it has passed a lot of testing) and is a potential candidate for displacing lumpy reclaim. This patch introduces an alternative to lumpy reclaim whe compaction is available called reclaim/compaction. The basic operation is very simple - instead of selecting a contiguous range of pages to reclaim, a number of order-0 pages are reclaimed and then compaction is later by either kswapd (compact_zone_order()) or direct compaction (__alloc_pages_direct_compact()). [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: use conventional task_struct naming] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ee64fc93 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmscan: convert lumpy_mode into a bitmask Currently lumpy_mode is an enum and determines if lumpy reclaim is off, syncronous or asyncronous. In preparation for using compaction instead of lumpy reclaim, this patch converts the flags into a bitmap. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f0bc0a60 |
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13-Jan-2011 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: factor out kswapd sleeping logic from kswapd() Currently, kswapd() has deep nesting and is slightly hard to read. Clean this up. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b44129b3 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: vmstat: use a single setter function and callback for adjusting percpu thresholds reduce_pgdat_percpu_threshold() and restore_pgdat_percpu_threshold() exist to adjust the per-cpu vmstat thresholds while kswapd is awake to avoid errors due to counter drift. The functions duplicate some code so this patch replaces them with a single set_pgdat_percpu_threshold() that takes a callback function to calculate the desired threshold as a parameter. [akpm@linux-foundation.org: readability tweak] [kosaki.motohiro@jp.fujitsu.com: set_pgdat_percpu_threshold(): don't use for_each_online_cpu] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Christoph Lameter <cl@linux.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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88f5acf8 |
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13-Jan-2011 |
Mel Gorman <mel@csn.ul.ie> |
mm: page allocator: adjust the per-cpu counter threshold when memory is low Commit aa45484 ("calculate a better estimate of NR_FREE_PAGES when memory is low") noted that watermarks were based on the vmstat NR_FREE_PAGES. To avoid synchronization overhead, these counters are maintained on a per-cpu basis and drained both periodically and when a threshold is above a threshold. On large CPU systems, the difference between the estimate and real value of NR_FREE_PAGES can be very high. The system can get into a case where pages are allocated far below the min watermark potentially causing livelock issues. The commit solved the problem by taking a better reading of NR_FREE_PAGES when memory was low. Unfortately, as reported by Shaohua Li this accurate reading can consume a large amount of CPU time on systems with many sockets due to cache line bouncing. This patch takes a different approach. For large machines where counter drift might be unsafe and while kswapd is awake, the per-cpu thresholds for the target pgdat are reduced to limit the level of drift to what should be a safe level. This incurs a performance penalty in heavy memory pressure by a factor that depends on the workload and the machine but the machine should function correctly without accidentally exhausting all memory on a node. There is an additional cost when kswapd wakes and sleeps but the event is not expected to be frequent - in Shaohua's test case, there was one recorded sleep and wake event at least. To ensure that kswapd wakes up, a safe version of zone_watermark_ok() is introduced that takes a more accurate reading of NR_FREE_PAGES when called from wakeup_kswapd, when deciding whether it is really safe to go back to sleep in sleeping_prematurely() and when deciding if a zone is really balanced or not in balance_pgdat(). We are still using an expensive function but limiting how often it is called. When the test case is reproduced, the time spent in the watermark functions is reduced. The following report is on the percentage of time spent cumulatively spent in the functions zone_nr_free_pages(), zone_watermark_ok(), __zone_watermark_ok(), zone_watermark_ok_safe(), zone_page_state_snapshot(), zone_page_state(). vanilla 11.6615% disable-threshold 0.2584% David said: : We had to pull aa454840 "mm: page allocator: calculate a better estimate : of NR_FREE_PAGES when memory is low and kswapd is awake" from 2.6.36 : internally because tests showed that it would cause the machine to stall : as the result of heavy kswapd activity. I merged it back with this fix as : it is pending in the -mm tree and it solves the issue we were seeing, so I : definitely think this should be pushed to -stable (and I would seriously : consider it for 2.6.37 inclusion even at this late date). Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reported-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Christoph Lameter <cl@linux.com> Tested-by: Nicolas Bareil <nico@chdir.org> Cc: David Rientjes <rientjes@google.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: <stable@kernel.org> [2.6.37.1, 2.6.36.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6072d13c |
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01-Dec-2010 |
Linus Torvalds <torvalds@linux-foundation.org> |
Call the filesystem back whenever a page is removed from the page cache NFS needs to be able to release objects that are stored in the page cache once the page itself is no longer visible from the page cache. This patch adds a callback to the address space operations that allows filesystems to perform page cleanups once the page has been removed from the page cache. Original patch by: Linus Torvalds <torvalds@linux-foundation.org> [trondmy: cover the cases of invalidate_inode_pages2() and truncate_inode_pages()] Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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1dce071e |
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11-Nov-2010 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: avoid setting zone congested if no page dirty nr_dirty and nr_congested are increased only when the page is dirty. So if all pages are clean, both them will be zero. In this case, we should not mark the zone congested. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2e30244a |
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26-Oct-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan,tmpfs: treat used once pages on tmpfs as used once When a page has PG_referenced, shrink_page_list() discards it only if it is not dirty. This rule works fine if the backing filesystem is a regular one. PG_dirty is a good signal that the page was used recently because the flusher threads clean pages periodically. In addition, page writeback is costlier than simple page discard. However, when a page is on tmpfs this heuristic doesn't work because flusher threads don't write back tmpfs pages. Consequently tmpfs pages always rotate around the lru twice at least and adds unnecessary lru churn. Simple tmpfs streaming io shouldn't cause large anonymous page swap-out. Remove this unncessary reclaim bonus of tmpfs pages. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0e093d99 |
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26-Oct-2010 |
Mel Gorman <mel@csn.ul.ie> |
writeback: do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone If congestion_wait() is called with no BDI congested, the caller will sleep for the full timeout and this may be an unnecessary sleep. This patch adds a wait_iff_congested() that checks congestion and only sleeps if a BDI is congested else, it calls cond_resched() to ensure the caller is not hogging the CPU longer than its quota but otherwise will not sleep. This is aimed at reducing some of the major desktop stalls reported during IO. For example, while kswapd is operating, it calls congestion_wait() but it could just have been reclaiming clean page cache pages with no congestion. Without this patch, it would sleep for a full timeout but after this patch, it'll just call schedule() if it has been on the CPU too long. Similar logic applies to direct reclaimers that are not making enough progress. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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08fc468f |
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26-Oct-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: isolate_lru_pages(): stop neighbour search if neighbour cannot be isolated isolate_lru_pages() does not just isolate LRU tail pages, but also isolates neighbour pages of the eviction page. The neighbour search does not stop even if neighbours cannot be isolated which is excessive as the lumpy reclaim will no longer result in a successful higher order allocation. This patch stops the PFN neighbour pages if an isolation fails and moves on to the next block. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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47185052 |
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26-Oct-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: remove dead code in shrink_inactive_list() After synchrounous lumpy reclaim, the page_list is guaranteed to not have active pages as page activation in shrink_page_list() disables lumpy reclaim. Remove the dead code. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7d3579e8 |
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26-Oct-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: narrow the scenarios in whcih lumpy reclaim uses synchrounous reclaim shrink_page_list() can decide to give up reclaiming a page under a number of conditions such as 1. trylock_page() failure 2. page is unevictable 3. zone reclaim and page is mapped 4. PageWriteback() is true 5. page is swapbacked and swap is full 6. add_to_swap() failure 7. page is dirty and gfpmask don't have GFP_IO, GFP_FS 8. page is pinned 9. IO queue is congested 10. pageout() start IO, but not finished With lumpy reclaim, failures result in entering synchronous lumpy reclaim but this can be unnecessary. In cases (2), (3), (5), (6), (7) and (8), there is no point retrying. This patch causes lumpy reclaim to abort when it is known it will fail. Case (9) is more interesting. current behavior is, 1. start shrink_page_list(async) 2. found queue_congested() 3. skip pageout write 4. still start shrink_page_list(sync) 5. wait on a lot of pages 6. again, found queue_congested() 7. give up pageout write again So, it's useless time wasting. However, just skipping page reclaim is also notgood as x86 allocating a huge page needs 512 pages for example. It can have more dirty pages than queue congestion threshold (~=128). After this patch, pageout() behaves as follows; - If order > PAGE_ALLOC_COSTLY_ORDER Ignore queue congestion always. - If order <= PAGE_ALLOC_COSTLY_ORDER skip write page and disable lumpy reclaim. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bc57e00f |
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26-Oct-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: synchronous lumpy reclaim should not call congestion_wait() congestion_wait() means "wait until queue congestion is cleared". However, synchronous lumpy reclaim does not need this congestion_wait() as shrink_page_list(PAGEOUT_IO_SYNC) uses wait_on_page_writeback() and it provides the necessary waiting. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e11da5b4 |
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26-Oct-2010 |
Mel Gorman <mel@csn.ul.ie> |
tracing, vmscan: add trace events for LRU list shrinking There have been numerous reports of stalls that pointed at the problem being somewhere in the VM. There are multiple roots to the problems which means dealing with any of the root problems in isolation is tricky to justify on their own and they would still need integration testing. This patch series puts together two different patch sets which in combination should tackle some of the root causes of latency problems being reported. Patch 1 adds a tracepoint for shrink_inactive_list. For this series, the most important results is being able to calculate the scanning/reclaim ratio as a measure of the amount of work being done by page reclaim. Patch 2 accounts for time spent in congestion_wait. Patches 3-6 were originally developed by Kosaki Motohiro but reworked for this series. It has been noted that lumpy reclaim is far too aggressive and trashes the system somewhat. As SLUB uses high-order allocations, a large cost incurred by lumpy reclaim will be noticeable. It was also reported during transparent hugepage support testing that lumpy reclaim was trashing the system and these patches should mitigate that problem without disabling lumpy reclaim. Patch 7 adds wait_iff_congested() and replaces some callers of congestion_wait(). wait_iff_congested() only sleeps if there is a BDI that is currently congested. Patch 8 notes that any BDI being congested is not necessarily a problem because there could be multiple BDIs of varying speeds and numberous zones. It attempts to track when a zone being reclaimed contains many pages backed by a congested BDI and if so, reclaimers wait on the congestion queue. I ran a number of tests with monitoring on X86, X86-64 and PPC64. Each machine had 3G of RAM and the CPUs were X86: Intel P4 2-core X86-64: AMD Phenom 4-core PPC64: PPC970MP Each used a single disk and the onboard IO controller. Dirty ratio was left at 20. I'm just going to report for X86-64 and PPC64 in a vague attempt to keep this report short. Four kernels were tested each based on v2.6.36-rc4 traceonly-v2r2: Patches 1 and 2 to instrument vmscan reclaims and congestion_wait lowlumpy-v2r3: Patches 1-6 to test if lumpy reclaim is better waitcongest-v2r3: Patches 1-7 to only wait on congestion waitwriteback-v2r4: Patches 1-8 to detect when a zone is congested nocongest-v1r5: Patches 1-3 for testing wait_iff_congestion nodirect-v1r5: Patches 1-10 to disable filesystem writeback for better IO The tests run were as follows kernbench compile-based benchmark. Smoke test performance sysbench OLTP read-only benchmark. Will be re-run in the future as read-write micro-mapped-file-stream This is a micro-benchmark from Johannes Weiner that accesses a large sparse-file through mmap(). It was configured to run in only single-CPU mode but can be indicative of how well page reclaim identifies suitable pages. stress-highalloc Tries to allocate huge pages under heavy load. kernbench, iozone and sysbench did not report any performance regression on any machine. sysbench did pressure the system lightly and there was reclaim activity but there were no difference of major interest between the kernels. X86-64 micro-mapped-file-stream traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3 waitwriteback-v2r4 pgalloc_dma 1639.00 ( 0.00%) 667.00 (-145.73%) 1167.00 ( -40.45%) 578.00 (-183.56%) pgalloc_dma32 2842410.00 ( 0.00%) 2842626.00 ( 0.01%) 2843043.00 ( 0.02%) 2843014.00 ( 0.02%) pgalloc_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pgsteal_dma 729.00 ( 0.00%) 85.00 (-757.65%) 609.00 ( -19.70%) 125.00 (-483.20%) pgsteal_dma32 2338721.00 ( 0.00%) 2447354.00 ( 4.44%) 2429536.00 ( 3.74%) 2436772.00 ( 4.02%) pgsteal_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pgscan_kswapd_dma 1469.00 ( 0.00%) 532.00 (-176.13%) 1078.00 ( -36.27%) 220.00 (-567.73%) pgscan_kswapd_dma32 4597713.00 ( 0.00%) 4503597.00 ( -2.09%) 4295673.00 ( -7.03%) 3891686.00 ( -18.14%) pgscan_kswapd_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pgscan_direct_dma 71.00 ( 0.00%) 134.00 ( 47.01%) 243.00 ( 70.78%) 352.00 ( 79.83%) pgscan_direct_dma32 305820.00 ( 0.00%) 280204.00 ( -9.14%) 600518.00 ( 49.07%) 957485.00 ( 68.06%) pgscan_direct_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pageoutrun 16296.00 ( 0.00%) 21254.00 ( 23.33%) 18447.00 ( 11.66%) 20067.00 ( 18.79%) allocstall 443.00 ( 0.00%) 273.00 ( -62.27%) 513.00 ( 13.65%) 1568.00 ( 71.75%) These are based on the raw figures taken from /proc/vmstat. It's a rough measure of reclaim activity. Note that allocstall counts are higher because we are entering direct reclaim more often as a result of not sleeping in congestion. In itself, it's not necessarily a bad thing. It's easier to get a view of what happened from the vmscan tracepoint report. FTrace Reclaim Statistics: vmscan traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3 waitwriteback-v2r4 Direct reclaims 443 273 513 1568 Direct reclaim pages scanned 305968 280402 600825 957933 Direct reclaim pages reclaimed 43503 19005 30327 117191 Direct reclaim write file async I/O 0 0 0 0 Direct reclaim write anon async I/O 0 3 4 12 Direct reclaim write file sync I/O 0 0 0 0 Direct reclaim write anon sync I/O 0 0 0 0 Wake kswapd requests 187649 132338 191695 267701 Kswapd wakeups 3 1 4 1 Kswapd pages scanned 4599269 4454162 4296815 3891906 Kswapd pages reclaimed 2295947 2428434 2399818 2319706 Kswapd reclaim write file async I/O 1 0 1 1 Kswapd reclaim write anon async I/O 59 187 41 222 Kswapd reclaim write file sync I/O 0 0 0 0 Kswapd reclaim write anon sync I/O 0 0 0 0 Time stalled direct reclaim (seconds) 4.34 2.52 6.63 2.96 Time kswapd awake (seconds) 11.15 10.25 11.01 10.19 Total pages scanned 4905237 4734564 4897640 4849839 Total pages reclaimed 2339450 2447439 2430145 2436897 %age total pages scanned/reclaimed 47.69% 51.69% 49.62% 50.25% %age total pages scanned/written 0.00% 0.00% 0.00% 0.00% %age file pages scanned/written 0.00% 0.00% 0.00% 0.00% Percentage Time Spent Direct Reclaim 29.23% 19.02% 38.48% 20.25% Percentage Time kswapd Awake 78.58% 78.85% 76.83% 79.86% What is interesting here for nocongest in particular is that while direct reclaim scans more pages, the overall number of pages scanned remains the same and the ratio of pages scanned to pages reclaimed is more or less the same. In other words, while we are sleeping less, reclaim is not doing more work and as direct reclaim and kswapd is awake for less time, it would appear to be doing less work. FTrace Reclaim Statistics: congestion_wait Direct number congest waited 87 196 64 0 Direct time congest waited 4604ms 4732ms 5420ms 0ms Direct full congest waited 72 145 53 0 Direct number conditional waited 0 0 324 1315 Direct time conditional waited 0ms 0ms 0ms 0ms Direct full conditional waited 0 0 0 0 KSwapd number congest waited 20 10 15 7 KSwapd time congest waited 1264ms 536ms 884ms 284ms KSwapd full congest waited 10 4 6 2 KSwapd number conditional waited 0 0 0 0 KSwapd time conditional waited 0ms 0ms 0ms 0ms KSwapd full conditional waited 0 0 0 0 The vanilla kernel spent 8 seconds asleep in direct reclaim and no time at all asleep with the patches. MMTests Statistics: duration User/Sys Time Running Test (seconds) 10.51 10.73 10.6 11.66 Total Elapsed Time (seconds) 14.19 13.00 14.33 12.76 Overall, the tests completed faster. It is interesting to note that backing off further when a zone is congested and not just a BDI was more efficient overall. PPC64 micro-mapped-file-stream pgalloc_dma 3024660.00 ( 0.00%) 3027185.00 ( 0.08%) 3025845.00 ( 0.04%) 3026281.00 ( 0.05%) pgalloc_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pgsteal_dma 2508073.00 ( 0.00%) 2565351.00 ( 2.23%) 2463577.00 ( -1.81%) 2532263.00 ( 0.96%) pgsteal_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pgscan_kswapd_dma 4601307.00 ( 0.00%) 4128076.00 ( -11.46%) 3912317.00 ( -17.61%) 3377165.00 ( -36.25%) pgscan_kswapd_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pgscan_direct_dma 629825.00 ( 0.00%) 971622.00 ( 35.18%) 1063938.00 ( 40.80%) 1711935.00 ( 63.21%) pgscan_direct_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) pageoutrun 27776.00 ( 0.00%) 20458.00 ( -35.77%) 18763.00 ( -48.04%) 18157.00 ( -52.98%) allocstall 977.00 ( 0.00%) 2751.00 ( 64.49%) 2098.00 ( 53.43%) 5136.00 ( 80.98%) Similar trends to x86-64. allocstalls are up but it's not necessarily bad. FTrace Reclaim Statistics: vmscan Direct reclaims 977 2709 2098 5136 Direct reclaim pages scanned 629825 963814 1063938 1711935 Direct reclaim pages reclaimed 75550 242538 150904 387647 Direct reclaim write file async I/O 0 0 0 2 Direct reclaim write anon async I/O 0 10 0 4 Direct reclaim write file sync I/O 0 0 0 0 Direct reclaim write anon sync I/O 0 0 0 0 Wake kswapd requests 392119 1201712 571935 571921 Kswapd wakeups 3 2 3 3 Kswapd pages scanned 4601307 4128076 3912317 3377165 Kswapd pages reclaimed 2432523 2318797 2312673 2144616 Kswapd reclaim write file async I/O 20 1 1 1 Kswapd reclaim write anon async I/O 57 132 11 121 Kswapd reclaim write file sync I/O 0 0 0 0 Kswapd reclaim write anon sync I/O 0 0 0 0 Time stalled direct reclaim (seconds) 6.19 7.30 13.04 10.88 Time kswapd awake (seconds) 21.73 26.51 25.55 23.90 Total pages scanned 5231132 5091890 4976255 5089100 Total pages reclaimed 2508073 2561335 2463577 2532263 %age total pages scanned/reclaimed 47.95% 50.30% 49.51% 49.76% %age total pages scanned/written 0.00% 0.00% 0.00% 0.00% %age file pages scanned/written 0.00% 0.00% 0.00% 0.00% Percentage Time Spent Direct Reclaim 18.89% 20.65% 32.65% 27.65% Percentage Time kswapd Awake 72.39% 80.68% 78.21% 77.40% Again, a similar trend that the congestion_wait changes mean that direct reclaim scans more pages but the overall number of pages scanned while slightly reduced, are very similar. The ratio of scanning/reclaimed remains roughly similar. The downside is that kswapd and direct reclaim was awake longer and for a larger percentage of the overall workload. It's possible there were big differences in the amount of time spent reclaiming slab pages between the different kernels which is plausible considering that the micro tests runs after fsmark and sysbench. Trace Reclaim Statistics: congestion_wait Direct number congest waited 845 1312 104 0 Direct time congest waited 19416ms 26560ms 7544ms 0ms Direct full congest waited 745 1105 72 0 Direct number conditional waited 0 0 1322 2935 Direct time conditional waited 0ms 0ms 12ms 312ms Direct full conditional waited 0 0 0 3 KSwapd number congest waited 39 102 75 63 KSwapd time congest waited 2484ms 6760ms 5756ms 3716ms KSwapd full congest waited 20 48 46 25 KSwapd number conditional waited 0 0 0 0 KSwapd time conditional waited 0ms 0ms 0ms 0ms KSwapd full conditional waited 0 0 0 0 The vanilla kernel spent 20 seconds asleep in direct reclaim and only 312ms asleep with the patches. The time kswapd spent congest waited was also reduced by a large factor. MMTests Statistics: duration ser/Sys Time Running Test (seconds) 26.58 28.05 26.9 28.47 Total Elapsed Time (seconds) 30.02 32.86 32.67 30.88 With all patches applies, the completion times are very similar. X86-64 STRESS-HIGHALLOC traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4 Pass 1 82.00 ( 0.00%) 84.00 ( 2.00%) 85.00 ( 3.00%) 85.00 ( 3.00%) Pass 2 90.00 ( 0.00%) 87.00 (-3.00%) 88.00 (-2.00%) 89.00 (-1.00%) At Rest 92.00 ( 0.00%) 90.00 (-2.00%) 90.00 (-2.00%) 91.00 (-1.00%) Success figures across the board are broadly similar. traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4 Direct reclaims 1045 944 886 887 Direct reclaim pages scanned 135091 119604 109382 101019 Direct reclaim pages reclaimed 88599 47535 47863 46671 Direct reclaim write file async I/O 494 283 465 280 Direct reclaim write anon async I/O 29357 13710 16656 13462 Direct reclaim write file sync I/O 154 2 2 3 Direct reclaim write anon sync I/O 14594 571 509 561 Wake kswapd requests 7491 933 872 892 Kswapd wakeups 814 778 731 780 Kswapd pages scanned 7290822 15341158 11916436 13703442 Kswapd pages reclaimed 3587336 3142496 3094392 3187151 Kswapd reclaim write file async I/O 91975 32317 28022 29628 Kswapd reclaim write anon async I/O 1992022 789307 829745 849769 Kswapd reclaim write file sync I/O 0 0 0 0 Kswapd reclaim write anon sync I/O 0 0 0 0 Time stalled direct reclaim (seconds) 4588.93 2467.16 2495.41 2547.07 Time kswapd awake (seconds) 2497.66 1020.16 1098.06 1176.82 Total pages scanned 7425913 15460762 12025818 13804461 Total pages reclaimed 3675935 3190031 3142255 3233822 %age total pages scanned/reclaimed 49.50% 20.63% 26.13% 23.43% %age total pages scanned/written 28.66% 5.41% 7.28% 6.47% %age file pages scanned/written 1.25% 0.21% 0.24% 0.22% Percentage Time Spent Direct Reclaim 57.33% 42.15% 42.41% 42.99% Percentage Time kswapd Awake 43.56% 27.87% 29.76% 31.25% Scanned/reclaimed ratios again look good with big improvements in efficiency. The Scanned/written ratios also look much improved. With a better scanned/written ration, there is an expectation that IO would be more efficient and indeed, the time spent in direct reclaim is much reduced by the full series and kswapd spends a little less time awake. Overall, indications here are that allocations were happening much faster and this can be seen with a graph of the latency figures as the allocations were taking place http://www.csn.ul.ie/~mel/postings/vmscanreduce-20101509/highalloc-interlatency-hydra-mean.ps FTrace Reclaim Statistics: congestion_wait Direct number congest waited 1333 204 169 4 Direct time congest waited 78896ms 8288ms 7260ms 200ms Direct full congest waited 756 92 69 2 Direct number conditional waited 0 0 26 186 Direct time conditional waited 0ms 0ms 0ms 2504ms Direct full conditional waited 0 0 0 25 KSwapd number congest waited 4 395 227 282 KSwapd time congest waited 384ms 25136ms 10508ms 18380ms KSwapd full congest waited 3 232 98 176 KSwapd number conditional waited 0 0 0 0 KSwapd time conditional waited 0ms 0ms 0ms 0ms KSwapd full conditional waited 0 0 0 0 KSwapd full conditional waited 318 0 312 9 Overall, the time spent speeping is reduced. kswapd is still hitting congestion_wait() but that is because there are callers remaining where it wasn't clear in advance if they should be changed to wait_iff_congested() or not. Overall the sleep imes are reduced though - from 79ish seconds to about 19. MMTests Statistics: duration User/Sys Time Running Test (seconds) 3415.43 3386.65 3388.39 3377.5 Total Elapsed Time (seconds) 5733.48 3660.33 3689.41 3765.39 With the full series, the time to complete the tests are reduced by 30% PPC64 STRESS-HIGHALLOC traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4 Pass 1 17.00 ( 0.00%) 34.00 (17.00%) 38.00 (21.00%) 43.00 (26.00%) Pass 2 25.00 ( 0.00%) 37.00 (12.00%) 42.00 (17.00%) 46.00 (21.00%) At Rest 49.00 ( 0.00%) 43.00 (-6.00%) 45.00 (-4.00%) 51.00 ( 2.00%) Success rates there are *way* up particularly considering that the 16MB huge pages on PPC64 mean that it's always much harder to allocate them. FTrace Reclaim Statistics: vmscan stress-highalloc stress-highalloc stress-highalloc stress-highalloc traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4 Direct reclaims 499 505 564 509 Direct reclaim pages scanned 223478 41898 51818 45605 Direct reclaim pages reclaimed 137730 21148 27161 23455 Direct reclaim write file async I/O 399 136 162 136 Direct reclaim write anon async I/O 46977 2865 4686 3998 Direct reclaim write file sync I/O 29 0 1 3 Direct reclaim write anon sync I/O 31023 159 237 239 Wake kswapd requests 420 351 360 326 Kswapd wakeups 185 294 249 277 Kswapd pages scanned 15703488 16392500 17821724 17598737 Kswapd pages reclaimed 5808466 2908858 3139386 3145435 Kswapd reclaim write file async I/O 159938 18400 18717 13473 Kswapd reclaim write anon async I/O 3467554 228957 322799 234278 Kswapd reclaim write file sync I/O 0 0 0 0 Kswapd reclaim write anon sync I/O 0 0 0 0 Time stalled direct reclaim (seconds) 9665.35 1707.81 2374.32 1871.23 Time kswapd awake (seconds) 9401.21 1367.86 1951.75 1328.88 Total pages scanned 15926966 16434398 17873542 17644342 Total pages reclaimed 5946196 2930006 3166547 3168890 %age total pages scanned/reclaimed 37.33% 17.83% 17.72% 17.96% %age total pages scanned/written 23.27% 1.52% 1.94% 1.43% %age file pages scanned/written 1.01% 0.11% 0.11% 0.08% Percentage Time Spent Direct Reclaim 44.55% 35.10% 41.42% 36.91% Percentage Time kswapd Awake 86.71% 43.58% 52.67% 41.14% While the scanning rates are slightly up, the scanned/reclaimed and scanned/written figures are much improved. The time spent in direct reclaim and with kswapd are massively reduced, mostly by the lowlumpy patches. FTrace Reclaim Statistics: congestion_wait Direct number congest waited 725 303 126 3 Direct time congest waited 45524ms 9180ms 5936ms 300ms Direct full congest waited 487 190 52 3 Direct number conditional waited 0 0 200 301 Direct time conditional waited 0ms 0ms 0ms 1904ms Direct full conditional waited 0 0 0 19 KSwapd number congest waited 0 2 23 4 KSwapd time congest waited 0ms 200ms 420ms 404ms KSwapd full congest waited 0 2 2 4 KSwapd number conditional waited 0 0 0 0 KSwapd time conditional waited 0ms 0ms 0ms 0ms KSwapd full conditional waited 0 0 0 0 Not as dramatic a story here but the time spent asleep is reduced and we can still see what wait_iff_congested is going to sleep when necessary. MMTests Statistics: duration User/Sys Time Running Test (seconds) 12028.09 3157.17 3357.79 3199.16 Total Elapsed Time (seconds) 10842.07 3138.72 3705.54 3229.85 The time to complete this test goes way down. With the full series, we are allocating over twice the number of huge pages in 30% of the time and there is a corresponding impact on the allocation latency graph available at. http://www.csn.ul.ie/~mel/postings/vmscanreduce-20101509/highalloc-interlatency-powyah-mean.ps This patch: Add a trace event for shrink_inactive_list() and updates the sample postprocessing script appropriately. It can be used to determine how many pages were reclaimed and for non-lumpy reclaim where exactly the pages were reclaimed from. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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66d9a986 |
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26-Oct-2010 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: delete dead code `priority' cannot be negative here. And the comment is obsolete. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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74e3f3c3 |
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26-Oct-2010 |
Minchan Kim <minchan.kim@gmail.com> |
vmscan: prevent background aging of anon page in no swap system Ying Han reported that backing aging of anon pages in no swap system causes unnecessary TLB flush. When I sent a patch(69c8548175), I wanted this patch but Rik pointed out and allowed aging of anon pages to give a chance to promote from inactive to active LRU. It has a two problem. 1) non-swap system Never make sense to age anon pages. 2) swap configured but still doesn't swapon It doesn't make sense to age anon pages until swap-on time. But it's arguable. If we have aged anon pages by swapon, VM have moved anon pages from active to inactive. And in the time swapon by admin, the VM can't reclaim hot pages so we can protect hot pages swapout. But let's think about it. When does swap-on happen? It depends on admin. we can't expect it. Nonetheless, we have done aging of anon pages to protect hot pages swapout. It means we lost run time overhead when below high watermark but gain hot page swap-[in/out] overhead when VM decide swapout. Is it true? Let's think more detail. We don't promote anon pages in case of non-swap system. So even though VM does aging of anon pages, the pages would be in inactive LRU for a long time. It means many of pages in there would mark access bit again. So access bit hot/code separation would be pointless. This patch prevents unnecessary anon pages demotion in not-yet-swapon and non-configured swap system. Even, in non-configuared swap system inactive_anon_is_low can be compiled out. It could make side effect that hot anon pages could swap out when admin does swap on. But I think sooner or later it would be steady state. So it's not a big problem. We could lose someting but gain more thing(TLB flush and unnecessary function call to demote anon pages). Signed-off-by: Ying Han <yinghan@google.com> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e4455abb |
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26-Oct-2010 |
Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com> |
mm: only build per-node scan_unevictable functions when NUMA is enabled Non-NUMA systems do never create these files anyway, since they are only created by driver subsystem when NUMA is configured. [akpm@linux-foundation.org: cleanup] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1b430bee |
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26-Oct-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: remove nonblocking/encountered_congestion references This removes more dead code that was somehow missed by commit 0d99519efef (writeback: remove unused nonblocking and congestion checks). There are no behavior change except for the removal of two entries from one of the ext4 tracing interface. The nonblocking checks in ->writepages are no longer used because the flusher now prefer to block on get_request_wait() than to skip inodes on IO congestion. The latter will lead to more seeky IO. The nonblocking checks in ->writepage are no longer used because it's redundant with the WB_SYNC_NONE check. We no long set ->nonblocking in VM page out and page migration, because a) it's effectively redundant with WB_SYNC_NONE in current code b) it's old semantic of "Don't get stuck on request queues" is mis-behavior: that would skip some dirty inodes on congestion and page out others, which is unfair in terms of LRU age. Inspired by Christoph Hellwig. Thanks! Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: David Howells <dhowells@redhat.com> Cc: Sage Weil <sage@newdream.net> Cc: Steve French <sfrench@samba.org> Cc: Chris Mason <chris.mason@oracle.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d1908362 |
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22-Sep-2010 |
Minchan Kim <minchan.kim@gmail.com> |
vmscan: check all_unreclaimable in direct reclaim path M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his 32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771). Also he bisected the regression to commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Date: Fri Jun 4 14:15:05 2010 -0700 vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure At first impression, this seemed very strange because the above commit only chenged function return value and hibernate_preallocate_memory() ignore return value of shrink_all_memory(). But it's related. Now, page allocation from hibernation code may enter infinite loop if the system has highmem. The reasons are that vmscan don't care enough OOM case when oom_killer_disabled. The problem sequence is following as. 1. hibernation 2. oom_disable 3. alloc_pages 4. do_try_to_free_pages if (scanning_global_lru(sc) && !all_unreclaimable) return 1; If kswapd is not freozen, it would set zone->all_unreclaimable to 1 and then shrink_zones maybe return true(ie, all_unreclaimable is true). So at last, alloc_pages could go to _nopage_. If it is, it should have no problem. This patch adds all_unreclaimable check to protect in direct reclaim path, too. It can care of hibernation OOM case and help bailout all_unreclaimable case slightly. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reported-by: M. Vefa Bicakci <bicave@superonline.com> Reported-by: <caiqian@redhat.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: <caiqian@redhat.com> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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415b54e3 |
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17-Aug-2010 |
Nikanth Karthikesan <knikanth@suse.de> |
Fix typo s/contenious/continuous in comment Fix typo s/contenious/continuous in comment. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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00918b6a |
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10-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: remove nid and zid argument from mem_cgroup_soft_limit_reclaim() mem_cgroup_soft_limit_reclaim() has zone, nid and zid argument. but nid and zid can be calculated from zone. So remove it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Nishimura Daisuke <d-nishimura@mtf.biglobe.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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14fec796 |
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10-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: mem_cgroup_shrink_node_zone() doesn't need sc.nodemask Currently mem_cgroup_shrink_node_zone() call shrink_zone() directly. thus it doesn't need to initialize sc.nodemask because shrink_zone() doesn't use it at all. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Nishimura Daisuke <d-nishimura@mtf.biglobe.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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da280d63 |
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10-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: kill unnecessary initialization in mem_cgroup_shrink_node_zone() sc.nr_reclaimed and sc.nr_scanned have already been initialized few lines above "struct scan_control sc = {}" statement. So, This patch remove this unnecessary code. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Nishimura Daisuke <d-nishimura@mtf.biglobe.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b8f5c566 |
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10-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: sc.nr_to_reclaim should be initialized Currently, mem_cgroup_shrink_node_zone() initialize sc.nr_to_reclaim as 0. It mean shrink_zone() only scan 32 pages and immediately return even if it doesn't reclaim any pages. This patch fixes it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Nishimura Daisuke <d-nishimura@mtf.biglobe.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e31f3698 |
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09-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: raise the bar to PAGEOUT_IO_SYNC stalls Fix "system goes unresponsive under memory pressure and lots of dirty/writeback pages" bug. http://lkml.org/lkml/2010/4/4/86 In the above thread, Andreas Mohr described that Invoking any command locked up for minutes (note that I'm talking about attempted additional I/O to the _other_, _unaffected_ main system HDD - such as loading some shell binaries -, NOT the external SSD18M!!). This happens when the two conditions are both meet: - under memory pressure - writing heavily to a slow device OOM also happens in Andreas' system. The OOM trace shows that 3 processes are stuck in wait_on_page_writeback() in the direct reclaim path. One in do_fork() and the other two in unix_stream_sendmsg(). They are blocked on this condition: (sc->order && priority < DEF_PRIORITY - 2) which was introduced in commit 78dc583d (vmscan: low order lumpy reclaim also should use PAGEOUT_IO_SYNC) one year ago. That condition may be too permissive. In Andreas' case, 512MB/1024 = 512KB. If the direct reclaim for the order-1 fork() allocation runs into a range of 512KB hard-to-reclaim LRU pages, it will be stalled. It's a severe problem in three ways. Firstly, it can easily happen in daily desktop usage. vmscan priority can easily go below (DEF_PRIORITY - 2) on _local_ memory pressure. Even if the system has 50% globally reclaimable pages, it still has good opportunity to have 0.1% sized hard-to-reclaim ranges. For example, a simple dd can easily create a big range (up to 20%) of dirty pages in the LRU lists. And order-1 to order-3 allocations are more than common with SLUB. Try "grep -v '1 :' /proc/slabinfo" to get the list of high order slab caches. For example, the order-1 radix_tree_node slab cache may stall applications at swap-in time; the order-3 inode cache on most filesystems may stall applications when trying to read some file; the order-2 proc_inode_cache may stall applications when trying to open a /proc file. Secondly, once triggered, it will stall unrelated processes (not doing IO at all) in the system. This "one slow USB device stalls the whole system" avalanching effect is very bad. Thirdly, once stalled, the stall time could be intolerable long for the users. When there are 20MB queued writeback pages and USB 1.1 is writing them in 1MB/s, wait_on_page_writeback() will stuck for up to 20 seconds. Not to mention it may be called multiple times. So raise the bar to only enable PAGEOUT_IO_SYNC when priority goes below DEF_PRIORITY/3, or 6.25% LRU size. As the default dirty throttle ratio is 20%, it will hardly be triggered by pure dirty pages. We'd better treat PAGEOUT_IO_SYNC as some last resort workaround -- its stall time is so uncomfortably long (easily goes beyond 1s). The bar is only raised for (order < PAGE_ALLOC_COSTLY_ORDER) allocations, which are easy to satisfy in 1TB memory boxes. So, although 6.25% of memory could be an awful lot of pages to scan on a system with 1TB of memory, it won't really have to busy scan that much. Andreas tested an older version of this patch and reported that it mostly fixed his problem. Mel Gorman helped improve it and KOSAKI Motohiro will fix it further in the next patch. Reported-by: Andreas Mohr <andi@lisas.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bdce6d9e |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg, vmscan: add memcg reclaim tracepoint Memcg also need to trace reclaim progress as direct reclaim. This patch add it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4dc4b3d9 |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: shrink_slab() requires the number of lru_pages, not the page order Presently shrink_slab() has the following scanning equation. lru_scanned max_pass basic_scan_objects = 4 x ------------- x ----------------------------- lru_pages shrinker->seeks (default:2) scan_objects = min(basic_scan_objects, max_pass * 2) If we pass very small value as lru_pages instead real number of lru pages, shrink_slab() drop much objects rather than necessary. And now, __zone_reclaim() pass 'order' as lru_pages by mistake. That produces a bad result. For example, if we receive very low memory pressure (scan = 32, order = 0), shrink_slab() via zone_reclaim() always drop _all_ icache/dcache objects. (see above equation, very small lru_pages make very big scan_objects result). This patch fixes it. [akpm@linux-foundation.org: fix layout, typos] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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58c37f6e |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: protect reading of reclaim_stat with lru_lock Rik van Riel pointed out reading reclaim_stat should be protected lru_lock, otherwise vmscan might sweep 2x much pages. This fault was introduced by commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db Author: Rik van Riel <riel@redhat.com> Date: Sat Oct 18 20:26:32 2008 -0700 vmscan: split LRU lists into anon & file sets Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
15748048 |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: avoid subtraction of unsigned types 'slab_reclaimable' and 'nr_pages' are unsigned. Subtraction is unsafe because negative results would be misinterpreted. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1489fa14 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: update isolated page counters outside of main path in shrink_inactive_list() When shrink_inactive_list() isolates pages, it updates a number of counters using temporary variables to gather them. These consume stack and it's in the main path that calls ->writepage(). This patch moves the accounting updates outside of the main path to reduce stack usage. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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abe4c3b5 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: set up pagevec as late as possible in shrink_page_list() shrink_page_list() sets up a pagevec to release pages as according as they are free. It uses significant amounts of stack on the pagevec. This patch adds pages to be freed via pagevec to a linked list which is then freed en-masse at the end. This avoids using stack in the main path that potentially calls writepage(). Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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66635629 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: set up pagevec as late as possible in shrink_inactive_list() shrink_inactive_list() sets up a pagevec to release unfreeable pages. It uses significant amounts of stack doing this. This patch splits shrink_inactive_list() to take the stack usage out of the main path so that callers to writepage() do not contain an unused pagevec on the stack. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d4debc66 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: remove unnecessary temporary vars in do_try_to_free_pages Remove temporary variable that is only used once and does not help clarify code. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e247dbce |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: simplify shrink_inactive_list() Now, max_scan of shrink_inactive_list() is always passed less than SWAP_CLUSTER_MAX. then, we can remove scanning pages loop in it. This patch also help stack diet. detail - remove "while (nr_scanned < max_scan)" loop - remove nr_freed (now, we use nr_reclaimed directly) - remove nr_scan (now, we use nr_scanned directly) - rename max_scan to nr_to_scan - pass nr_to_scan into isolate_pages() directly instead using SWAP_CLUSTER_MAX [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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25edde03 |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: kill prev_priority completely Since 2.6.28 zone->prev_priority is unused. Then it can be removed safely. It reduce stack usage slightly. Now I have to say that I'm sorry. 2 years ago, I thought prev_priority can be integrate again, it's useful. but four (or more) times trying haven't got good performance number. Thus I give up such approach. The rest of this changelog is notes on prev_priority and why it existed in the first place and why it might be not necessary any more. This information is based heavily on discussions between Andrew Morton, Rik van Riel and Kosaki Motohiro who is heavily quotes from. Historically prev_priority was important because it determined when the VM would start unmapping PTE pages. i.e. there are no balances of note within the VM, Anon vs File and Mapped vs Unmapped. Without prev_priority, there is a potential risk of unnecessarily increasing minor faults as a large amount of read activity of use-once pages could push mapped pages to the end of the LRU and get unmapped. There is no proof this is still a problem but currently it is not considered to be. Active files are not deactivated if the active file list is smaller than the inactive list reducing the liklihood that file-mapped pages are being pushed off the LRU and referenced executable pages are kept on the active list to avoid them getting pushed out by read activity. Even if it is a problem, prev_priority prev_priority wouldn't works nowadays. First of all, current vmscan still a lot of UP centric code. it expose some weakness on some dozens CPUs machine. I think we need more and more improvement. The problem is, current vmscan mix up per-system-pressure, per-zone-pressure and per-task-pressure a bit. example, prev_priority try to boost priority to other concurrent priority. but if the another task have mempolicy restriction, it is unnecessary, but also makes wrong big latency and exceeding reclaim. per-task based priority + prev_priority adjustment make the emulation of per-system pressure. but it have two issue 1) too rough and brutal emulation 2) we need per-zone pressure, not per-system. Another example, currently DEF_PRIORITY is 12. it mean the lru rotate about 2 cycle (1/4096 + 1/2048 + 1/1024 + .. + 1) before invoking OOM-Killer. but if 10,0000 thrreads enter DEF_PRIORITY reclaim at the same time, the system have higher memory pressure than priority==0 (1/4096*10,000 > 2). prev_priority can't solve such multithreads workload issue. In other word, prev_priority concept assume the sysmtem don't have lots threads." Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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755f0225 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: tracing: add trace event when a page is written Add a trace event for when page reclaim queues a page for IO and records whether it is synchronous or asynchronous. Excessive synchronous IO for a process can result in noticeable stalls during direct reclaim. Excessive IO from page reclaim may indicate that the system is seriously under provisioned for the amount of dirty pages that exist. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Larry Woodman <lwoodman@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a8a94d15 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: tracing: add trace events for LRU page isolation Add an event for when pages are isolated en-masse from the LRU lists. This event augments the information available on LRU traffic and can be used to evaluate lumpy reclaim. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Larry Woodman <lwoodman@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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33906bc5 |
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09-Aug-2010 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: tracing: add trace events for kswapd wakeup, sleeping and direct reclaim Add two trace events for kswapd waking up and going asleep for the purposes of tracking kswapd activity and two trace events for direct reclaim beginning and ending. The information can be used to work out how much time a process or the system is spending on the reclamation of pages and in the case of direct reclaim, how many pages were reclaimed for that process. High frequency triggering of these events could point to memory pressure problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Larry Woodman <lwoodman@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c6a8a8c5 |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: recalculate lru_pages on each priority shrink_zones() need relatively long time and lru_pages can change dramatically during shrink_zones(). So lru_pages should be recalculated for each priority. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b00d3ea7 |
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09-Aug-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: zone_reclaim don't call disable_swap_token() Swap token don't works when zone reclaim is enabled since it was born. Because __zone_reclaim() always call disable_swap_token() unconditionally. This kill swap token feature completely. As far as I know, nobody want to that. Remove it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a6aa62a0 |
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20-Jul-2010 |
Nick Piggin <npiggin@suse.de> |
mm/vmscan.c: fix mapping use after free We need lock_page_nosync() here because we have no reference to the mapping when taking the page lock. Signed-off-by: Nick Piggin <npiggin@suse.de> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7f8275d0 |
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18-Jul-2010 |
Dave Chinner <dchinner@redhat.com> |
mm: add context argument to shrinker callback The current shrinker implementation requires the registered callback to have global state to work from. This makes it difficult to shrink caches that are not global (e.g. per-filesystem caches). Pass the shrinker structure to the callback so that users can embed the shrinker structure in the context the shrinker needs to operate on and get back to it in the callback via container_of(). Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
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bb21c7ce |
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04-Jun-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure Greg Thelen reported recent Johannes's stack diet patch makes kernel hang. His test is following. mount -t cgroup none /cgroups -o memory mkdir /cgroups/cg1 echo $$ > /cgroups/cg1/tasks dd bs=1024 count=1024 if=/dev/null of=/data/foo echo $$ > /cgroups/tasks echo 1 > /cgroups/cg1/memory.force_empty Actually, This OOM hard to try logic have been corrupted since following two years old patch. commit a41f24ea9fd6169b147c53c2392e2887cc1d9247 Author: Nishanth Aravamudan <nacc@us.ibm.com> Date: Tue Apr 29 00:58:25 2008 -0700 page allocator: smarter retry of costly-order allocations Original intention was "return success if the system have shrinkable zones though priority==0 reclaim was failure". But the above patch changed to "return nr_reclaimed if .....". Oh, That forgot nr_reclaimed may be 0 if priority==0 reclaim failure. And Johannes's patch 0aeb2339e54e ("vmscan: remove all_unreclaimable scan control") made it more corrupt. Originally, priority==0 reclaim failure on memcg return 0, but this patch changed to return 1. It totally confused memcg. This patch fixes it completely. Reported-by: Greg Thelen <gthelen@google.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Greg Thelen <gthelen@google.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8b25c6d2 |
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24-May-2010 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: remove isolate_pages callback scan control For now, we have global isolation vs. memory control group isolation, do not allow the reclaim entry function to set an arbitrary page isolation callback, we do not need that flexibility. And since we already pass around the group descriptor for the memory control group isolation case, just use it to decide which one of the two isolator functions to use. The decisions can be merged into nearby branches, so no extra cost there. In fact, we save the indirect calls. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0aeb2339 |
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24-May-2010 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: remove all_unreclaimable scan control This scan control is abused to communicate a return value from shrink_zones(). Write this idiomatically and remove the knob. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5f53e762 |
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24-May-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: page_check_references(): check low order lumpy reclaim properly If vmscan is under lumpy reclaim mode, it have to ignore referenced bit for making contenious free pages. but current page_check_references() doesn't. Fix it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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76a33fc3 |
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24-May-2010 |
Shaohua Li <shaohua.li@intel.com> |
vmscan: prevent get_scan_ratio() rounding errors get_scan_ratio() calculates percentage and if the percentage is < 1%, it will round percentage down to 0% and cause we completely ignore scanning anon/file pages to reclaim memory even the total anon/file pages are very big. To avoid underflow, we don't use percentage, instead we directly calculate how many pages should be scaned. In this way, we should get several scanned pages for < 1% percent. This has some benefits: 1. increase our calculation precision 2. making our scan more smoothly. Without this, if percent[x] is underflow, shrink_zone() doesn't scan any pages and suddenly it scans all pages when priority is zero. With this, even priority isn't zero, shrink_zone() gets chance to scan some pages. Note, this patch doesn't really change logics, but just increase precision. For system with a lot of memory, this might slightly changes behavior. For example, in a sequential file read workload, without the patch, we don't swap any anon pages. With it, if anon memory size is bigger than 16G, we will see one anon page swapped. The 16G is calculated as PAGE_SIZE * priority(4096) * (fp/ap). fp/ap is assumed to be 1024 which is common in this workload. So the impact sounds not a big deal. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c175a0ce |
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24-May-2010 |
Mel Gorman <mel@csn.ul.ie> |
mm: move definition for LRU isolation modes to a header Currently, vmscan.c defines the isolation modes for __isolate_lru_page(). Memory compaction needs access to these modes for isolating pages for migration. This patch exports them. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <cl@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c0ff7453 |
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24-May-2010 |
Miao Xie <miaox@cn.fujitsu.com> |
cpuset,mm: fix no node to alloc memory when changing cpuset's mems Before applying this patch, cpuset updates task->mems_allowed and mempolicy by setting all new bits in the nodemask first, and clearing all old unallowed bits later. But in the way, the allocator may find that there is no node to alloc memory. The reason is that cpuset rebinds the task's mempolicy, it cleans the nodes which the allocater can alloc pages on, for example: (mpol: mempolicy) task1 task1's mpol task2 alloc page 1 alloc on node0? NO 1 1 change mems from 1 to 0 1 rebind task1's mpol 0-1 set new bits 0 clear disallowed bits alloc on node1? NO 0 ... can't alloc page goto oom This patch fixes this problem by expanding the nodes range first(set newly allowed bits) and shrink it lazily(clear newly disallowed bits). So we use a variable to tell the write-side task that read-side task is reading nodemask, and the write-side task clears newly disallowed nodes after read-side task ends the current memory allocation. [akpm@linux-foundation.org: fix spello] Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Paul Menage <menage@google.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d6da1a5a |
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06-Apr-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: revert "vmscan: get_scan_ratio() cleanup" Shaohua Li reported his tmpfs streaming I/O test can lead to make oom. The test uses a 6G tmpfs in a system with 3G memory. In the tmpfs, there are 6 copies of kernel source and the test does kbuild for each copy. His investigation shows the test has a lot of rotated anon pages and quite few file pages, so get_scan_ratio calculates percent[0] (i.e. scanning percent for anon) to be zero. Actually the percent[0] shoule be a big value, but our calculation round it to zero. Although before commit 84b18490 ("vmscan: get_scan_ratio() cleanup") , we have the same problem too. But the old logic can rescue percent[0]==0 case only when priority==0. It had hided the real issue. I didn't think merely streaming io can makes percent[0]==0 && priority==0 situation. but I was wrong. So, definitely we have to fix such tmpfs streaming io issue. but anyway I revert the regression commit at first. This reverts commit 84b18490d1f1bc7ed5095c929f78bc002eb70f26. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reported-by: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5a0e3ad6 |
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24-Mar-2010 |
Tejun Heo <tj@kernel.org> |
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
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64574746 |
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05-Mar-2010 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: detect mapped file pages used only once The VM currently assumes that an inactive, mapped and referenced file page is in use and promotes it to the active list. However, every mapped file page starts out like this and thus a problem arises when workloads create a stream of such pages that are used only for a short time. By flooding the active list with those pages, the VM quickly gets into trouble finding eligible reclaim canditates. The result is long allocation latencies and eviction of the wrong pages. This patch reuses the PG_referenced page flag (used for unmapped file pages) to implement a usage detection that scales with the speed of LRU list cycling (i.e. memory pressure). If the scanner encounters those pages, the flag is set and the page cycled again on the inactive list. Only if it returns with another page table reference it is activated. Otherwise it is reclaimed as 'not recently used cache'. This effectively changes the minimum lifetime of a used-once mapped file page from a full memory cycle to an inactive list cycle, which allows it to occur in linear streams without affecting the stable working set of the system. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: OSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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31c0569c |
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05-Mar-2010 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: drop page_mapping_inuse() page_mapping_inuse() is a historic predicate function for pages that are about to be reclaimed or deactivated. According to it, a page is in use when it is mapped into page tables OR part of swap cache OR backing an mmapped file. This function is used in combination with page_referenced(), which checks for young bits in ptes and the page descriptor itself for the PG_referenced bit. Thus, checking for unmapped swap cache pages is meaningless as PG_referenced is not set for anonymous pages and unmapped pages do not have young ptes. The test makes no difference. Protecting file pages that are not by themselves mapped but are part of a mapped file is also a historic leftover for short-lived things like the exec() code in libc. However, the VM now does reference accounting and activation of pages at unmap time and thus the special treatment on reclaim is obsolete. This patch drops page_mapping_inuse() and switches the two callsites to use page_mapped() directly. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: OSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dfc8d636 |
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05-Mar-2010 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: factor out page reference checks The used-once mapped file page detection patchset. It is meant to help workloads with large amounts of shortly used file mappings, like rtorrent hashing a file or git when dealing with loose objects (git gc on a bigger site?). Right now, the VM activates referenced mapped file pages on first encounter on the inactive list and it takes a full memory cycle to reclaim them again. When those pages dominate memory, the system no longer has a meaningful notion of 'working set' and is required to give up the active list to make reclaim progress. Obviously, this results in rather bad scanning latencies and the wrong pages being reclaimed. This patch makes the VM be more careful about activating mapped file pages in the first place. The minimum granted lifetime without another memory access becomes an inactive list cycle instead of the full memory cycle, which is more natural given the mentioned loads. This test resembles a hashing rtorrent process. Sequentially, 32MB chunks of a file are mapped into memory, hashed (sha1) and unmapped again. While this happens, every 5 seconds a process is launched and its execution time taken: python2.4 -c 'import pydoc' old: max=2.31s mean=1.26s (0.34) new: max=1.25s mean=0.32s (0.32) find /etc -type f old: max=2.52s mean=1.44s (0.43) new: max=1.92s mean=0.12s (0.17) vim -c ':quit' old: max=6.14s mean=4.03s (0.49) new: max=3.48s mean=2.41s (0.25) mplayer --help old: max=8.08s mean=5.74s (1.02) new: max=3.79s mean=1.32s (0.81) overall hash time (stdev): old: time=1192.30 (12.85) thruput=25.78mb/s (0.27) new: time=1060.27 (32.58) thruput=29.02mb/s (0.88) (-11%) I also tested kernbench with regular IO streaming in the background to see whether the delayed activation of frequently used mapped file pages had a negative impact on performance in the presence of pressure on the inactive list. The patch made no significant difference in timing, neither for kernbench nor for the streaming IO throughput. The first patch submission raised concerns about the cost of the extra faults for actually activated pages on machines that have no hardware support for young page table entries. I created an artificial worst case scenario on an ARM machine with around 300MHz and 64MB of memory to figure out the dimensions involved. The test would mmap a file of 20MB, then 1. touch all its pages to fault them in 2. force one full scan cycle on the inactive file LRU -- old: mapping pages activated -- new: mapping pages inactive 3. touch the mapping pages again -- old and new: fault exceptions to set the young bits 4. force another full scan cycle on the inactive file LRU 5. touch the mapping pages one last time -- new: fault exceptions to set the young bits The test showed an overall increase of 6% in time over 100 iterations of the above (old: ~212sec, new: ~225sec). 13 secs total overhead / (100 * 5k pages), ignoring the execution time of the test itself, makes for about 25us overhead for every page that gets actually activated. Note: 1. File mapping the size of one third of main memory, _completely_ in active use across memory pressure - i.e., most pages referenced within one LRU cycle. This should be rare to non-existant, especially on such embedded setups. 2. Many huge activation batches. Those batches only occur when the working set fluctuates. If it changes completely between every full LRU cycle, you have problematic reclaim overhead anyway. 3. Access of activated pages at maximum speed: sequential loads from every single page without doing anything in between. In reality, the extra faults will get distributed between actual operations on the data. So even if a workload manages to get the VM into the situation of activating a third of memory in one go on such a setup, it will take 2.2 seconds instead 2.1 without the patch. Comparing the numbers (and my user-experience over several months), I think this change is an overall improvement to the VM. Patch 1 is only refactoring to break up that ugly compound conditional in shrink_page_list() and make it easy to document and add new checks in a readable fashion. Patch 2 gets rid of the obsolete page_mapping_inuse(). It's not strictly related to #3, but it was in the original submission and is a net simplification, so I kept it. Patch 3 implements used-once detection of mapped file pages. This patch: Moving the big conditional into its own predicate function makes the code a bit easier to read and allows for better commenting on the checks one-by-one. This is just cleaning up, no semantics should have been changed. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: OSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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93e4a89a |
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05-Mar-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: restore zone->all_unreclaimable to independence word commit e815af95 ("change all_unreclaimable zone member to flags") changed all_unreclaimable member to bit flag. But it had an undesireble side effect. free_one_page() is one of most hot path in linux kernel and increasing atomic ops in it can reduce kernel performance a bit. Thus, this patch revert such commit partially. at least all_unreclaimable shouldn't share memory word with other zone flags. [akpm@linux-foundation.org: fix patch interaction] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Huang Shijie <shijie8@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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76ca542d |
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05-Mar-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm, lockdep: annotate reclaim context to zone reclaim too Commit cf40bd16fd ("lockdep: annotate reclaim context") introduced reclaim context annotation. But it didn't annotate zone reclaim. This patch do it. The point is, commit cf40bd16fd annotate __alloc_pages_direct_reclaim but zone-reclaim doesn't use __alloc_pages_direct_reclaim. current call graph is __alloc_pages_nodemask get_page_from_freelist zone_reclaim() __alloc_pages_slowpath __alloc_pages_direct_reclaim try_to_free_pages Actually, if zone_reclaim_mode=1, VM never call __alloc_pages_direct_reclaim in usual VM pressure. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Nick Piggin <npiggin@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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84b18490 |
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05-Mar-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: get_scan_ratio() cleanup The get_scan_ratio() should have all scan-ratio related calculations. Thus, this patch move some calculation into get_scan_ratio. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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45973d74 |
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05-Mar-2010 |
Minchan Kim <minchan.kim@gmail.com> |
vmscan: check high watermark after shrink zone Kswapd checks that zone has sufficient pages free via zone_watermark_ok(). If any zone doesn't have enough pages, we set all_zones_ok to zero. !all_zone_ok makes kswapd retry rather than sleeping. I think the watermark check before shrink_zone() is pointless. Only after kswapd has tried to shrink the zone is the check meaningful. Move the check to after the call to shrink_zone(). [akpm@linux-foundation.org: fix comment, layout] Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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de3fab39 |
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15-Jan-2010 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: kswapd: don't retry balance_pgdat() if all zones are unreclaimable Commit f50de2d3 (vmscan: have kswapd sleep for a short interval and double check it should be asleep) can cause kswapd to enter an infinite loop if running on a single-CPU system. If all zones are unreclaimble, sleeping_prematurely return 1 and kswapd will call balance_pgdat() again. but it's totally meaningless, balance_pgdat() doesn't anything against unreclaimable zone! Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Reported-by: Will Newton <will.newton@gmail.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Tested-by: Will Newton <will.newton@gmail.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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62c0c2f1 |
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14-Dec-2009 |
Huang Shijie <shijie8@gmail.com> |
vmscan: simplify code Simplify the code for shrink_inactive_list(). Signed-off-by: Huang Shijie <shijie8@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b39415b2 |
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14-Dec-2009 |
Rik van Riel <riel@redhat.com> |
vmscan: do not evict inactive pages when skipping an active list scan In AIM7 runs, recent kernels start swapping out anonymous pages well before they should. This is due to shrink_list falling through to shrink_inactive_list if !inactive_anon_is_low(zone, sc), when all we really wanted to do is pre-age some anonymous pages to give them extra time to be referenced while on the inactive list. The obvious fix is to make sure that shrink_list does not fall through to scanning/reclaiming inactive pages when we called it to scan one of the active lists. This change should be safe because the loop in shrink_zone ensures that we will still shrink the anon and file inactive lists whenever we should. [kosaki.motohiro@jp.fujitsu.com: inactive_file_is_low() should be inactive_anon_is_low()] Reported-by: Larry Woodman <lwoodman@redhat.com> Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tomasz Chmielewski <mangoo@wpkg.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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338fde90 |
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14-Dec-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: make consistent of reclaim bale out between do_try_to_free_page and shrink_zone Fix small inconsistent of ">" and ">=". Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ece74b2e |
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14-Dec-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: kill sc.swap_cluster_max Now, All caller of reclaim use swap_cluster_max as SWAP_CLUSTER_MAX. Then, we can remove it perfectly. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4f0ddfdf |
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14-Dec-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: zone_reclaim() don't use insane swap_cluster_max In old days, we didn't have sc.nr_to_reclaim and it brought sc.swap_cluster_max misuse. huge sc.swap_cluster_max might makes unnecessary OOM risk and no performance benefit. Now, we can stop its insane thing. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7b51755c |
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14-Dec-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: kill hibernation specific reclaim logic and unify it shrink_all_zone() was introduced by commit d6277db4ab (swsusp: rework memory shrinker) for hibernate performance improvement. and sc.swap_cluster_max was introduced by commit a06fe4d307 (Speed freeing memory for suspend). commit a06fe4d307 said Without the patch: Freed 14600 pages in 1749 jiffies = 32.61 MB/s (Anomolous!) Freed 88563 pages in 14719 jiffies = 23.50 MB/s Freed 205734 pages in 32389 jiffies = 24.81 MB/s With the patch: Freed 68252 pages in 496 jiffies = 537.52 MB/s Freed 116464 pages in 569 jiffies = 798.54 MB/s Freed 209699 pages in 705 jiffies = 1161.89 MB/s At that time, their patch was pretty worth. However, Modern Hardware trend and recent VM improvement broke its worth. From several reason, I think we should remove shrink_all_zones() at all. detail: 1) Old days, shrink_zone()'s slowness was mainly caused by stupid io-throttle at no i/o congestion. but current shrink_zone() is sane, not slow. 2) shrink_all_zone() try to shrink all pages at a time. but it doesn't works fine on numa system. example) System has 4GB memory and each node have 2GB. and hibernate need 1GB. optimal) steal 500MB from each node. shrink_all_zones) steal 1GB from node-0. Oh, Cache balancing logic was broken. ;) Unfortunately, Desktop system moved ahead NUMA at nowadays. (Side note, if hibernate require 2GB, shrink_all_zones() never success on above machine) 3) if the node has several I/O flighting pages, shrink_all_zones() makes pretty bad result. schenario) hibernate need 1GB 1) shrink_all_zones() try to reclaim 1GB from Node-0 2) but it only reclaimed 990MB 3) stupidly, shrink_all_zones() try to reclaim 1GB from Node-1 4) it reclaimed 990MB Oh, well. it reclaimed twice much than required. In the other hand, current shrink_zone() has sane baling out logic. then, it doesn't make overkill reclaim. then, we lost shrink_zones()'s risk. 4) SplitLRU VM always keep active/inactive ratio very carefully. inactive list only shrinking break its assumption. it makes unnecessary OOM risk. it obviously suboptimal. Now, shrink_all_memory() is only the wrapper function of do_try_to_free_pages(). it bring good reviewability and debuggability, and solve above problems. side note: Reclaim logic unificication makes two good side effect. - Fix recursive reclaim bug on shrink_all_memory(). it did forgot to use PF_MEMALLOC. it mean the system be able to stuck into deadlock. - Now, shrink_all_memory() got lockdep awareness. it bring good debuggability. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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22fba335 |
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14-Dec-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: separate sc.swap_cluster_max and sc.nr_max_reclaim Currently, sc.scap_cluster_max has double meanings. 1) reclaim batch size as isolate_lru_pages()'s argument 2) reclaim baling out thresolds The two meanings pretty unrelated. Thus, Let's separate it. this patch doesn't change any behavior. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bb3ab596 |
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14-Dec-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: stop kswapd waiting on congestion when the min watermark is not being met If reclaim fails to make sufficient progress, the priority is raised. Once the priority is higher, kswapd starts waiting on congestion. However, if the zone is below the min watermark then kswapd needs to continue working without delay as there is a danger of an increased rate of GFP_ATOMIC allocation failure. This patch changes the conditions under which kswapd waits on congestion by only going to sleep if the min watermarks are being met. [mel@csn.ul.ie: add stats to track how relevant the logic is] [mel@csn.ul.ie: make kswapd only check its own zones and rename the relevant counters] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f50de2d3 |
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14-Dec-2009 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: have kswapd sleep for a short interval and double check it should be asleep After kswapd balances all zones in a pgdat, it goes to sleep. In the event of no IO congestion, kswapd can go to sleep very shortly after the high watermark was reached. If there are a constant stream of allocations from parallel processes, it can mean that kswapd went to sleep too quickly and the high watermark is not being maintained for sufficient length time. This patch makes kswapd go to sleep as a two-stage process. It first tries to sleep for HZ/10. If it is woken up by another process or the high watermark is no longer met, it's considered a premature sleep and kswapd continues work. Otherwise it goes fully to sleep. This adds more counters to distinguish between fast and slow breaches of watermarks. A "fast" premature sleep is one where the low watermark was hit in a very short time after kswapd going to sleep. A "slow" premature sleep indicates that the high watermark was breached after a very short interval. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Frans Pop <elendil@planet.nl> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6aceb53b |
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14-Dec-2009 |
Vincent Li <macli@brc.ubc.ca> |
mm/vmscan: change comment generic_file_write to __generic_file_aio_write Commit 543ade1fc9 ("Streamline generic_file_* interfaces and filemap cleanups") removed generic_file_write() in filemap. Change the comment in vmscan pageout() to __generic_file_aio_write(). Signed-off-by: Vincent Li <macli@brc.ubc.ca> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8fe23e05 |
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14-Dec-2009 |
David Rientjes <rientjes@google.com> |
mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is offlined When memory is hot-removed, its node must be cleared in N_HIGH_MEMORY if there are no present pages left. In such a situation, kswapd must also be stopped since it has nothing left to do. Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Rientjes <rientjes@google.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6a7b9548 |
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26-Oct-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: order evictable rescue in LRU putback Isolators putting a page back to the LRU do not hold the page lock, and if the page is mlocked, another thread might munlock it concurrently. Expecting this, the putback code re-checks the evictability of a page when it just moved it to the unevictable list in order to correct its decision. The problem, however, is that ordering is not garuanteed between setting PG_lru when moving the page to the list and checking PG_mlocked afterwards: #0: #1 spin_lock() if (TestClearPageMlocked()) if (PageLRU()) move to evictable list SetPageLRU() spin_unlock() if (!PageMlocked()) move to evictable list The PageMlocked() check may get reordered before SetPageLRU() in #0, resulting in #0 not moving the still mlocked page, and in #1 failing to isolate and move the page as well. The page is now stranded on the unevictable list. The race condition is very unlikely. The consequence currently is one page falling off the reclaim grid and eventually getting freed with PG_unevictable set, which triggers a warning in the page allocator. TestClearPageMlocked() in #1 already provides full memory barrier semantics. This patch adds an explicit full barrier to force ordering between SetPageLRU() and PageMlocked() so that either one of the competitors rescues the page. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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41e20983 |
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26-Oct-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: limit VM_EXEC protection to file pages It is possible to have !Anon but SwapBacked pages, and some apps could create huge number of such pages with MAP_SHARED|MAP_ANONYMOUS. These pages go into the ANON lru list, and hence shall not be protected: we only care mapped executable files. Failing to do so may trigger OOM. Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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58355c78 |
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26-Oct-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
congestion_wait(): don't use WRITE commit 8aa7e847d (Fix congestion_wait() sync/async vs read/write confusion) replace WRITE with BLK_RW_ASYNC. Unfortunately, concurrent mm development made the unchanged place accidentally. This patch fixes it too. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5b0830cb |
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23-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: get rid to incorrect references to pdflush in comments Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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8d65af78 |
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23-Sep-2009 |
Alexey Dobriyan <adobriyan@gmail.com> |
sysctl: remove "struct file *" argument of ->proc_handler It's unused. It isn't needed -- read or write flag is already passed and sysctl shouldn't care about the rest. It _was_ used in two places at arch/frv for some reason. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4e416953 |
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23-Sep-2009 |
Balbir Singh <balbir@linux.vnet.ibm.com> |
memory controller: soft limit reclaim on contention Implement reclaim from groups over their soft limit Permit reclaim from memory cgroups on contention (via the direct reclaim path). memory cgroup soft limit reclaim finds the group that exceeds its soft limit by the largest number of pages and reclaims pages from it and then reinserts the cgroup into its correct place in the rbtree. Add additional checks to mem_cgroup_hierarchical_reclaim() to detect long loops in case all swap is turned off. The code has been refactored and the loop check (loop < 2) has been enhanced for soft limits. For soft limits, we try to do more targetted reclaim. Instead of bailing out after two loops, the routine now reclaims memory proportional to the size by which the soft limit is exceeded. The proportion has been empirically determined. [akpm@linux-foundation.org: build fix] [kamezawa.hiroyu@jp.fujitsu.com: fix softlimit css refcnt handling] [nishimura@mxp.nes.nec.co.jp: refcount of the "victim" should be decremented before exiting the loop] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f168e1b6 |
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21-Sep-2009 |
Vincent Li <macli@brc.ubc.ca> |
mm/vmscan: remove page_queue_congested() comment Commit 084f71ae5c(kill page_queue_congested()) removed page_queue_congested(). Remove the page_queue_congested() comment in vmscan pageout() too. Signed-off-by: Vincent Li <macli@brc.ubc.ca> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f8629631 |
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21-Sep-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
mm: do batched scans for mem_cgroup For mem_cgroup, shrink_zone() may call shrink_list() with nr_to_scan=1, in which case shrink_list() _still_ calls isolate_pages() with the much larger SWAP_CLUSTER_MAX. It effectively scales up the inactive list scan rate by up to 32 times. For example, with 16k inactive pages and DEF_PRIORITY=12, (16k >> 12)=4. So when shrink_zone() expects to scan 4 pages in the active/inactive list, the active list will be scanned 4 pages, while the inactive list will be (over) scanned SWAP_CLUSTER_MAX=32 pages in effect. And that could break the balance between the two lists. It can further impact the scan of anon active list, due to the anon active/inactive ratio rebalance logic in balance_pgdat()/shrink_zone(): inactive anon list over scanned => inactive_anon_is_low() == TRUE => shrink_active_list() => active anon list over scanned So the end result may be - anon inactive => over scanned - anon active => over scanned (maybe not as much) - file inactive => over scanned - file active => under scanned (relatively) The accesses to nr_saved_scan are not lock protected and so not 100% accurate, however we can tolerate small errors and the resulted small imbalanced scan rates between zones. Cc: Rik van Riel <riel@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0b217676 |
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21-Sep-2009 |
Vincent Li <macli@brc.ubc.ca> |
mm/vmscan: rename zone_nr_pages() to zone_nr_lru_pages() The name `zone_nr_pages' can be mis-read as zone's (total) number pages, but it actually returns zone's LRU list number pages. Signed-off-by: Vincent Li <macli@brc.ubc.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ceddc3a5 |
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21-Sep-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: document is_page_cache_freeable() Enlighten the reader of this code about what reference count makes a page cache page freeable. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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edcf4748 |
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21-Sep-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: return boolean from page_has_private() Make page_has_private() return a true boolean value and remove the double negations from the two callsites using it for arithmetic. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6c0b1351 |
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21-Sep-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: return boolean from page_is_file_cache() page_is_file_cache() has been used for both boolean checks and LRU arithmetic, which was always a bit weird. Now that page_lru_base_type() exists for LRU arithmetic, make page_is_file_cache() a real predicate function and adjust the boolean-using callsites to drop those pesky double negations. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
401a8e1c |
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21-Sep-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: introduce page_lru_base_type() Instead of abusing page_is_file_cache() for LRU list index arithmetic, add another helper with a more appropriate name and convert the non-boolean users of page_is_file_cache() accordingly. This new helper gives the LRU base type a page is supposed to live on, inactive anon or inactive file. [hugh.dickins@tiscali.co.uk: convert del_page_from_lru() also] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b7c46d15 |
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21-Sep-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: drop unneeded double negations Remove double negations where the operand is already boolean. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a26f5320 |
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21-Sep-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: kill unnecessary prefetch The pages in the list passed move_active_pages_to_lru() are already touched by shrink_active_list(). IOW the prefetch in move_active_pages_to_lru() don't populate any cache. it's pointless. This patch remove it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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74a1c48f |
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21-Sep-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: kill unnecessary page flag test The page_lru() already evaluate PageActive() and PageSwapBacked(). We don't need to re-evaluate it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5205e56e |
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21-Sep-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: move ClearPageActive from move_active_pages() to shrink_active_list() The move_active_pages_to_lru() function is called under irq disabled and ClearPageActive() doesn't need irq disabling. Then, this patch move it into shrink_active_list(). Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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de2e7567 |
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21-Sep-2009 |
Minchan Kim <minchan.kim@gmail.com> |
vmscan: don't attempt to reclaim anon page in lumpy reclaim when no swap space is available The VM already avoids attempting to reclaim anon pages in various places, But it doesn't avoid it for lumpy reclaim. It shuffles lru list unnecessary so that it is pointless. [akpm@linux-foundation.org: cleanup] Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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adea02a1 |
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21-Sep-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
mm: count only reclaimable lru pages global_lru_pages() / zone_lru_pages() can be used in two ways: - to estimate max reclaimable pages in determine_dirtyable_memory() - to calculate the slab scan ratio When swap is full or not present, the anon lru lists are not reclaimable and also won't be scanned. So the anon pages shall not be counted in both usage scenarios. Also rename to _reclaimable_pages: now they are counting the possibly reclaimable lru pages. It can greatly (and correctly) increase the slab scan rate under high memory pressure (when most file pages have been reclaimed and swap is full/absent), thus reduce false OOM kills. Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Howells <dhowells@redhat.com> Cc: "Li, Ming Chun" <macli@brc.ubc.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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35cd7815 |
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21-Sep-2009 |
Rik van Riel <riel@redhat.com> |
vmscan: throttle direct reclaim when too many pages are isolated already When way too many processes go into direct reclaim, it is possible for all of the pages to be taken off the LRU. One result of this is that the next process in the page reclaim code thinks there are no reclaimable pages left and triggers an out of memory kill. One solution to this problem is to never let so many processes into the page reclaim path that the entire LRU is emptied. Limiting the system to only having half of each inactive list isolated for reclaim should be safe. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a731286d |
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21-Sep-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: vmstat: add isolate pages If the system is running a heavy load of processes then concurrent reclaim can isolate a large number of pages from the LRU. /proc/vmstat and the output generated for an OOM do not show how many pages were isolated. This has been observed during process fork bomb testing (mstctl11 in LTP). This patch shows the information about isolated pages. Reproduced via: ----------------------- % ./hackbench 140 process 1000 => OOM occur active_anon:146 inactive_anon:0 isolated_anon:49245 active_file:79 inactive_file:18 isolated_file:113 unevictable:0 dirty:0 writeback:0 unstable:0 buffer:39 free:370 slab_reclaimable:309 slab_unreclaimable:5492 mapped:53 shmem:15 pagetables:28140 bounce:0 Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b35ea17b |
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21-Sep-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: shrink_inactive_list() nr_scan accounting fix fix If sc->isolate_pages() return 0, we don't need to call shrink_page_list(). In past days, shrink_inactive_list() handled it properly. But commit fb8d14e1 (three years ago commit!) breaked it. current shrink_inactive_list() always call shrink_page_list() although isolate_pages() return 0. This patch restore proper return value check. Requirements: o "nr_taken == 0" condition should stay before calling shrink_page_list(). o "nr_taken == 0" condition should stay after nr_scan related statistics modification. Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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44c241f1 |
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21-Sep-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: rename pgmoved variable in shrink_active_list() Currently the pgmoved variable has two meanings. It causes harder reviewing. This patch separates it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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14fa31b8 |
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16-Sep-2009 |
Andi Kleen <andi@firstfloor.org> |
HWPOISON: Use bitmask/action code for try_to_unmap behaviour try_to_unmap currently has multiple modi (migration, munlock, normal unmap) which are selected by magic flag variables. The logic is not very straight forward, because each of these flag change multiple behaviours (e.g. migration turns off aging, not only sets up migration ptes etc.) Also the different flags interact in magic ways. A later patch in this series adds another mode to try_to_unmap, so this becomes quickly unmanageable. Replace the different flags with a action code (migration, munlock, munmap) and some additional flags as modifiers (ignore mlock, ignore aging). This makes the logic more straight forward and allows easier extension to new behaviours. Change all the caller to declare what they want to do. This patch is supposed to be a nop in behaviour. If anyone can prove it is not that would be a bug. Cc: Lee.Schermerhorn@hp.com Cc: npiggin@suse.de Signed-off-by: Andi Kleen <ak@linux.intel.com>
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03ba3782 |
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09-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: switch to per-bdi threads for flushing data This gets rid of pdflush for bdi writeout and kupdated style cleaning. pdflush writeout suffers from lack of locality and also requires more threads to handle the same workload, since it has to work in a non-blocking fashion against each queue. This also introduces lumpy behaviour and potential request starvation, since pdflush can be starved for queue access if others are accessing it. A sample ffsb workload that does random writes to files is about 8% faster here on a simple SATA drive during the benchmark phase. File layout also seems a LOT more smooth in vmstat: r b swpd free buff cache si so bi bo in cs us sy id wa 0 1 0 608848 2652 375372 0 0 0 71024 604 24 1 10 48 42 0 1 0 549644 2712 433736 0 0 0 60692 505 27 1 8 48 44 1 0 0 476928 2784 505192 0 0 4 29540 553 24 0 9 53 37 0 1 0 457972 2808 524008 0 0 0 54876 331 16 0 4 38 58 0 1 0 366128 2928 614284 0 0 4 92168 710 58 0 13 53 34 0 1 0 295092 3000 684140 0 0 0 62924 572 23 0 9 53 37 0 1 0 236592 3064 741704 0 0 4 58256 523 17 0 8 48 44 0 1 0 165608 3132 811464 0 0 0 57460 560 21 0 8 54 38 0 1 0 102952 3200 873164 0 0 4 74748 540 29 1 10 48 41 0 1 0 48604 3252 926472 0 0 0 53248 469 29 0 7 47 45 where vanilla tends to fluctuate a lot in the creation phase: r b swpd free buff cache si so bi bo in cs us sy id wa 1 1 0 678716 5792 303380 0 0 0 74064 565 50 1 11 52 36 1 0 0 662488 5864 319396 0 0 4 352 302 329 0 2 47 51 0 1 0 599312 5924 381468 0 0 0 78164 516 55 0 9 51 40 0 1 0 519952 6008 459516 0 0 4 78156 622 56 1 11 52 37 1 1 0 436640 6092 541632 0 0 0 82244 622 54 0 11 48 41 0 1 0 436640 6092 541660 0 0 0 8 152 39 0 0 51 49 0 1 0 332224 6200 644252 0 0 4 102800 728 46 1 13 49 36 1 0 0 274492 6260 701056 0 0 4 12328 459 49 0 7 50 43 0 1 0 211220 6324 763356 0 0 0 106940 515 37 1 10 51 39 1 0 0 160412 6376 813468 0 0 0 8224 415 43 0 6 49 45 1 1 0 85980 6452 886556 0 0 4 113516 575 39 1 11 54 34 0 2 0 85968 6452 886620 0 0 0 1640 158 211 0 0 46 54 A 10 disk test with btrfs performs 26% faster with per-bdi flushing. A SSD based writeback test on XFS performs over 20% better as well, with the throughput being very stable around 1GB/sec, where pdflush only manages 750MB/sec and fluctuates wildly while doing so. Random buffered writes to many files behave a lot better as well, as does random mmap'ed writes. A separate thread is added to sync the super blocks. In the long term, adding sync_supers_bdi() functionality could get rid of this thread again. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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03ef83af |
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26-Aug-2009 |
Minchan Kim <minchan.kim@gmail.com> |
mm: fix for infinite churning of mlocked pages An mlocked page might lose the isolatation race. This causes the page to clear PG_mlocked while it remains in a VM_LOCKED vma. This means it can be put onto the [in]active list. We can rescue it by using try_to_unmap() in shrink_page_list(). But now, As Wu Fengguang pointed out, vmscan has a bug. If the page has PG_referenced, it can't reach try_to_unmap() in shrink_page_list() but is put into the active list. If the page is referenced repeatedly, it can remain on the [in]active list without being moving to the unevictable list. This patch fixes it. Reported-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <<kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8aa7e847 |
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09-Jul-2009 |
Jens Axboe <jens.axboe@oracle.com> |
Fix congestion_wait() sync/async vs read/write confusion Commit 1faa16d22877f4839bd433547d770c676d1d964c accidentally broke the bdi congestion wait queue logic, causing us to wait on congestion for WRITE (== 1) when we really wanted BLK_RW_ASYNC (== 0) instead. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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cb4cbcf6 |
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22-Jun-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
mm: fix incorrect page removal from LRU The isolated page is "cursor_page" not "page". This could cause LRU list corruption under memory pressure, caught by CONFIG_DEBUG_LIST. Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Balbir Singh <balbir@linux.vnet.ibm.com> Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2ffebca6 |
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17-Jun-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: fix lru rotation in isolate_pages Try to fix memcg's lru rotation sanity: make memcg use the same logic as the global LRU does. Now, at __isolate_lru_page() retruns -EBUSY, the page is rotated to the tail of LRU in global LRU's isolate LRU pages. But in memcg, it's not handled. This makes memcg do the same behavior as global LRU and rotate LRU in the page is busy. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ee993b13 |
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16-Jun-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
mm: fix lumpy reclaim lru handling at isolate_lru_pages At lumpy reclaim, a page failed to be taken by __isolate_lru_page() can be pushed back to "src" list by list_move(). But the page may not be from "src" list. This pushes the page back to wrong LRU. And list_move() itself is unnecessary because the page is not on top of LRU. Then, leave it as it is if __isolate_lru_page() fails. Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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24cf72518 |
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16-Jun-2009 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: count the number of times zone_reclaim() scans and fails On NUMA machines, the administrator can configure zone_reclaim_mode that is a more targetted form of direct reclaim. On machines with large NUMA distances for example, a zone_reclaim_mode defaults to 1 meaning that clean unmapped pages will be reclaimed if the zone watermarks are not being met. There is a heuristic that determines if the scan is worthwhile but it is possible that the heuristic will fail and the CPU gets tied up scanning uselessly. Detecting the situation requires some guesswork and experimentation so this patch adds a counter "zreclaim_failed" to /proc/vmstat. If during high CPU utilisation this counter is increasing rapidly, then the resolution to the problem may be to set /proc/sys/vm/zone_reclaim_mode to 0. [akpm@linux-foundation.org: name things consistently] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fa5e084e |
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16-Jun-2009 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: do not unconditionally treat zones that fail zone_reclaim() as full On NUMA machines, the administrator can configure zone_reclaim_mode that is a more targetted form of direct reclaim. On machines with large NUMA distances for example, a zone_reclaim_mode defaults to 1 meaning that clean unmapped pages will be reclaimed if the zone watermarks are not being met. The problem is that zone_reclaim() failing at all means the zone gets marked full. This can cause situations where a zone is usable, but is being skipped because it has been considered full. Take a situation where a large tmpfs mount is occuping a large percentage of memory overall. The pages do not get cleaned or reclaimed by zone_reclaim(), but the zone gets marked full and the zonelist cache considers them not worth trying in the future. This patch makes zone_reclaim() return more fine-grained information about what occured when zone_reclaim() failued. The zone only gets marked full if it really is unreclaimable. If it's a case that the scan did not occur or if enough pages were not reclaimed with the limited reclaim_mode, then the zone is simply skipped. There is a side-effect to this patch. Currently, if zone_reclaim() successfully reclaimed SWAP_CLUSTER_MAX, an allocation attempt would go ahead. With this patch applied, zone watermarks are rechecked after zone_reclaim() does some work. This bug was introduced by commit 9276b1bc96a132f4068fdee00983c532f43d3a26 ("memory page_alloc zonelist caching speedup") way back in 2.6.19 when the zonelist_cache was introduced. It was not intended that zone_reclaim() aggressively consider the zone to be full when it failed as full direct reclaim can still be an option. Due to the age of the bug, it should be considered a -stable candidate. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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90afa5de |
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16-Jun-2009 |
Mel Gorman <mel@csn.ul.ie> |
vmscan: properly account for the number of page cache pages zone_reclaim() can reclaim A bug was brought to my attention against a distro kernel but it affects mainline and I believe problems like this have been reported in various guises on the mailing lists although I don't have specific examples at the moment. The reported problem was that malloc() stalled for a long time (minutes in some cases) if a large tmpfs mount was occupying a large percentage of memory overall. The pages did not get cleaned or reclaimed by zone_reclaim() because the zone_reclaim_mode was unsuitable, but the lists are uselessly scanned frequencly making the CPU spin at near 100%. This patchset intends to address that bug and bring the behaviour of zone_reclaim() more in line with expectations which were noticed during investigation. It is based on top of mmotm and takes advantage of Kosaki's work with respect to zone_reclaim(). Patch 1 fixes the heuristics that zone_reclaim() uses to determine if the scan should go ahead. The broken heuristic is what was causing the malloc() stall as it uselessly scanned the LRU constantly. Currently, zone_reclaim is assuming zone_reclaim_mode is 1 and historically it could not deal with tmpfs pages at all. This fixes up the heuristic so that an unnecessary scan is more likely to be correctly avoided. Patch 2 notes that zone_reclaim() returning a failure automatically means the zone is marked full. This is not always true. It could have failed because the GFP mask or zone_reclaim_mode were unsuitable. Patch 3 introduces a counter zreclaim_failed that will increment each time the zone_reclaim scan-avoidance heuristics fail. If that counter is rapidly increasing, then zone_reclaim_mode should be set to 0 as a temporarily resolution and a bug reported because the scan-avoidance heuristic is still broken. This patch: On NUMA machines, the administrator can configure zone_reclaim_mode that is a more targetted form of direct reclaim. On machines with large NUMA distances for example, a zone_reclaim_mode defaults to 1 meaning that clean unmapped pages will be reclaimed if the zone watermarks are not being met. There is a heuristic that determines if the scan is worthwhile but the problem is that the heuristic is not being properly applied and is basically assuming zone_reclaim_mode is 1 if it is enabled. The lack of proper detection can manfiest as high CPU usage as the LRU list is scanned uselessly. Historically, once enabled it was depending on NR_FILE_PAGES which may include swapcache pages that the reclaim_mode cannot deal with. Patch vmscan-change-the-number-of-the-unmapped-files-in-zone-reclaim.patch by Kosaki Motohiro noted that zone_page_state(zone, NR_FILE_PAGES) included pages that were not file-backed such as swapcache and made a calculation based on the inactive, active and mapped files. This is far superior when zone_reclaim==1 but if RECLAIM_SWAP is set, then NR_FILE_PAGES is a reasonable starting figure. This patch alters how zone_reclaim() works out how many pages it might be able to reclaim given the current reclaim_mode. If RECLAIM_SWAP is set in the reclaim_mode it will either consider NR_FILE_PAGES as potential candidates or else use NR_{IN}ACTIVE}_PAGES-NR_FILE_MAPPED to discount swapcache and other non-file-backed pages. If RECLAIM_WRITE is not set, then NR_FILE_DIRTY number of pages are not candidates. If RECLAIM_SWAP is not set, then NR_FILE_MAPPED are not. [kosaki.motohiro@jp.fujitsu.com: Estimate unmapped pages minus tmpfs pages] [fengguang.wu@intel.com: Fix underflow problem in Kosaki's estimate] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Christoph Lameter <cl@linux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9198e96c |
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16-Jun-2009 |
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> |
vmscan: handle may_swap more strictly Commit 2e2e425989080cc534fc0fca154cae515f971cf5 ("vmscan,memcg: reintroduce sc->may_swap) add may_swap flag and handle it at get_scan_ratio(). But the result of get_scan_ratio() is ignored when priority == 0, so anon lru is scanned even if may_swap == 0 or nr_swap_pages == 0. IMHO, this is not an expected behavior. As for memcg especially, because of this behavior many and many pages are swapped-out just in vain when oom is invoked by mem+swap limit. This patch is for handling may_swap flag more strictly. Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3eb4140f |
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16-Jun-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: merge duplicate code in shrink_active_list() The "move pages to active list" and "move pages to inactive list" code blocks are mostly identical and can be served by a function. Thanks to Andrew Morton for pointing this out. Note that buffer_heads_over_limit check will also be carried out for re-activated pages, which is slightly different from pre-2.6.28 kernels. Also, Rik's "vmscan: evict use-once pages first" patch could totally stop scans of active file list when memory pressure is low. So the net effect could be, the number of buffer heads is now more likely to grow large. However that's fine according to Johannes' comments: I don't think that this could be harmful. We just preserve the buffer mappings of what we consider the working set and with low memory pressure, as you say, this set is not big. As to stripping of reactivated pages: the only pages we re-activate for now are those VM_EXEC mapped ones. Since we don't expect IO from or to these pages, removing the buffer mappings in case they grow too large should be okay, I guess. Cc: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8cab4754 |
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16-Jun-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: make mapped executable pages the first class citizen Protect referenced PROT_EXEC mapped pages from being deactivated. PROT_EXEC(or its internal presentation VM_EXEC) pages normally belong to some currently running executables and their linked libraries, they shall really be cached aggressively to provide good user experiences. Thanks to Johannes Weiner for the advice to reuse the VMA walk in page_referenced() to get the PROT_EXEC bit. [more details] ( The consequences of this patch will have to be discussed together with Rik van Riel's recent patch "vmscan: evict use-once pages first". ) ( Some of the good points and insights are taken into this changelog. Thanks to all the involved people for the great LKML discussions. ) the problem =========== For a typical desktop, the most precious working set is composed of *actively accessed* (1) memory mapped executables (2) and their anonymous pages (3) and other files (4) and the dcache/icache/.. slabs while the least important data are (5) infrequently used or use-once files For a typical desktop, one major problem is busty and large amount of (5) use-once files flushing out the working set. Inside the working set, (4) dcache/icache have already been too sticky ;-) So we only have to care (2) anonymous and (1)(3) file pages. anonymous pages =============== Anonymous pages are effectively immune to the streaming IO attack, because we now have separate file/anon LRU lists. When the use-once files crowd into the file LRU, the list's "quality" is significantly lowered. Therefore the scan balance policy in get_scan_ratio() will choose to scan the (low quality) file LRU much more frequently than the anon LRU. file pages ========== Rik proposed to *not* scan the active file LRU when the inactive list grows larger than active list. This guarantees that when there are use-once streaming IO, and the working set is not too large(so that active_size < inactive_size), the active file LRU will *not* be scanned at all. So the not-too-large working set can be well protected. But there are also situations where the file working set is a bit large so that (active_size >= inactive_size), or the streaming IOs are not purely use-once. In these cases, the active list will be scanned slowly. Because the current shrink_active_list() policy is to deactivate active pages regardless of their referenced bits. The deactivated pages become susceptible to the streaming IO attack: the inactive list could be scanned fast (500MB / 50MBps = 10s) so that the deactivated pages don't have enough time to get re-referenced. Because a user tend to switch between windows in intervals from seconds to minutes. This patch holds mapped executable pages in the active list as long as they are referenced during each full scan of the active list. Because the active list is normally scanned much slower, they get longer grace time (eg. 100s) for further references, which better matches the pace of user operations. Therefore this patch greatly prolongs the in-cache time of executable code, when there are moderate memory pressures. before patch: guaranteed to be cached if reference intervals < I after patch: guaranteed to be cached if reference intervals < I+A (except when randomly reclaimed by the lumpy reclaim) where A = time to fully scan the active file LRU I = time to fully scan the inactive file LRU Note that normally A >> I. side effects ============ This patch is safe in general, it restores the pre-2.6.28 mmap() behavior but in a much smaller and well targeted scope. One may worry about some one to abuse the PROT_EXEC heuristic. But as Andrew Morton stated, there are other tricks to getting that sort of boost. Another concern is the PROT_EXEC mapped pages growing large in rare cases, and therefore hurting reclaim efficiency. But a sane application targeted for large audience will never use PROT_EXEC for data mappings. If some home made application tries to abuse that bit, it shall be aware of the consequences. If it is abused to scale of 2/3 total memory, it gains nothing but overheads. benchmarks ========== 1) memory tight desktop 1.1) brief summary - clock time and major faults are reduced by 50%; - pswpin numbers are reduced to ~1/3. That means X desktop responsiveness is doubled under high memory/swap pressure. 1.2) test scenario - nfsroot gnome desktop with 512M physical memory - run some programs, and switch between the existing windows after starting each new program. 1.3) progress timing (seconds) before after programs 0.02 0.02 N xeyes 0.75 0.76 N firefox 2.02 1.88 N nautilus 3.36 3.17 N nautilus --browser 5.26 4.89 N gthumb 7.12 6.47 N gedit 9.22 8.16 N xpdf /usr/share/doc/shared-mime-info/shared-mime-info-spec.pdf 13.58 12.55 N xterm 15.87 14.57 N mlterm 18.63 17.06 N gnome-terminal 21.16 18.90 N urxvt 26.24 23.48 N gnome-system-monitor 28.72 26.52 N gnome-help 32.15 29.65 N gnome-dictionary 39.66 36.12 N /usr/games/sol 43.16 39.27 N /usr/games/gnometris 48.65 42.56 N /usr/games/gnect 53.31 47.03 N /usr/games/gtali 58.60 52.05 N /usr/games/iagno 65.77 55.42 N /usr/games/gnotravex 70.76 61.47 N /usr/games/mahjongg 76.15 67.11 N /usr/games/gnome-sudoku 86.32 75.15 N /usr/games/glines 92.21 79.70 N /usr/games/glchess 103.79 88.48 N /usr/games/gnomine 113.84 96.51 N /usr/games/gnotski 124.40 102.19 N /usr/games/gnibbles 137.41 114.93 N /usr/games/gnobots2 155.53 125.02 N /usr/games/blackjack 179.85 135.11 N /usr/games/same-gnome 224.49 154.50 N /usr/bin/gnome-window-properties 248.44 162.09 N /usr/bin/gnome-default-applications-properties 282.62 173.29 N /usr/bin/gnome-at-properties 323.72 188.21 N /usr/bin/gnome-typing-monitor 363.99 199.93 N /usr/bin/gnome-at-visual 394.21 206.95 N /usr/bin/gnome-sound-properties 435.14 224.49 N /usr/bin/gnome-at-mobility 463.05 234.11 N /usr/bin/gnome-keybinding-properties 503.75 248.59 N /usr/bin/gnome-about-me 554.00 276.27 N /usr/bin/gnome-display-properties 615.48 304.39 N /usr/bin/gnome-network-preferences 693.03 342.01 N /usr/bin/gnome-mouse-properties 759.90 388.58 N /usr/bin/gnome-appearance-properties 937.90 508.47 N /usr/bin/gnome-control-center 1109.75 587.57 N /usr/bin/gnome-keyboard-properties 1399.05 758.16 N : oocalc 1524.64 830.03 N : oodraw 1684.31 900.03 N : ooimpress 1874.04 993.91 N : oomath 2115.12 1081.89 N : ooweb 2369.02 1161.99 N : oowriter Note that the last ": oo*" commands are actually commented out. 1.4) vmstat numbers (some relevant ones are marked with *) before after nr_free_pages 1293 3898 nr_inactive_anon 59956 53460 nr_active_anon 26815 30026 nr_inactive_file 2657 3218 nr_active_file 2019 2806 nr_unevictable 4 4 nr_mlock 4 4 nr_anon_pages 26706 27859 *nr_mapped 3542 4469 nr_file_pages 72232 67681 nr_dirty 1 0 nr_writeback 123 19 nr_slab_reclaimable 3375 3534 nr_slab_unreclaimable 11405 10665 nr_page_table_pages 8106 7864 nr_unstable 0 0 nr_bounce 0 0 *nr_vmscan_write 394776 230839 nr_writeback_temp 0 0 numa_hit 6843353 3318676 numa_miss 0 0 numa_foreign 0 0 numa_interleave 1719 1719 numa_local 6843353 3318676 numa_other 0 0 *pgpgin 5954683 2057175 *pgpgout 1578276 922744 *pswpin 1486615 512238 *pswpout 394568 230685 pgalloc_dma 277432 56602 pgalloc_dma32 6769477 3310348 pgalloc_normal 0 0 pgalloc_movable 0 0 pgfree 7048396 3371118 pgactivate 2036343 1471492 pgdeactivate 2189691 1612829 pgfault 3702176 3100702 *pgmajfault 452116 201343 pgrefill_dma 12185 7127 pgrefill_dma32 334384 653703 pgrefill_normal 0 0 pgrefill_movable 0 0 pgsteal_dma 74214 22179 pgsteal_dma32 3334164 1638029 pgsteal_normal 0 0 pgsteal_movable 0 0 pgscan_kswapd_dma 1081421 1216199 pgscan_kswapd_dma32 58979118 46002810 pgscan_kswapd_normal 0 0 pgscan_kswapd_movable 0 0 pgscan_direct_dma 2015438 1086109 pgscan_direct_dma32 55787823 36101597 pgscan_direct_normal 0 0 pgscan_direct_movable 0 0 pginodesteal 3461 7281 slabs_scanned 564864 527616 kswapd_steal 2889797 1448082 kswapd_inodesteal 14827 14835 pageoutrun 43459 21562 allocstall 9653 4032 pgrotated 384216 228631 1.5) free numbers at the end of the tests before patch: total used free shared buffers cached Mem: 474 467 7 0 0 236 -/+ buffers/cache: 230 243 Swap: 1023 418 605 after patch: total used free shared buffers cached Mem: 474 457 16 0 0 236 -/+ buffers/cache: 221 253 Swap: 1023 404 619 2) memory flushing in a file server 2.1) brief summary The number of major faults from 50 to 3 during 10% cache hot reads. That means this patch successfully stops major faults when the active file list is slowly scanned when there are partially cache hot streaming IO. 2.2) test scenario Do 100000 pread(size=110 pages, offset=(i*100) pages), where 10% of the pages will be activated: for i in `seq 0 100 10000000`; do echo $i 110; done > pattern-hot-10 iotrace.rb --load pattern-hot-10 --play /b/sparse vmmon nr_mapped nr_active_file nr_inactive_file pgmajfault pgdeactivate pgfree and monitor /proc/vmstat during the time. The test box has 2G memory. I carried out tests on fresh booted console as well as X desktop, and fetched the vmstat numbers on (1) begin: shortly after the big read IO starts; (2) end: just before the big read IO stops; (3) restore: the big read IO stops and the zsh working set restored (4) restore X: after IO, switch back and forth between the urxvt and firefox windows to restore their working set. 2.3) console mode results nr_mapped nr_active_file nr_inactive_file pgmajfault pgdeactivate pgfree 2.6.29 VM_EXEC protection ON: begin: 2481 2237 8694 630 0 574299 end: 275 231976 233914 633 776271 20933042 restore: 370 232154 234524 691 777183 20958453 2.6.29 VM_EXEC protection ON (second run): begin: 2434 2237 8493 629 0 574195 end: 284 231970 233536 632 771918 20896129 restore: 399 232218 234789 690 774526 20957909 2.6.30-rc4-mm VM_EXEC protection OFF: begin: 2479 2344 9659 210 0 579643 end: 284 232010 234142 260 772776 20917184 restore: 379 232159 234371 301 774888 20967849 The above console numbers show that - The startup pgmajfault of 2.6.30-rc4-mm is merely 1/3 that of 2.6.29. I'd attribute that improvement to the mmap readahead improvements :-) - The pgmajfault increment during the file copy is 633-630=3 vs 260-210=50. That's a huge improvement - which means with the VM_EXEC protection logic, active mmap pages is pretty safe even under partially cache hot streaming IO. - when active:inactive file lru size reaches 1:1, their scan rates is 1:20.8 under 10% cache hot IO. (computed with formula Dpgdeactivate:Dpgfree) That roughly means the active mmap pages get 20.8 more chances to get re-referenced to stay in memory. - The absolute nr_mapped drops considerably to 1/9 during the big IO, and the dropped pages are mostly inactive ones. The patch has almost no impact in this aspect, that means it won't unnecessarily increase memory pressure. (In contrast, your 20% mmap protection ratio will keep them all, and therefore eliminate the extra 41 major faults to restore working set of zsh etc.) The iotrace.rb read throughput is 151.194384MB/s 284.198252s 100001x 450560b --load pattern-hot-10 --play /b/sparse which means the inactive list is rotated at the speed of 250MB/s, so a full scan of which takes about 3.5 seconds, while a full scan of active file list takes about 77 seconds. 2.4) X mode results We can reach roughly the same conclusions for X desktop: nr_mapped nr_active_file nr_inactive_file pgmajfault pgdeactivate pgfree 2.6.30-rc4-mm VM_EXEC protection ON: begin: 9740 8920 64075 561 0 678360 end: 768 218254 220029 565 798953 21057006 restore: 857 218543 220987 606 799462 21075710 restore X: 2414 218560 225344 797 799462 21080795 2.6.30-rc4-mm VM_EXEC protection OFF: begin: 9368 5035 26389 554 0 633391 end: 770 218449 221230 661 646472 17832500 restore: 1113 218466 220978 710 649881 17905235 restore X: 2687 218650 225484 947 802700 21083584 - the absolute nr_mapped drops considerably (to 1/13 of the original size) during the streaming IO. - the delta of pgmajfault is 3 vs 107 during IO, or 236 vs 393 during the whole process. Cc: Elladan <elladan@eskimo.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: Christoph Lameter <cl@linux-foundation.org> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6fe6b7e3 |
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16-Jun-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: report vm_flags in page_referenced() Collect vma->vm_flags of the VMAs that actually referenced the page. This is preparing for more informed reclaim heuristics, eg. to protect executable file pages more aggressively. For now only the VM_EXEC bit will be used by the caller. Thanks to Johannes, Peter and Minchan for all the good tips. Acked-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cb4b86ba |
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16-Jun-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
mm: add swap cache interface for swap reference In a following patch, the usage of swap cache is recorded into swap_map. This patch is for necessary interface changes to do that. 2 interfaces: - swapcache_prepare() - swapcache_free() are added for allocating/freeing refcnt from swap-cache to existing swap entries. But implementation itself is not changed under this patch. At adding swapcache_free(), memcg's hook code is moved under swapcache_free(). This is better than using scattered hooks. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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68377659 |
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16-Jun-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: remove CONFIG_UNEVICTABLE_LRU config option Currently, nobody wants to turn UNEVICTABLE_LRU off. Thus this configurability is unnecessary. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andi Kleen <andi@firstfloor.org> Acked-by: Minchan Kim <minchan.kim@gmail.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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69c85481 |
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16-Jun-2009 |
MinChan Kim <minchan.kim@gmail.com> |
vmscan: prevent shrinking of active anon lru list in case of no swap space V3 shrink_zone() can deactivate active anon pages even if we don't have a swap device. Many embedded products don't have a swap device. So the deactivation of anon pages is unnecessary. This patch prevents unnecessary deactivation of anon lru pages. But, it don't prevent aging of anon pages to swap out. Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
af166777 |
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16-Jun-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: ZVC updates in shrink_active_list() can be done once This effectively lifts the unit of updates to nr_inactive_* and pgdeactivate from PAGEVEC_SIZE=14 to SWAP_CLUSTER_MAX=32, or MAX_ORDER_NR_PAGES=1024 for reclaim_zone(). Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
6e08a369 |
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16-Jun-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
vmscan: cleanup the scan batching code The vmscan batching logic is twisting. Move it into a standalone function nr_scan_try_batch() and document it. No behavior change. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux-foundation.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
56e49d21 |
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16-Jun-2009 |
Rik van Riel <riel@redhat.com> |
vmscan: evict use-once pages first When the file LRU lists are dominated by streaming IO pages, evict those pages first, before considering evicting other pages. This should be safe from deadlocks or performance problems because only three things can happen to an inactive file page: 1) referenced twice and promoted to the active list 2) evicted by the pageout code 3) under IO, after which it will get evicted or promoted The pages freed in this way can either be reused for streaming IO, or allocated for something else. If the pages are used for streaming IO, this pageout pattern continues. Otherwise, we will fall back to the normal pageout pattern. Signed-off-by: Rik van Riel <riel@redhat.com> Reported-by: Elladan <elladan@eskimo.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
41858966 |
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16-Jun-2009 |
Mel Gorman <mel@csn.ul.ie> |
page allocator: use allocation flags as an index to the zone watermark ALLOC_WMARK_MIN, ALLOC_WMARK_LOW and ALLOC_WMARK_HIGH determin whether pages_min, pages_low or pages_high is used as the zone watermark when allocating the pages. Two branches in the allocator hotpath determine which watermark to use. This patch uses the flags as an array index into a watermark array that is indexed with WMARK_* defines accessed via helpers. All call sites that use zone->pages_* are updated to use the helpers for accessing the values and the array offsets for setting. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
78dc583d |
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16-Jun-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: low order lumpy reclaim also should use PAGEOUT_IO_SYNC Commit 33c120ed2843090e2bd316de1588b8bf8b96cbde ("more aggressively use lumpy reclaim") increased how aggressive lumpy reclaim was by isolating both active and inactive pages for asynchronous lumpy reclaim on costly-high-order pages and for cheap-high-order when memory pressure is high. However, if the system is under heavy pressure and there are dirty pages, asynchronous IO may not be sufficient to reclaim a suitable page in time. This patch causes the caller to enter synchronous lumpy reclaim for costly-high-order pages and for cheap-high-order pages when under memory pressure. Minchan.kim@gmail.com said: Andy added synchronous lumpy reclaim with c661b078fd62abe06fd11fab4ac5e4eeafe26b6d. At that time, lumpy reclaim is not agressive. His intension is just for high-order users.(above PAGE_ALLOC_COSTLY_ORDER). After some time, Rik added aggressive lumpy reclaim with 33c120ed2843090e2bd316de1588b8bf8b96cbde. His intention was to do lumpy reclaim when high-order users and trouble getting a small set of contiguous pages. So we also have to add synchronous pageout for small set of contiguous pages. Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andy Whitcroft <apw@shadowen.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <Minchan.kim@gmail.com> Reviewed-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c6f37f12 |
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24-May-2009 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
PM/Suspend: Do not shrink memory before suspend Remove the shrinking of memory from the suspend-to-RAM code, where it is not really necessary. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Nigel Cunningham <nigel@tuxonice.net> Acked-by: Wu Fengguang <fengguang.wu@intel.com>
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#
e767e056 |
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28-May-2009 |
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> |
memcg: fix deadlock between lock_page_cgroup and mapping tree_lock mapping->tree_lock can be acquired from interrupt context. Then, following dead lock can occur. Assume "A" as a page. CPU0: lock_page_cgroup(A) interrupted -> take mapping->tree_lock. CPU1: take mapping->tree_lock -> lock_page_cgroup(A) This patch tries to fix above deadlock by moving memcg's hook to out of mapping->tree_lock. charge/uncharge of pagecache/swapcache is protected by page lock, not tree_lock. After this patch, lock_page_cgroup() is not called under mapping->tree_lock. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8713e012 |
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30-Apr-2009 |
Andrew Morton <akpm@linux-foundation.org> |
vmscan: avoid multiplication overflow in shrink_zone() Local variable `scan' can overflow on zones which are larger than (2G * 4k) / 100 = 80GB. Making it 64-bit on 64-bit will fix that up. Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2e2e4259 |
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21-Apr-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan,memcg: reintroduce sc->may_swap Commit a6dc60f8975ad96d162915e07703a4439c80dcf0 ("vmscan: rename sc.may_swap to may_unmap") removed the may_swap flag, but memcg had used it as a flag for "we need to use swap?", as the name indicate. And in the current implementation, memcg cannot reclaim mapped file caches when mem+swap hits the limit. re-introduce may_swap flag and handle it at get_scan_ratio(). This patch doesn't influence any scan_control users other than memcg. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a21e2553 |
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18-Apr-2009 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
PM/Hibernate: Fix memory shrinking Commit d979677c4c0 ("mm: shrink_all_memory(): use sc.nr_reclaimed") broke the memory shrinking used by hibernation, becuse it did not update shrink_all_zones() in accordance with the other changes it made. Fix this by making shrink_all_zones() update sc->nr_reclaimed instead of overwriting its value. This fixes http://bugzilla.kernel.org/show_bug.cgi?id=13058 Reported-and-tested-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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266cf658 |
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03-Apr-2009 |
David Howells <dhowells@redhat.com> |
FS-Cache: Recruit a page flags for cache management Recruit a page flag to aid in cache management. The following extra flag is defined: (1) PG_fscache (PG_private_2) The marked page is backed by a local cache and is pinning resources in the cache driver. If PG_fscache is set, then things that checked for PG_private will now also check for that. This includes things like truncation and page invalidation. The function page_has_private() had been added to make the checks for both PG_private and PG_private_2 at the same time. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
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#
327c0e96 |
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31-Mar-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
vmscan: fix it to take care of nodemask try_to_free_pages() is used for the direct reclaim of up to SWAP_CLUSTER_MAX pages when watermarks are low. The caller to alloc_pages_nodemask() can specify a nodemask of nodes that are allowed to be used but this is not passed to try_to_free_pages(). This can lead to unnecessary reclaim of pages that are unusable by the caller and int the worst case lead to allocation failure as progress was not been make where it is needed. This patch passes the nodemask used for alloc_pages_nodemask() to try_to_free_pages(). Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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88c3bd70 |
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31-Mar-2009 |
David Rientjes <rientjes@google.com> |
vmscan: print shrink_slab symbol name on negative shrinker objects When a shrinker has a negative number of objects to delete, the symbol name of the shrinker should be printed, not shrink_slab. This also makes the error message slightly more informative. Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ad1c3544 |
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31-Mar-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: don't free swap slots on page deactivation The pagevec_swap_free() at the end of shrink_active_list() was introduced in 68a22394 "vmscan: free swap space on swap-in/activation" when shrink_active_list() was still rotating referenced active pages. In 7e9cd48 "vmscan: fix pagecache reclaim referenced bit check" this was changed, the rotating removed but the pagevec_swap_free() after the rotation loop was forgotten, applying now to the pagevec of the deactivation loop instead. Now swap space is freed for deactivated pages. And only for those that happen to be on the pagevec after the deactivation loop. Complete 7e9cd48 and remove the rest of the swap freeing. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2443462b |
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31-Mar-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: move pagevec stripping to save unlock-relock In shrink_active_list() after the deactivation loop, we strip buffer heads from the potentially remaining pages in the pagevec. Currently, this drops the zone's lru lock for stripping, only to reacquire it again afterwards to update statistics. It is not necessary to strip the pages before updating the stats, so move the whole thing out of the protected region and save the extra locking. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: MinChan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bd2f6199 |
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31-Mar-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: respect higher order in zone_reclaim() During page allocation, there are two stages of direct reclaim that are applied to each zone in the preferred list. The first stage using zone_reclaim() reclaims unmapped file backed pages and slab pages if over defined limits as these are cheaper to reclaim. The caller specifies the order of the target allocation but the scan control is not being correctly initialised. The impact is that the correct number of pages are being reclaimed but that lumpy reclaim is not being applied. This increases the chances of a full direct reclaim via try_to_free_pages() is required. This patch initialises the order field of the scan control as requested by the caller. [mel@csn.ul.ie: rewrote changelog] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9786bf84 |
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31-Mar-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: clip swap_cluster_max in shrink_all_memory() shrink_inactive_list() scans in sc->swap_cluster_max chunks until it hits the scan limit it was passed. shrink_inactive_list() { do { isolate_pages(swap_cluster_max) shrink_page_list() } while (nr_scanned < max_scan); } This assumes that swap_cluster_max is not bigger than the scan limit because the latter is checked only after at least one iteration. In shrink_all_memory() sc->swap_cluster_max is initialized to the overall reclaim goal in the beginning but not decreased while reclaim is making progress which leads to subsequent calls to shrink_inactive_list() reclaiming way too much in the one iteration that is done unconditionally. Set sc->swap_cluster_max always to the proper goal before doing shrink_all_zones() shrink_list() shrink_inactive_list(). While the current shrink_all_memory() happily reclaims more than actually requested, this patch fixes it to never exceed the goal: unpatched wanted=10000 reclaimed=13356 wanted=10000 reclaimed=19711 wanted=10000 reclaimed=10289 wanted=10000 reclaimed=17306 wanted=10000 reclaimed=10700 wanted=10000 reclaimed=10004 wanted=10000 reclaimed=13301 wanted=10000 reclaimed=10976 wanted=10000 reclaimed=10605 wanted=10000 reclaimed=10088 wanted=10000 reclaimed=15000 patched wanted=10000 reclaimed=10000 wanted=10000 reclaimed=9599 wanted=10000 reclaimed=8476 wanted=10000 reclaimed=8326 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=9919 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=9624 wanted=10000 reclaimed=10000 wanted=10000 reclaimed=10000 wanted=8500 reclaimed=8092 wanted=316 reclaimed=316 Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: MinChan Kim <minchan.kim@gmail.com> Acked-by: Nigel Cunningham <ncunningham@crca.org.au> Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d979677c |
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31-Mar-2009 |
MinChan Kim <minchan.kim@gmail.com> |
mm: shrink_all_memory(): use sc.nr_reclaimed Commit a79311c14eae4bb946a97af25f3e1b17d625985d "vmscan: bail out of direct reclaim after swap_cluster_max pages" moved the nr_reclaimed counter into the scan control to accumulate the number of all reclaimed pages in a reclaim invocation. shrink_all_memory() can use the same mechanism. it increase code consistency and redability. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: MinChan Kim <minchan.kim@gmail.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ee99c71c |
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31-Mar-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: introduce for_each_populated_zone() macro Impact: cleanup In almost cases, for_each_zone() is used with populated_zone(). It's because almost function doesn't need memoryless node information. Therefore, for_each_populated_zone() can help to make code simplify. This patch has no functional change. [akpm@linux-foundation.org: small cleanup] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a6dc60f8 |
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31-Mar-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
vmscan: rename sc.may_swap to may_unmap sc.may_swap does not only influence reclaiming of anon pages but pages mapped into pagetables in general, which also includes mapped file pages. In shrink_page_list(): if (!sc->may_swap && page_mapped(page)) goto keep_locked; For anon pages, this makes sense as they are always mapped and reclaiming them always requires swapping. But mapped file pages are skipped here as well and it has nothing to do with swapping. The real effect of the knob is whether mapped pages are unmapped and reclaimed or not. Rename it to `may_unmap' to have its name match its actual meaning more precisely. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: MinChan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1d885526 |
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13-Mar-2009 |
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> |
vmscan: pgmoved should be cleared after updating recent_rotated pgmoved should be cleared after updating recent_rotated. Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a70f7302 |
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12-Mar-2009 |
Rusty Russell <rusty@rustcorp.com.au> |
cpumask: replace node_to_cpumask with cpumask_of_node. Impact: cleanup node_to_cpumask (and the blecherous node_to_cpumask_ptr which contained a declaration) are replaced now everyone implements cpumask_of_node. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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#
f272b7bc |
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12-Mar-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: use correct scan number at reclaim Even when page reclaim is under mem_cgroup, # of scan page is determined by status of global LRU. Fix that. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0cb57258 |
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13-Feb-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
swsusp: clean up shrink_all_zones() Move local variables to innermost possible scopes and use local variables to cache calculations/reads done more than once. No change in functionality (intended). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Len Brown <lenb@kernel.org> Cc: Greg KH <gregkh@suse.de> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3049103d |
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13-Feb-2009 |
Johannes Weiner <hannes@cmpxchg.org> |
swsusp: dont fiddle with swappiness sc.swappiness is not used in the swsusp memory shrinking path, do not set it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Len Brown <lenb@kernel.org> Cc: Greg KH <gregkh@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6700ec65 |
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15-Feb-2009 |
Ingo Molnar <mingo@elte.hu> |
lockdep: annotate reclaim context (__GFP_NOFS), fix Impact: fix build warning Fix: mm/vmscan.c: In function ‘kswapd’: mm/vmscan.c:1969: warning: ISO C90 forbids mixed declarations and code node_to_cpumask_ptr(cpumask, pgdat->node_id), has a side-effect: it defines the 'cpumask' local variable as well, so it has to go into the variable definition section. Sidenote: it might make sense to make this purpose of these macros more apparent, by naming them the standard way, such as: DEFINE_node_to_cpumask_ptr(cpumask, pgdat->node_id); (But that is outside the scope of this patch.) Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Mike Travis <travis@sgi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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cf40bd16 |
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21-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
lockdep: annotate reclaim context (__GFP_NOFS) Here is another version, with the incremental patch rolled up, and added reclaim context annotation to kswapd, and allocation tracing to slab allocators (which may only ever reach the page allocator in rare cases, so it is good to put annotations here too). Haven't tested this version as such, but it should be getting closer to merge worthy ;) -- After noticing some code in mm/filemap.c accidentally perform a __GFP_FS allocation when it should not have been, I thought it might be a good idea to try to catch this kind of thing with lockdep. I coded up a little idea that seems to work. Unfortunately the system has to actually be in __GFP_FS page reclaim, then take the lock, before it will mark it. But at least that might still be some orders of magnitude more common (and more debuggable) than an actual deadlock condition, so we have some improvement I hope (the concept is no less complete than discovery of a lock's interrupt contexts). I guess we could even do the same thing with __GFP_IO (normal reclaim), and even GFP_NOIO locks too... but filesystems will have the most locks and fiddly code paths, so let's start there and see how it goes. It *seems* to work. I did a quick test. ================================= [ INFO: inconsistent lock state ] 2.6.28-rc6-00007-ged31348-dirty #26 --------------------------------- inconsistent {in-reclaim-W} -> {ov-reclaim-W} usage. modprobe/8526 [HC0[0]:SC0[0]:HE1:SE1] takes: (testlock){--..}, at: [<ffffffffa0020055>] brd_init+0x55/0x216 [brd] {in-reclaim-W} state was registered at: [<ffffffff80267bdb>] __lock_acquire+0x75b/0x1a60 [<ffffffff80268f71>] lock_acquire+0x91/0xc0 [<ffffffff8070f0e1>] mutex_lock_nested+0xb1/0x310 [<ffffffffa002002b>] brd_init+0x2b/0x216 [brd] [<ffffffff8020903b>] _stext+0x3b/0x170 [<ffffffff80272ebf>] sys_init_module+0xaf/0x1e0 [<ffffffff8020c3fb>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff irq event stamp: 3929 hardirqs last enabled at (3929): [<ffffffff8070f2b5>] mutex_lock_nested+0x285/0x310 hardirqs last disabled at (3928): [<ffffffff8070f089>] mutex_lock_nested+0x59/0x310 softirqs last enabled at (3732): [<ffffffff8061f623>] sk_filter+0x83/0xe0 softirqs last disabled at (3730): [<ffffffff8061f5b6>] sk_filter+0x16/0xe0 other info that might help us debug this: 1 lock held by modprobe/8526: #0: (testlock){--..}, at: [<ffffffffa0020055>] brd_init+0x55/0x216 [brd] stack backtrace: Pid: 8526, comm: modprobe Not tainted 2.6.28-rc6-00007-ged31348-dirty #26 Call Trace: [<ffffffff80265483>] print_usage_bug+0x193/0x1d0 [<ffffffff80266530>] mark_lock+0xaf0/0xca0 [<ffffffff80266735>] mark_held_locks+0x55/0xc0 [<ffffffffa0020000>] ? brd_init+0x0/0x216 [brd] [<ffffffff802667ca>] trace_reclaim_fs+0x2a/0x60 [<ffffffff80285005>] __alloc_pages_internal+0x475/0x580 [<ffffffff8070f29e>] ? mutex_lock_nested+0x26e/0x310 [<ffffffffa0020000>] ? brd_init+0x0/0x216 [brd] [<ffffffffa002006a>] brd_init+0x6a/0x216 [brd] [<ffffffffa0020000>] ? brd_init+0x0/0x216 [brd] [<ffffffff8020903b>] _stext+0x3b/0x170 [<ffffffff8070f8b9>] ? mutex_unlock+0x9/0x10 [<ffffffff8070f83d>] ? __mutex_unlock_slowpath+0x10d/0x180 [<ffffffff802669ec>] ? trace_hardirqs_on_caller+0x12c/0x190 [<ffffffff80272ebf>] sys_init_module+0xaf/0x1e0 [<ffffffff8020c3fb>] system_call_fastpath+0x16/0x1b Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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c772be93 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: fix calculation of active_ratio Currently, inactive_ratio of memcg is calculated at setting limit. because page_alloc.c does so and current implementation is straightforward porting. However, memcg introduced hierarchy feature recently. In hierarchy restriction, memory limit is not only decided memory.limit_in_bytes of current cgroup, but also parent limit and sibling memory usage. Then, The optimal inactive_ratio is changed frequently. So, everytime calculation is better. Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a7885eb8 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: swappiness Currently, /proc/sys/vm/swappiness can change swappiness ratio for global reclaim. However, memcg reclaim doesn't have tuning parameter for itself. In general, the optimal swappiness depend on workload. (e.g. hpc workload need to low swappiness than the others.) Then, per cgroup swappiness improve administrator tunability. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e72e2bd6 |
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07-Jan-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: rename scan global lru Rename scan_global_lru() to scanning_global_lru(). Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9439c1c9 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: remove mem_cgroup_cal_reclaim() Now, get_scan_ratio() return correct value although memcg reclaim. Then, mem_cgroup_calc_reclaim() can be removed. So, memcg reclaim get the same capability of anon/file reclaim balancing as global reclaim now. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3e2f41f1 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: add zone_reclaim_stat Introduce mem_cgroup_per_zone::reclaim_stat member and its statics collecting function. Now, get_scan_ratio() can calculate correct value on memcg reclaim. [hugh@veritas.com: avoid reclaim_stat oops when disabled] Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a3d8e054 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: add mem_cgroup_zone_nr_pages() Introduce mem_cgroup_zone_nr_pages(). It is called by zone_nr_pages() helper function. This patch doesn't have any behavior change. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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14797e23 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: add inactive_anon_is_low() The inactive_anon_is_low() is key component of active/inactive anon balancing on reclaim. However current inactive_anon_is_low() function only consider global reclaim. Therefore, we need following ugly scan_global_lru() condition. if (lru == LRU_ACTIVE_ANON && (!scan_global_lru(sc) || inactive_anon_is_low(zone))) { shrink_active_list(nr_to_scan, zone, sc, priority, file); return 0; it cause that memcg reclaim always deactivate pages when shrink_list() is called. To make mem_cgroup_inactive_anon_is_low() improve active/inactive anon balancing of memcgroup. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: "Pekka Enberg" <penberg@cs.helsinki.fi> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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eeee9a8c |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: make get_scan_ratio() safe for memcg Currently, get_scan_ratio() always calculate the balancing value for global reclaim and memcg reclaim doesn't use it. Therefore it doesn't have scan_global_lru() condition. However, we plan to expand get_scan_ratio() to be usable for memcg too, latter. Then, The dependency code of global reclaim in the get_scan_ratio() insert into scan_global_lru() condision explictly. This patch doesn't have any functional change. Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c9f299d9 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: add zone nr_pages helper function Add zone_nr_pages() helper function. It is used by a later patch. This patch doesn't have any functional change. Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6e901571 |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: introduce zone_reclaim struct Add zone_reclam_stat struct for later enhancement. A later patch uses this. This patch doesn't any behavior change (yet). Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f89eb90e |
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07-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
inactive_anon_is_low: move to vmscan The inactive_anon_is_low() is called only vmscan. Then it can move to vmscan.c This patch doesn't have any functional change. Reviewd-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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08e552c6 |
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07-Jan-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: synchronized LRU A big patch for changing memcg's LRU semantics. Now, - page_cgroup is linked to mem_cgroup's its own LRU (per zone). - LRU of page_cgroup is not synchronous with global LRU. - page and page_cgroup is one-to-one and statically allocated. - To find page_cgroup is on what LRU, you have to check pc->mem_cgroup as - lru = page_cgroup_zoneinfo(pc, nid_of_pc, zid_of_pc); - SwapCache is handled. And, when we handle LRU list of page_cgroup, we do following. pc = lookup_page_cgroup(page); lock_page_cgroup(pc); .....................(1) mz = page_cgroup_zoneinfo(pc); spin_lock(&mz->lru_lock); .....add to LRU spin_unlock(&mz->lru_lock); unlock_page_cgroup(pc); But (1) is spin_lock and we have to be afraid of dead-lock with zone->lru_lock. So, trylock() is used at (1), now. Without (1), we can't trust "mz" is correct. This is a trial to remove this dirty nesting of locks. This patch changes mz->lru_lock to be zone->lru_lock. Then, above sequence will be written as spin_lock(&zone->lru_lock); # in vmscan.c or swap.c via global LRU mem_cgroup_add/remove/etc_lru() { pc = lookup_page_cgroup(page); mz = page_cgroup_zoneinfo(pc); if (PageCgroupUsed(pc)) { ....add to LRU } spin_lock(&zone->lru_lock); # in vmscan.c or swap.c via global LRU This is much simpler. (*) We're safe even if we don't take lock_page_cgroup(pc). Because.. 1. When pc->mem_cgroup can be modified. - at charge. - at account_move(). 2. at charge the PCG_USED bit is not set before pc->mem_cgroup is fixed. 3. at account_move() the page is isolated and not on LRU. Pros. - easy for maintenance. - memcg can make use of laziness of pagevec. - we don't have to duplicated LRU/Active/Unevictable bit in page_cgroup. - LRU status of memcg will be synchronized with global LRU's one. - # of locks are reduced. - account_move() is simplified very much. Cons. - may increase cost of LRU rotation. (no impact if memcg is not configured.) Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8c7c6e34 |
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07-Jan-2009 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memcg: mem+swap controller core This patch implements per cgroup limit for usage of memory+swap. However there are SwapCache, double counting of swap-cache and swap-entry is avoided. Mem+Swap controller works as following. - memory usage is limited by memory.limit_in_bytes. - memory + swap usage is limited by memory.memsw_limit_in_bytes. This has following benefits. - A user can limit total resource usage of mem+swap. Without this, because memory resource controller doesn't take care of usage of swap, a process can exhaust all the swap (by memory leak.) We can avoid this case. And Swap is shared resource but it cannot be reclaimed (goes back to memory) until it's used. This characteristic can be trouble when the memory is divided into some parts by cpuset or memcg. Assume group A and group B. After some application executes, the system can be.. Group A -- very large free memory space but occupy 99% of swap. Group B -- under memory shortage but cannot use swap...it's nearly full. Ability to set appropriate swap limit for each group is required. Maybe someone wonder "why not swap but mem+swap ?" - The global LRU(kswapd) can swap out arbitrary pages. Swap-out means to move account from memory to swap...there is no change in usage of mem+swap. In other words, when we want to limit the usage of swap without affecting global LRU, mem+swap limit is better than just limiting swap. Accounting target information is stored in swap_cgroup which is per swap entry record. Charge is done as following. map - charge page and memsw. unmap - uncharge page/memsw if not SwapCache. swap-out (__delete_from_swap_cache) - uncharge page - record mem_cgroup information to swap_cgroup. swap-in (do_swap_page) - charged as page and memsw. record in swap_cgroup is cleared. memsw accounting is decremented. swap-free (swap_free()) - if swap entry is freed, memsw is uncharged by PAGE_SIZE. There are people work under never-swap environments and consider swap as something bad. For such people, this mem+swap controller extension is just an overhead. This overhead is avoided by config or boot option. (see Kconfig. detail is not in this patch.) TODO: - maybe more optimization can be don in swap-in path. (but not very safe.) But we just do simple accounting at this stage. [nishimura@mxp.nes.nec.co.jp: make resize limit hold mutex] [hugh@veritas.com: memswap controller core swapcache fixes] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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73ce02e9 |
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06-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: stop kswapd's infinite loop at high order allocation Wassim Dagash reported following kswapd infinite loop problem. kswapd runs in some infinite loop trying to swap until order 10 of zone highmem is OK.... kswapd will continue to try to balance order 10 of zone highmem forever (or until someone release a very large chunk of highmem). For non order-0 allocations, the system may never be balanced due to fragmentation but kswapd should not infinitely loop as a result. Instead, recheck all watermarks at order-0 as they are the most important. If watermarks are ok, kswapd will go back to sleep. [akpm@linux-foundation.org: fix comment] Reported-by: wassim dagash <wassim.dagash@gmail.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b555749a |
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06-Jan-2009 |
Andrew Morton <akpm@linux-foundation.org> |
vmscan: shrink_active_list(): reduce lru_lock hold time These three statements manipulate local variables and do not need the lock coverage. Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Rik van Riel <riel@redhat.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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09f445e7 |
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06-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: kill zone_is_near_oom() zone_is_near_oom() is unused. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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01dbe5c9 |
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06-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
vmscan: improve reclaim throughput to bail out patch The vmscan bail out patch move nr_reclaimed variable to struct scan_control. Unfortunately, indirect access can easily happen cache miss. if heavy memory pressure happend, that's ok. cache miss already plenty. it is not observable. but, if memory pressure is lite, performance degression is obserbable. I compared following three pattern (it was mesured 10 times each) hackbench 125 process 3000 hackbench 130 process 3000 hackbench 135 process 3000 2.6.28-rc6 bail-out 125 130 135 125 130 135 ============================================================== 71.866 75.86 81.274 93.414 73.254 193.382 74.145 78.295 77.27 74.897 75.021 80.17 70.305 77.643 75.855 70.134 77.571 79.896 74.288 73.986 75.955 77.222 78.48 80.619 72.029 79.947 78.312 75.128 82.172 79.708 71.499 77.615 77.042 74.177 76.532 77.306 76.188 74.471 83.562 73.839 72.43 79.833 73.236 75.606 78.743 76.001 76.557 82.726 69.427 77.271 76.691 76.236 79.371 103.189 72.473 76.978 80.643 69.128 78.932 75.736 avg 72.545 76.767 78.534 76.017 77.03 93.256 std 1.89 1.71 2.41 6.29 2.79 34.16 min 69.427 73.986 75.855 69.128 72.43 75.736 max 76.188 79.947 83.562 93.414 82.172 193.382 about 4-5% degression. Then, this patch introduces a temporary local variable. result: 2.6.28-rc6 this patch num 125 130 135 125 130 135 ============================================================== 71.866 75.86 81.274 67.302 68.269 77.161 74.145 78.295 77.27 72.616 72.712 79.06 70.305 77.643 75.855 72.475 75.712 77.735 74.288 73.986 75.955 69.229 73.062 78.814 72.029 79.947 78.312 71.551 74.392 78.564 71.499 77.615 77.042 69.227 74.31 78.837 76.188 74.471 83.562 70.759 75.256 76.6 73.236 75.606 78.743 69.966 76.001 78.464 69.427 77.271 76.691 69.068 75.218 80.321 72.473 76.978 80.643 72.057 77.151 79.068 avg 72.545 76.767 78.534 70.425 74.2083 78.462 std 1.89 1.71 2.41 1.66 2.34 1.00 min 69.427 73.986 75.855 67.302 68.269 76.6 max 76.188 79.947 83.562 72.616 77.151 80.321 OK. the degression is disappeared. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a79311c1 |
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06-Jan-2009 |
Rik van Riel <riel@redhat.com> |
vmscan: bail out of direct reclaim after swap_cluster_max pages When the VM is under pressure, it can happen that several direct reclaim processes are in the pageout code simultaneously. It also happens that the reclaiming processes run into mostly referenced, mapped and dirty pages in the first round. This results in multiple direct reclaim processes having a lower pageout priority, which corresponds to a higher target of pages to scan. This in turn can result in each direct reclaim process freeing many pages. Together, they can end up freeing way too many pages. This kicks useful data out of memory (in some cases more than half of all memory is swapped out). It also impacts performance by keeping tasks stuck in the pageout code for too long. A 30% improvement in hackbench has been observed with this patch. The fix is relatively simple: in shrink_zone() we can check how many pages we have already freed, direct reclaim tasks break out of the scanning loop if they have already freed enough pages and have reached a lower priority level. We do not break out of shrink_zone() when priority == DEF_PRIORITY, to ensure that equal pressure is applied to every zone in the common case. However, in order to do this we do need to know how many pages we already freed, so move nr_reclaimed into scan_control. akpm: a historical interlude... We tried this in 2004: :commit e468e46a9bea3297011d5918663ce6d19094cf87 :Author: akpm <akpm> :Date: Thu Jun 24 15:53:52 2004 +0000 : :[PATCH] vmscan.c: dont reclaim too many pages : : The shrink_zone() logic can, under some circumstances, cause far too many : pages to be reclaimed. Say, we're scanning at high priority and suddenly hit : a large number of reclaimable pages on the LRU. : Change things so we bale out when SWAP_CLUSTER_MAX pages have been reclaimed. And we reverted it in 2006: :commit 210fe530305ee50cd889fe9250168228b2994f32 :Author: Andrew Morton <akpm@osdl.org> :Date: Fri Jan 6 00:11:14 2006 -0800 : : [PATCH] vmscan: balancing fix : : Revert a patch which went into 2.6.8-rc1. The changelog for that patch was: : : The shrink_zone() logic can, under some circumstances, cause far too many : pages to be reclaimed. Say, we're scanning at high priority and suddenly : hit a large number of reclaimable pages on the LRU. : : Change things so we bale out when SWAP_CLUSTER_MAX pages have been : reclaimed. : : Problem is, this change caused significant imbalance in inter-zone scan : balancing by truncating scans of larger zones. : : Suppose, for example, ZONE_HIGHMEM is 10x the size of ZONE_NORMAL. The zone : balancing algorithm would require that if we're scanning 100 pages of : ZONE_HIGHMEM, we should scan 10 pages of ZONE_NORMAL. But this logic will : cause the scanning of ZONE_HIGHMEM to bale out after only 32 pages are : reclaimed. Thus effectively causing smaller zones to be scanned relatively : harder than large ones. : : Now I need to remember what the workload was which caused me to write this : patch originally, then fix it up in a different way... And we haven't demonstrated that whatever problem caused that reversion is not being reintroduced by this change in 2008. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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14b90b22 |
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06-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: make scan_zone_unevictable_pages() static sparse output following warning mm/vmscan.c:2507:6: warning: symbol 'scan_zone_unevictable_pages' was not declared. Should it be static? cleanup here. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ff30153b |
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06-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: make scan_all_zones_unevictable_pages() static sparse output following warning. mm/vmscan.c:2549:6: warning: symbol 'scan_all_zones_unevictable_pages' was not declared. Should it be static? cleanup here. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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077cbc58 |
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06-Jan-2009 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
memcg: reclaim shouldn't change zone->recent_rotated statistics memcg reclaim shouldn't change zone->recent_rotated statistics. If memcgroup reclaim changes zone statistics, global reclaim can get a bit confused. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b962716b |
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06-Jan-2009 |
Hugh Dickins <hugh@veritas.com> |
mm: optimize get_scan_ratio for no swap Rik suggests a simplified get_scan_ratio() for !CONFIG_SWAP. Yes, the gcc optimizer gives us that, when nr_swap_pages is #defined as 0L. Move usual declaration to swapfile.c: it never belonged in page_alloc.c. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Robin Holt <holt@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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60371d97 |
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06-Jan-2009 |
Hugh Dickins <hugh@veritas.com> |
mm: add add_to_swap stub If we add a failing stub for add_to_swap(), then we can remove the #ifdef CONFIG_SWAP from mm/vmscan.c. This was intended as a source cleanup, but looking more closely, it turns out that the !CONFIG_SWAP case was going to keep_locked for an anonymous page, whereas now it goes to the more suitable activate_locked, like the CONFIG_SWAP nr_swap_pages 0 case. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Robin Holt <holt@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ac47b003 |
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06-Jan-2009 |
Hugh Dickins <hugh@veritas.com> |
mm: remove gfp_mask from add_to_swap Remove gfp_mask argument from add_to_swap(): it's misleading because its only caller, shrink_page_list(), is not atomic at that point; and in due course (implementing discard) we'll sometimes want to allocate some memory with GFP_NOIO (as is used in swap_writepage) when allocating swap. No change to the gfp_mask passed down to add_to_swap_cache(): still use __GFP_HIGH without __GFP_WAIT (with nomemalloc and nowarn as before): though it's not obvious if that's the best combination to ask for here. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Robin Holt <holt@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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63d6c5ad |
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06-Jan-2009 |
Hugh Dickins <hugh@veritas.com> |
mm: remove try_to_munlock from vmscan An unfortunate feature of the Unevictable LRU work was that reclaiming an anonymous page involved an extra scan through the anon_vma: to check that the page is evictable before allocating swap, because the swap could not be freed reliably soon afterwards. Now try_to_free_swap() has replaced remove_exclusive_swap_page(), that's not an issue any more: remove try_to_munlock() call from shrink_page_list(), leaving it to try_to_munmap() to discover if the page is one to be culled to the unevictable list - in which case then try_to_free_swap(). Update unevictable-lru.txt to remove comments on the try_to_munlock() in shrink_page_list(), and shorten some lines over 80 columns. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Robin Holt <holt@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a2c43eed |
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06-Jan-2009 |
Hugh Dickins <hugh@veritas.com> |
mm: try_to_free_swap replaces remove_exclusive_swap_page remove_exclusive_swap_page(): its problem is in living up to its name. It doesn't matter if someone else has a reference to the page (raised page_count); it doesn't matter if the page is mapped into userspace (raised page_mapcount - though that hints it may be worth keeping the swap): all that matters is that there be no more references to the swap (and no writeback in progress). swapoff (try_to_unuse) has been removing pages from swapcache for years, with no concern for page count or page mapcount, and we used to have a comment in lookup_swap_cache() recognizing that: if you go for a page of swapcache, you'll get the right page, but it could have been removed from swapcache by the time you get page lock. So, give up asking for exclusivity: get rid of remove_exclusive_swap_page(), and remove_exclusive_swap_page_ref() and remove_exclusive_swap_page_count() which were spawned for the recent LRU work: replace them by the simpler try_to_free_swap() which just checks page_swapcount(). Similarly, remove the page_count limitation from free_swap_and_count(), but assume that it's worth holding on to the swap if page is mapped and swap nowhere near full. Add a vm_swap_full() test in free_swap_cache()? It would be consistent, but I think we probably have enough for now. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Robin Holt <holt@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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174596a0 |
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31-Dec-2008 |
Rusty Russell <rusty@rustcorp.com.au> |
cpumask: convert mm/ Impact: Use new API Convert kernel mm functions to use struct cpumask. We skip include/linux/percpu.h and mm/allocpercpu.c, which are in flux. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com> Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
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3e597945 |
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31-Dec-2008 |
Rusty Russell <rusty@rustcorp.com.au> |
cpumask: remove any_online_cpu() users: mm/ Impact: Remove obsolete API usage any_online_cpu() is a good name, but it takes a cpumask_t, not a pointer. There are several places where any_online_cpu() doesn't really want a mask arg at all. Replace all callers with cpumask_any() and cpumask_any_and(). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com>
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2a1dc509 |
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30-Nov-2008 |
Johannes Weiner <hannes@saeurebad.de> |
vmscan: protect zone rotation stats by lru lock The zone's rotation statistics must not be accessed without the corresponding LRU lock held. Fix an unprotected write in shrink_active_list(). Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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00d8089c |
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19-Nov-2008 |
Rik van Riel <riel@redhat.com> |
vmscan: fix get_scan_ratio() comment Fix the old comment on the scan ratio calculations. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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63eb6b93 |
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19-Nov-2008 |
Hugh Dickins <hugh@veritas.com> |
vmscan: let GFP_NOFS go to swap again In the past, GFP_NOFS (but of course not GFP_NOIO) was allowed to reclaim by writing to swap. That got partially broken in 2.6.23, when may_enter_fs initialization was moved up before the allocation of swap, so its PageSwapCache test was failing the first time around, Fix it by setting may_enter_fs when add_to_swap() succeeds with __GFP_IO. In fact, check __GFP_IO before calling add_to_swap(): allocating swap we're not ready to use just increases disk seeking. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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748f1a2e |
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14-Nov-2008 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: remove unevictable's show_page_path Hugh Dickins reported show_page_path() is buggy and unsafe because - lack dput() against d_find_alias() - don't concern vma->vm_mm->owner == NULL - lack lock_page() it was only for debugging, so rather than trying to fix it, just remove it now. Reported-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> CC: Lee Schermerhorn <Lee.Schermerhorn@hp.com> CC: Rik van Riel <riel@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a978d6f5 |
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18-Oct-2008 |
Nick Piggin <npiggin@suse.de> |
mm: unlockless reclaim unlock_page is fairly expensive. It can be avoided in page reclaim success path. By definition if we have any other references to the page it would be a bug anyway. Signed-off-by: Nick Piggin <npiggin@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e0f79b8f |
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18-Oct-2008 |
Johannes Weiner <hannes@saeurebad.de> |
vmscan: don't accumulate scan pressure on unrelated lists During each reclaim scan we accumulate scan pressure on unrelated lists which will result in bogus scans and unwanted reclaims eventually. Scanning lists with few reclaim candidates results in a lot of rotation and therefor also disturbs the list balancing, putting even more pressure on the wrong lists. In a test-case with much streaming IO, and therefor a crowded inactive file page list, swapping started because a) anon pages were reclaimed after swap_cluster_max reclaim invocations -- nr_scan of this list has just accumulated b) active file pages were scanned because *their* nr_scan has also accumulated through the same logic. And this in return created a lot of rotation for file pages and resulted in a decrease of file list priority, again increasing the pressure on anon pages. The result was an evicted working set of anon pages while there were tons of inactive file pages that should have been taken instead. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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af936a16 |
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18-Oct-2008 |
Lee Schermerhorn <lee.schermerhorn@hp.com> |
vmscan: unevictable LRU scan sysctl This patch adds a function to scan individual or all zones' unevictable lists and move any pages that have become evictable onto the respective zone's inactive list, where shrink_inactive_list() will deal with them. Adds sysctl to scan all nodes, and per node attributes to individual nodes' zones. Kosaki: If evictable page found in unevictable lru when write /proc/sys/vm/scan_unevictable_pages, print filename and file offset of these pages. [akpm@linux-foundation.org: fix one CONFIG_MMU=n build error] [kosaki.motohiro@jp.fujitsu.com: adapt vmscan-unevictable-lru-scan-sysctl.patch to new sysfs API] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b291f000 |
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18-Oct-2008 |
Nick Piggin <npiggin@suse.de> |
mlock: mlocked pages are unevictable Make sure that mlocked pages also live on the unevictable LRU, so kswapd will not scan them over and over again. This is achieved through various strategies: 1) add yet another page flag--PG_mlocked--to indicate that the page is locked for efficient testing in vmscan and, optionally, fault path. This allows early culling of unevictable pages, preventing them from getting to page_referenced()/try_to_unmap(). Also allows separate accounting of mlock'd pages, as Nick's original patch did. Note: Nick's original mlock patch used a PG_mlocked flag. I had removed this in favor of the PG_unevictable flag + an mlock_count [new page struct member]. I restored the PG_mlocked flag to eliminate the new count field. 2) add the mlock/unevictable infrastructure to mm/mlock.c, with internal APIs in mm/internal.h. This is a rework of Nick's original patch to these files, taking into account that mlocked pages are now kept on unevictable LRU list. 3) update vmscan.c:page_evictable() to check PageMlocked() and, if vma passed in, the vm_flags. Note that the vma will only be passed in for new pages in the fault path; and then only if the "cull unevictable pages in fault path" patch is included. 4) add try_to_unlock() to rmap.c to walk a page's rmap and ClearPageMlocked() if no other vmas have it mlocked. Reuses as much of try_to_unmap() as possible. This effectively replaces the use of one of the lru list links as an mlock count. If this mechanism let's pages in mlocked vmas leak through w/o PG_mlocked set [I don't know that it does], we should catch them later in try_to_unmap(). One hopes this will be rare, as it will be relatively expensive. Original mm/internal.h, mm/rmap.c and mm/mlock.c changes: Signed-off-by: Nick Piggin <npiggin@suse.de> splitlru: introduce __get_user_pages(): New munlock processing need to GUP_FLAGS_IGNORE_VMA_PERMISSIONS. because current get_user_pages() can't grab PROT_NONE pages theresore it cause PROT_NONE pages can't munlock. [akpm@linux-foundation.org: fix this for pagemap-pass-mm-into-pagewalkers.patch] [akpm@linux-foundation.org: untangle patch interdependencies] [akpm@linux-foundation.org: fix things after out-of-order merging] [hugh@veritas.com: fix page-flags mess] [lee.schermerhorn@hp.com: fix munlock page table walk - now requires 'mm'] [kosaki.motohiro@jp.fujitsu.com: build fix] [kosaki.motohiro@jp.fujitsu.com: fix truncate race and sevaral comments] [kosaki.motohiro@jp.fujitsu.com: splitlru: introduce __get_user_pages()] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Matt Mackall <mpm@selenic.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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89e004ea |
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18-Oct-2008 |
Lee Schermerhorn <Lee.Schermerhorn@hp.com> |
SHM_LOCKED pages are unevictable Shmem segments locked into memory via shmctl(SHM_LOCKED) should not be kept on the normal LRU, since scanning them is a waste of time and might throw off kswapd's balancing algorithms. Place them on the unevictable LRU list instead. Use the AS_UNEVICTABLE flag to mark address_space of SHM_LOCKed shared memory regions as unevictable. Then these pages will be culled off the normal LRU lists during vmscan. Add new wrapper function to clear the mapping's unevictable state when/if shared memory segment is munlocked. Add 'scan_mapping_unevictable_page()' to mm/vmscan.c to scan all pages in the shmem segment's mapping [struct address_space] for evictability now that they're no longer locked. If so, move them to the appropriate zone lru list. Changes depend on [CONFIG_]UNEVICTABLE_LRU. [kosaki.motohiro@jp.fujitsu.com: revert shm change] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ba9ddf49 |
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18-Oct-2008 |
Lee Schermerhorn <Lee.Schermerhorn@hp.com> |
Ramfs and Ram Disk pages are unevictable Christoph Lameter pointed out that ram disk pages also clutter the LRU lists. When vmscan finds them dirty and tries to clean them, the ram disk writeback function just redirties the page so that it goes back onto the active list. Round and round she goes... With the ram disk driver [rd.c] replaced by the newer 'brd.c', this is no longer the case, as ram disk pages are no longer maintained on the lru. [This makes them unmigratable for defrag or memory hot remove, but that can be addressed by a separate patch series.] However, the ramfs pages behave like ram disk pages used to, so: Define new address_space flag [shares address_space flags member with mapping's gfp mask] to indicate that the address space contains all unevictable pages. This will provide for efficient testing of ramfs pages in page_evictable(). Also provide wrapper functions to set/test the unevictable state to minimize #ifdefs in ramfs driver and any other users of this facility. Set the unevictable state on address_space structures for new ramfs inodes. Test the unevictable state in page_evictable() to cull unevictable pages. These changes depend on [CONFIG_]UNEVICTABLE_LRU. [riel@redhat.com: undo the brd.c part] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Debugged-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bbfd28ee |
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18-Oct-2008 |
Lee Schermerhorn <lee.schermerhorn@hp.com> |
unevictable lru: add event counting with statistics Fix to unevictable-lru-page-statistics.patch Add unevictable lru infrastructure vm events to the statistics patch. Rename the "NORECL_" and "noreclaim_" symbols and text strings to "UNEVICTABLE_" and "unevictable_", respectively. Currently, both the infrastructure and the mlocked pages event are added by a single patch later in the series. This makes it difficult to add or rework the incremental patches. The events actually "belong" with the stats, so pull them up to here. Also, restore the event counting to putback_lru_page(). This was removed from previous patch in series where it was "misplaced". The actual events weren't defined that early. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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894bc310 |
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18-Oct-2008 |
Lee Schermerhorn <Lee.Schermerhorn@hp.com> |
Unevictable LRU Infrastructure When the system contains lots of mlocked or otherwise unevictable pages, the pageout code (kswapd) can spend lots of time scanning over these pages. Worse still, the presence of lots of unevictable pages can confuse kswapd into thinking that more aggressive pageout modes are required, resulting in all kinds of bad behaviour. Infrastructure to manage pages excluded from reclaim--i.e., hidden from vmscan. Based on a patch by Larry Woodman of Red Hat. Reworked to maintain "unevictable" pages on a separate per-zone LRU list, to "hide" them from vmscan. Kosaki Motohiro added the support for the memory controller unevictable lru list. Pages on the unevictable list have both PG_unevictable and PG_lru set. Thus, PG_unevictable is analogous to and mutually exclusive with PG_active--it specifies which LRU list the page is on. The unevictable infrastructure is enabled by a new mm Kconfig option [CONFIG_]UNEVICTABLE_LRU. A new function 'page_evictable(page, vma)' in vmscan.c tests whether or not a page may be evictable. Subsequent patches will add the various !evictable tests. We'll want to keep these tests light-weight for use in shrink_active_list() and, possibly, the fault path. To avoid races between tasks putting pages [back] onto an LRU list and tasks that might be moving the page from non-evictable to evictable state, the new function 'putback_lru_page()' -- inverse to 'isolate_lru_page()' -- tests the "evictability" of a page after placing it on the LRU, before dropping the reference. If the page has become unevictable, putback_lru_page() will redo the 'putback', thus moving the page to the unevictable list. This way, we avoid "stranding" evictable pages on the unevictable list. [akpm@linux-foundation.org: fix fallout from out-of-order merge] [riel@redhat.com: fix UNEVICTABLE_LRU and !PROC_PAGE_MONITOR build] [nishimura@mxp.nes.nec.co.jp: remove redundant mapping check] [kosaki.motohiro@jp.fujitsu.com: unevictable-lru-infrastructure: putback_lru_page()/unevictable page handling rework] [kosaki.motohiro@jp.fujitsu.com: kill unnecessary lock_page() in vmscan.c] [kosaki.motohiro@jp.fujitsu.com: revert migration change of unevictable lru infrastructure] [kosaki.motohiro@jp.fujitsu.com: revert to unevictable-lru-infrastructure-kconfig-fix.patch] [kosaki.motohiro@jp.fujitsu.com: restore patch failure of vmstat-unevictable-and-mlocked-pages-vm-events.patch] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Debugged-by: Benjamin Kidwell <benjkidwell@yahoo.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
33c120ed |
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18-Oct-2008 |
Rik van Riel <riel@redhat.com> |
more aggressively use lumpy reclaim During an AIM7 run on a 16GB system, fork started failing around 32000 threads, despite the system having plenty of free swap and 15GB of pageable memory. This was on x86-64, so 8k stacks. If a higher order allocation fails, we can either: - keep evicting pages off the end of the LRUs and hope that we eventually create a contiguous region; this is somewhat unlikely if the system is under enough stress by new allocations - after trying normal eviction for a bit, use lumpy reclaim This patch switches the system to lumpy reclaim if the VM is having trouble freeing enough pages, using the same threshold for detection as used by pageout congestion wait. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
7e9cd484 |
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18-Oct-2008 |
Rik van Riel <riel@redhat.com> |
vmscan: fix pagecache reclaim referenced bit check Moving referenced pages back to the head of the active list creates a huge scalability problem, because by the time a large memory system finally runs out of free memory, every single page in the system will have been referenced. Not only do we not have the time to scan every single page on the active list, but since they have will all have the referenced bit set, that bit conveys no useful information. A more scalable solution is to just move every page that hits the end of the active list to the inactive list. We clear the referenced bit off of mapped pages, which need just one reference to be moved back onto the active list. Unmapped pages will be moved back to the active list after two references (see mark_page_accessed). We preserve the PG_referenced flag on unmapped pages to preserve accesses that were made while the page was on the active list. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
556adecb |
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18-Oct-2008 |
Rik van Riel <riel@redhat.com> |
vmscan: second chance replacement for anonymous pages We avoid evicting and scanning anonymous pages for the most part, but under some workloads we can end up with most of memory filled with anonymous pages. At that point, we suddenly need to clear the referenced bits on all of memory, which can take ages on very large memory systems. We can reduce the maximum number of pages that need to be scanned by not taking the referenced state into account when deactivating an anonymous page. After all, every anonymous page starts out referenced, so why check? If an anonymous page gets referenced again before it reaches the end of the inactive list, we move it back to the active list. To keep the maximum amount of necessary work reasonable, we scale the active to inactive ratio with the size of memory, using the formula active:inactive ratio = sqrt(memory in GB * 10). Kswapd CPU use now seems to scale by the amount of pageout bandwidth, instead of by the amount of memory present in the system. [kamezawa.hiroyu@jp.fujitsu.com: fix OOM with memcg] [kamezawa.hiroyu@jp.fujitsu.com: memcg: lru scan fix] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
4f98a2fe |
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18-Oct-2008 |
Rik van Riel <riel@redhat.com> |
vmscan: split LRU lists into anon & file sets Split the LRU lists in two, one set for pages that are backed by real file systems ("file") and one for pages that are backed by memory and swap ("anon"). The latter includes tmpfs. The advantage of doing this is that the VM will not have to scan over lots of anonymous pages (which we generally do not want to swap out), just to find the page cache pages that it should evict. This patch has the infrastructure and a basic policy to balance how much we scan the anon lists and how much we scan the file lists. The big policy changes are in separate patches. [lee.schermerhorn@hp.com: collect lru meminfo statistics from correct offset] [kosaki.motohiro@jp.fujitsu.com: prevent incorrect oom under split_lru] [kosaki.motohiro@jp.fujitsu.com: fix pagevec_move_tail() doesn't treat unevictable page] [hugh@veritas.com: memcg swapbacked pages active] [hugh@veritas.com: splitlru: BDI_CAP_SWAP_BACKED] [akpm@linux-foundation.org: fix /proc/vmstat units] [nishimura@mxp.nes.nec.co.jp: memcg: fix handling of shmem migration] [kosaki.motohiro@jp.fujitsu.com: adjust Quicklists field of /proc/meminfo] [kosaki.motohiro@jp.fujitsu.com: fix style issue of get_scan_ratio()] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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68a22394 |
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18-Oct-2008 |
Rik van Riel <riel@redhat.com> |
vmscan: free swap space on swap-in/activation If vm_swap_full() (swap space more than 50% full), the system will free swap space at swapin time. With this patch, the system will also free the swap space in the pageout code, when we decide that the page is not a candidate for swapout (and just wasting swap space). Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: MinChan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b69408e8 |
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18-Oct-2008 |
Christoph Lameter <cl@linux-foundation.org> |
vmscan: Use an indexed array for LRU variables Currently we are defining explicit variables for the inactive and active list. An indexed array can be more generic and avoid repeating similar code in several places in the reclaim code. We are saving a few bytes in terms of code size: Before: text data bss dec hex filename 4097753 573120 4092484 8763357 85b7dd vmlinux After: text data bss dec hex filename 4097729 573120 4092484 8763333 85b7c5 vmlinux Having an easy way to add new lru lists may ease future work on the reclaim code. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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62695a84 |
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18-Oct-2008 |
Nick Piggin <npiggin@suse.de> |
vmscan: move isolate_lru_page() to vmscan.c On large memory systems, the VM can spend way too much time scanning through pages that it cannot (or should not) evict from memory. Not only does it use up CPU time, but it also provokes lock contention and can leave large systems under memory presure in a catatonic state. This patch series improves VM scalability by: 1) putting filesystem backed, swap backed and unevictable pages onto their own LRUs, so the system only scans the pages that it can/should evict from memory 2) switching to two handed clock replacement for the anonymous LRUs, so the number of pages that need to be scanned when the system starts swapping is bound to a reasonable number 3) keeping unevictable pages off the LRU completely, so the VM does not waste CPU time scanning them. ramfs, ramdisk, SHM_LOCKED shared memory segments and mlock()ed VMA pages are keept on the unevictable list. This patch: isolate_lru_page logically belongs to be in vmscan.c than migrate.c. It is tough, because we don't need that function without memory migration so there is a valid argument to have it in migrate.c. However a subsequent patch needs to make use of it in the core mm, so we can happily move it to vmscan.c. Also, make the function a little more generic by not requiring that it adds an isolated page to a given list. Callers can do that. Note that we now have '__isolate_lru_page()', that does something quite different, visible outside of vmscan.c for use with memory controller. Methinks we need to rationalize these names/purposes. --lts [akpm@linux-foundation.org: fix mm/memory_hotplug.c build] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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529ae9aa |
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01-Aug-2008 |
Nick Piggin <npiggin@suse.de> |
mm: rename page trylock Converting page lock to new locking bitops requires a change of page flag operation naming, so we might as well convert it to something nicer (!TestSetPageLocked_Lock => trylock_page, SetPageLocked => set_page_locked). This also facilitates lockdeping of page lock. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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87547ee9 |
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29-Jul-2008 |
Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> |
do_try_to_free_page: update comments related to vmscan functions Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7d03431c |
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29-Jul-2008 |
Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> |
swapfile/vmscan: update comments related to vmscan functions Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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19fd6231 |
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25-Jul-2008 |
Nick Piggin <npiggin@suse.de> |
mm: spinlock tree_lock mapping->tree_lock has no read lockers. convert the lock from an rwlock to a spinlock. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e286781d |
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25-Jul-2008 |
Nick Piggin <npiggin@suse.de> |
mm: speculative page references If we can be sure that elevating the page_count on a pagecache page will pin it, we can speculatively run this operation, and subsequently check to see if we hit the right page rather than relying on holding a lock or otherwise pinning a reference to the page. This can be done if get_page/put_page behaves consistently throughout the whole tree (ie. if we "get" the page after it has been used for something else, we must be able to free it with a put_page). Actually, there is a period where the count behaves differently: when the page is free or if it is a constituent page of a compound page. We need an atomic_inc_not_zero operation to ensure we don't try to grab the page in either case. This patch introduces the core locking protocol to the pagecache (ie. adds page_cache_get_speculative, and tweaks some update-side code to make it work). Thanks to Hugh for pointing out an improvement to the algorithm setting page_count to zero when we have control of all references, in order to hold off speculative getters. [kamezawa.hiroyu@jp.fujitsu.com: fix migration_entry_wait()] [hugh@veritas.com: fix add_to_page_cache] [akpm@linux-foundation.org: repair a comment] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Jeff Garzik <jeff@garzik.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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873b4771 |
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25-Jul-2008 |
Keika Kobayashi <kobayashi.kk@ncos.nec.co.jp> |
per-task-delay-accounting: add memory reclaim delay Sometimes, application responses become bad under heavy memory load. Applications take a bit time to reclaim memory. The statistics, how long memory reclaim takes, will be useful to measure memory usage. This patch adds accounting memory reclaim to per-task-delay-accounting for accounting the time of do_try_to_free_pages(). <i.e> - When System is under low memory load, memory reclaim may not occur. $ free total used free shared buffers cached Mem: 8197800 1577300 6620500 0 4808 1516724 -/+ buffers/cache: 55768 8142032 Swap: 16386292 0 16386292 $ vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 5069748 10612 3014060 0 0 0 0 3 26 0 0 100 0 0 0 0 5069748 10612 3014060 0 0 0 0 4 22 0 0 100 0 0 0 0 5069748 10612 3014060 0 0 0 0 3 18 0 0 100 0 Measure the time of tar command. $ ls -s test.dat 1501472 test.dat $ time tar cvf test.tar test.dat real 0m13.388s user 0m0.116s sys 0m5.304s $ ./delayget -d -p <pid> CPU count real total virtual total delay total 428 5528345500 5477116080 62749891 IO count delay total 338 8078977189 SWAP count delay total 0 0 RECLAIM count delay total 0 0 - When system is under heavy memory load memory reclaim may occur. $ vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 7159032 49724 1812 3012 0 0 0 0 3 24 0 0 100 0 0 0 7159032 49724 1812 3012 0 0 0 0 4 24 0 0 100 0 0 0 7159032 49848 1812 3012 0 0 0 0 3 22 0 0 100 0 In this case, one process uses more 8G memory by execution of malloc() and memset(). $ time tar cvf test.tar test.dat real 1m38.563s <- increased by 85 sec user 0m0.140s sys 0m7.060s $ ./delayget -d -p <pid> CPU count real total virtual total delay total 9021 7140446250 7315277975 923201824 IO count delay total 8965 90466349669 SWAP count delay total 3 21036367 RECLAIM count delay total 740 61011951153 In the later case, the value of RECLAIM is increasing. So, taskstats can show how much memory reclaim influences TAT. Signed-off-by: Keika Kobayashi <kobayashi.kk@ncos.nec.co.jp> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujistu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c700be3d |
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12-Jun-2008 |
kosaki.motohiro@jp.fujitsu.com <kosaki.motohiro@jp.fujitsu.com> |
mm: fix incorrect variable type in do_try_to_free_pages() "Smarter retry of costly-order allocations" patch series change behaver of do_try_to_free_pages(). But unfortunately ret variable type was unchanged. Thus an overflow is possible. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d40cee24 |
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30-Apr-2008 |
Harvey Harrison <harvey.harrison@gmail.com> |
mm: remove remaining __FUNCTION__ occurrences __FUNCTION__ is gcc-specific, use __func__ Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a41f24ea |
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29-Apr-2008 |
Nishanth Aravamudan <nacc@us.ibm.com> |
page allocator: smarter retry of costly-order allocations Because of page order checks in __alloc_pages(), hugepage (and similarly large order) allocations will not retry unless explicitly marked __GFP_REPEAT. However, the current retry logic is nearly an infinite loop (or until reclaim does no progress whatsoever). For these costly allocations, that seems like overkill and could potentially never terminate. Mel observed that allowing current __GFP_REPEAT semantics for hugepage allocations essentially killed the system. I believe this is because we may continue to reclaim small orders of pages all over, but never have enough to satisfy the hugepage allocation request. This is clearly only a problem for large order allocations, of which hugepages are the most obvious (to me). Modify try_to_free_pages() to indicate how many pages were reclaimed. Use that information in __alloc_pages() to eventually fail a large __GFP_REPEAT allocation when we've reclaimed an order of pages equal to or greater than the allocation's order. This relies on lumpy reclaim functioning as advertised. Due to fragmentation, lumpy reclaim may not be able to free up the order needed in one invocation, so multiple iterations may be requred. In other words, the more fragmented memory is, the more retry attempts __GFP_REPEAT will make (particularly for higher order allocations). This changes the semantics of __GFP_REPEAT subtly, but *only* for allocations > PAGE_ALLOC_COSTLY_ORDER. With this patch, for those size allocations, we will try up to some point (at least 1<<order reclaimed pages), rather than forever (which is the case for allocations <= PAGE_ALLOC_COSTLY_ORDER). This change improves the /proc/sys/vm/nr_hugepages interface with a follow-on patch that makes pool allocations use __GFP_REPEAT. Rather than administrators repeatedly echo'ing a particular value into the sysctl, and forcing reclaim into action manually, this change allows for the sysctl to attempt a reasonable effort itself. Similarly, dynamic pool growth should be more successful under load, as lumpy reclaim can try to free up pages, rather than failing right away. Choosing to reclaim only up to the order of the requested allocation strikes a balance between not failing hugepage allocations and returning to the caller when it's unlikely to every succeed. Because of lumpy reclaim, if we have freed the order requested, hopefully it has been in big chunks and those chunks will allow our allocation to succeed. If that isn't the case after freeing up the current order, I don't think it is likely to succeed in the future, although it is possible given a particular fragmentation pattern. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Tested-by: Mel Gorman <mel@csn.ul.ie> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dd1a239f |
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28-Apr-2008 |
Mel Gorman <mel@csn.ul.ie> |
mm: have zonelist contains structs with both a zone pointer and zone_idx Filtering zonelists requires very frequent use of zone_idx(). This is costly as it involves a lookup of another structure and a substraction operation. As the zone_idx is often required, it should be quickly accessible. The node idx could also be stored here if it was found that accessing zone->node is significant which may be the case on workloads where nodemasks are heavily used. This patch introduces a struct zoneref to store a zone pointer and a zone index. The zonelist then consists of an array of these struct zonerefs which are looked up as necessary. Helpers are given for accessing the zone index as well as the node index. [kamezawa.hiroyu@jp.fujitsu.com: Suggested struct zoneref instead of embedding information in pointers] [hugh@veritas.com: mm-have-zonelist: fix memcg ooms] [hugh@veritas.com: just return do_try_to_free_pages] [hugh@veritas.com: do_try_to_free_pages gfp_mask redundant] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <clameter@sgi.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
54a6eb5c |
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28-Apr-2008 |
Mel Gorman <mel@csn.ul.ie> |
mm: use two zonelist that are filtered by GFP mask Currently a node has two sets of zonelists, one for each zone type in the system and a second set for GFP_THISNODE allocations. Based on the zones allowed by a gfp mask, one of these zonelists is selected. All of these zonelists consume memory and occupy cache lines. This patch replaces the multiple zonelists per-node with two zonelists. The first contains all populated zones in the system, ordered by distance, for fallback allocations when the target/preferred node has no free pages. The second contains all populated zones in the node suitable for GFP_THISNODE allocations. An iterator macro is introduced called for_each_zone_zonelist() that interates through each zone allowed by the GFP flags in the selected zonelist. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <clameter@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
dac1d27b |
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28-Apr-2008 |
Mel Gorman <mel@csn.ul.ie> |
mm: use zonelists instead of zones when direct reclaiming pages The following patches replace multiple zonelists per node with two zonelists that are filtered based on the GFP flags. The patches as a set fix a bug with regard to the use of MPOL_BIND and ZONE_MOVABLE. With this patchset, the MPOL_BIND will apply to the two highest zones when the highest zone is ZONE_MOVABLE. This should be considered as an alternative fix for the MPOL_BIND+ZONE_MOVABLE in 2.6.23 to the previously discussed hack that filters only custom zonelists. The first patch cleans up an inconsistency where direct reclaim uses zonelist->zones where other places use zonelist. The second patch introduces a helper function node_zonelist() for looking up the appropriate zonelist for a GFP mask which simplifies patches later in the set. The third patch defines/remembers the "preferred zone" for numa statistics, as it is no longer always the first zone in a zonelist. The forth patch replaces multiple zonelists with two zonelists that are filtered. The two zonelists are due to the fact that the memoryless patchset introduces a second set of zonelists for __GFP_THISNODE. The fifth patch introduces helper macros for retrieving the zone and node indices of entries in a zonelist. The final patch introduces filtering of the zonelists based on a nodemask. Two zonelists exist per node, one for normal allocations and one for __GFP_THISNODE. Performance results varied depending on the machine configuration. In real workloads the gain/loss will depend on how much the userspace portion of the benchmark benefits from having more cache available due to reduced referencing of zonelists. These are the range of performance losses/gains when running against 2.6.24-rc4-mm1. The set and these machines are a mix of i386, x86_64 and ppc64 both NUMA and non-NUMA. loss to gain Total CPU time on Kernbench: -0.86% to 1.13% Elapsed time on Kernbench: -0.79% to 0.76% page_test from aim9: -4.37% to 0.79% brk_test from aim9: -0.71% to 4.07% fork_test from aim9: -1.84% to 4.60% exec_test from aim9: -0.71% to 1.08% This patch: The allocator deals with zonelists which indicate the order in which zones should be targeted for an allocation. Similarly, direct reclaim of pages iterates over an array of zones. For consistency, this patch converts direct reclaim to use a zonelist. No functionality is changed by this patch. This simplifies zonelist iterators in the next patch. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <clameter@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c5f59f08 |
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04-Apr-2008 |
Mike Travis <travis@sgi.com> |
nodemask: use new node_to_cpumask_ptr function * Use new node_to_cpumask_ptr. This creates a pointer to the cpumask for a given node. This definition is in mm patch: asm-generic-add-node_to_cpumask_ptr-macro.patch * Use new set_cpus_allowed_ptr function. Depends on: [mm-patch]: asm-generic-add-node_to_cpumask_ptr-macro.patch [sched-devel]: sched: add new set_cpus_allowed_ptr function [x86/latest]: x86: add cpus_scnprintf function Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Greg Banks <gnb@melbourne.sgi.com> Cc: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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#
4dd4b920 |
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24-Mar-2008 |
Andrew Morton <akpm@linux-foundation.org> |
revert "kswapd should only wait on IO if there is IO" Revert commit f1a9ee758de7de1e040de849fdef46e6802ea117: Author: Rik van Riel <riel@redhat.com> Date: Thu Feb 7 00:14:08 2008 -0800 kswapd should only wait on IO if there is IO The current kswapd (and try_to_free_pages) code has an oddity where the code will wait on IO, even if there is no IO in flight. This problem is notable especially when the system scans through many unfreeable pages, causing unnecessary stalls in the VM. Additionally, tasks without __GFP_FS or __GFP_IO in the direct reclaim path will sleep if a significant number of pages are encountered that should be written out. This gives kswapd a chance to write out those pages, while the direct reclaim task sleeps. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Because of large latencies and interactivity problems reported by Carlos, here: http://lkml.org/lkml/2008/3/22/211 Cc: Rik van Riel <riel@redhat.com> Cc: "Carlos R. Mafra" <crmafra2@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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427d5416 |
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04-Mar-2008 |
Hugh Dickins <hugh@veritas.com> |
memcg: move_lists on page not page_cgroup Each caller of mem_cgroup_move_lists is having to use page_get_page_cgroup: it's more convenient if it acts upon the page itself not the page_cgroup; and in a later patch this becomes important to handle within memcontrol.c. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: David Rientjes <rientjes@google.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hirokazu Takahashi <taka@valinux.co.jp> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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00f0b825 |
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04-Mar-2008 |
Balbir Singh <balbir@linux.vnet.ibm.com> |
Memory controller: rename to Memory Resource Controller Rename Memory Controller to Memory Resource Controller. Reflect the same changes in the CONFIG definition for the Memory Resource Controller. Group together the config options for Resource Counters and Memory Resource Controller. Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1cfb419b |
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07-Feb-2008 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
per-zone and reclaim enhancements for memory controller: modifies vmscan.c for isolate globa/cgroup lru activity When using memory controller, there are 2 levels of memory reclaim. 1. zone memory reclaim because of system/zone memory shortage. 2. memory cgroup memory reclaim because of hitting limit. These two can be distinguished by sc->mem_cgroup parameter. (scan_global_lru() macro) This patch tries to make memory cgroup reclaim routine avoid affecting system/zone memory reclaim. This patch inserts if (scan_global_lru()) and hook to memory_cgroup reclaim support functions. This patch can be a help for isolating system lru activity and group lru activity and shows what additional functions are necessary. * mem_cgroup_calc_mapped_ratio() ... calculate mapped ratio for cgroup. * mem_cgroup_reclaim_imbalance() ... calculate active/inactive balance in cgroup. * mem_cgroup_calc_reclaim_active() ... calculate the number of active pages to be scanned in this priority in mem_cgroup. * mem_cgroup_calc_reclaim_inactive() ... calculate the number of inactive pages to be scanned in this priority in mem_cgroup. * mem_cgroup_all_unreclaimable() .. checks cgroup's page is all unreclaimable or not. * mem_cgroup_get_reclaim_priority() ... * mem_cgroup_note_reclaim_priority() ... record reclaim priority (temporal) * mem_cgroup_remember_reclaim_priority() .... record reclaim priority as zone->prev_priority. This value is used for calc reclaim_mapped. [akpm@linux-foundation.org: fix unused var warning] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Paul Menage <menage@google.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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91a45470 |
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07-Feb-2008 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
per-zone and reclaim enhancements for memory controller: add scan_global_lru macro This is used to detect which scan_control scans global lru or mem_cgroup lru. And compiled to be static value (1) when memory controller is not configured. This may make the meaning obvious. Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: David Rientjes <rientjes@google.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Paul Menage <menage@google.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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417eead3 |
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07-Feb-2008 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
memory cgroup enhancements: fix zone handling in try_to_free_mem_cgroup_page Because NODE_DATA(node)->node_zonelists[] is guaranteed to contain all necessary zones, it is not necessary to use for_each_online_node. And this for_each_online_node() makes reclaim routine start always from node 0. This is not good. This patch makes reclaim start from caller's node and just use usual (default) zonelist order. [akpm@linux-foundation.org: fix warning] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Paul Menage <menage@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Kirill Korotaev <dev@sw.ru> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: David Rientjes <rientjes@google.com> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f1a9ee75 |
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07-Feb-2008 |
Rik van Riel <riel@redhat.com> |
kswapd should only wait on IO if there is IO The current kswapd (and try_to_free_pages) code has an oddity where the code will wait on IO, even if there is no IO in flight. This problem is notable especially when the system scans through many unfreeable pages, causing unnecessary stalls in the VM. Additionally, tasks without __GFP_FS or __GFP_IO in the direct reclaim path will sleep if a significant number of pages are encountered that should be written out. This gives kswapd a chance to write out those pages, while the direct reclaim task sleeps. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e1a1cd59 |
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07-Feb-2008 |
Balbir Singh <balbir@linux.vnet.ibm.com> |
Memory controller: make charging gfp mask aware Nick Piggin pointed out that swap cache and page cache addition routines could be called from non GFP_KERNEL contexts. This patch makes the charging routine aware of the gfp context. Charging might fail if the cgroup is over it's limit, in which case a suitable error is returned. This patch was tested on a Powerpc box. I am still looking at being able to test the path, through which allocations happen in non GFP_KERNEL contexts. [kamezawa.hiroyu@jp.fujitsu.com: problem with ZONE_MOVABLE] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Paul Menage <menage@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Kirill Korotaev <dev@sw.ru> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: David Rientjes <rientjes@google.com> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bed7161a |
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07-Feb-2008 |
Balbir Singh <balbir@linux.vnet.ibm.com> |
Memory controller: make page_referenced() cgroup aware Make page_referenced() cgroup aware. Without this patch, page_referenced() can cause a page to be skipped while reclaiming pages. This patch ensures that other cgroups do not hold pages in a particular cgroup hostage. It is required to ensure that shared pages are freed from a cgroup when they are not actively referenced from the cgroup that brought them in Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Paul Menage <menage@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Kirill Korotaev <dev@sw.ru> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: David Rientjes <rientjes@google.com> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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66e1707b |
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07-Feb-2008 |
Balbir Singh <balbir@linux.vnet.ibm.com> |
Memory controller: add per cgroup LRU and reclaim Add the page_cgroup to the per cgroup LRU. The reclaim algorithm has been modified to make the isolate_lru_pages() as a pluggable component. The scan_control data structure now accepts the cgroup on behalf of which reclaims are carried out. try_to_free_pages() has been extended to become cgroup aware. [akpm@linux-foundation.org: fix warning] [Lee.Schermerhorn@hp.com: initialize all scan_control's isolate_pages member] [bunk@kernel.org: make do_try_to_free_pages() static] [hugh@veritas.com: memcgroup: fix try_to_free order] [kamezawa.hiroyu@jp.fujitsu.com: this unlock_page_cgroup() is unnecessary] Signed-off-by: Pavel Emelianov <xemul@openvz.org> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Kirill Korotaev <dev@sw.ru> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: David Rientjes <rientjes@google.com> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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183ff22b |
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19-Oct-2007 |
Simon Arlott <simon@fire.lp0.eux> |
spelling fixes: mm/ Spelling fixes in mm/. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Signed-off-by: Adrian Bunk <bunk@kernel.org>
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c80544dc |
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18-Oct-2007 |
Stephen Hemminger <shemminger@linux-foundation.org> |
sparse pointer use of zero as null Get rid of sparse related warnings from places that use integer as NULL pointer. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Cc: Andi Kleen <ak@suse.de> Cc: Jeff Garzik <jeff@garzik.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Ian Kent <raven@themaw.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d773ed6b |
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17-Oct-2007 |
David Rientjes <rientjes@google.com> |
mm: test and set zone reclaim lock before starting reclaim Introduces new zone flag interface for testing and setting flags: int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag) Instead of setting and clearing ZONE_RECLAIM_LOCKED each time shrink_zone() is called, this flag is test and set before starting zone reclaim. Zone reclaim starts in __alloc_pages() when a zone's watermark fails and the system is in zone_reclaim_mode. If it's already in reclaim, there's no need to start again so it is simply considered full for that allocation attempt. There is a change of behavior with regard to concurrent zone shrinking. It is now possible for try_to_free_pages() or kswapd to already be shrinking a particular zone when __alloc_pages() starts zone reclaim. In this case, it is possible for two concurrent threads to invoke shrink_zone() for a single zone. This change forbids a zone to be in zone reclaim twice, which was always the behavior, but allows for concurrent try_to_free_pages() or kswapd shrinking when starting zone reclaim. Cc: Andrea Arcangeli <andrea@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e815af95 |
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17-Oct-2007 |
David Rientjes <rientjes@google.com> |
oom: change all_unreclaimable zone member to flags Convert the int all_unreclaimable member of struct zone to unsigned long flags. This can now be used to specify several different zone flags such as all_unreclaimable and reclaim_in_progress, which can now be removed and converted to a per-zone flag. Flags are set and cleared as follows: zone_set_flag(struct zone *zone, zone_flags_t flag) zone_clear_flag(struct zone *zone, zone_flags_t flag) Defines the first zone flags, ZONE_ALL_UNRECLAIMABLE and ZONE_RECLAIM_LOCKED, which have the same semantics as the old zone->all_unreclaimable and zone->reclaim_in_progress, respectively. Also converts all current users that set or clear either flag to use the new interface. Helper functions are defined to test the flags: int zone_is_all_unreclaimable(const struct zone *zone) int zone_is_reclaim_locked(const struct zone *zone) All flag operators are of the atomic variety because there are currently readers that are implemented that do not take zone->lock. [akpm@linux-foundation.org: add needed include] Cc: Andrea Arcangeli <andrea@suse.de> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4106f83a |
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16-Oct-2007 |
Andrea Arcangeli <andrea@suse.de> |
make swappiness safer to use Swappiness isn't a safe sysctl. Setting it to 0 for example can hang a system. That's a corner case but even setting it to 10 or lower can waste enormous amounts of cpu without making much progress. We've customers who wants to use swappiness but they can't because of the current implementation (if you change it so the system stops swapping it really stops swapping and nothing works sane anymore if you really had to swap something to make progress). This patch from Kurt Garloff makes swappiness safer to use (no more huge cpu usage or hangs with low swappiness values). I think the prev_priority can also be nuked since it wastes 4 bytes per zone (that would be an incremental patch but I wait the nr_scan_[in]active to be nuked first for similar reasons). Clearly somebody at some point noticed how broken that thing was and they had to add min(priority, prev_priority) to give it some reliability, but they didn't go the last mile to nuke prev_priority too. Calculating distress only in function of not-racy priority is correct and sure more than enough without having to add randomness into the equation. Patch is tested on older kernels but it compiles and it's quite simple so... Overall I'm not very satisified by the swappiness tweak, since it doesn't rally do anything with the dirty pagecache that may be inactive. We need another kind of tweak that controls the inactive scan and tunes the can_writepage feature (not yet in mainline despite having submitted it a few times), not only the active one. That new tweak will tell the kernel how hard to scan the inactive list for pure clean pagecache (something the mainline kernel isn't capable of yet). We already have that feature working in all our enterprise kernels with the default reasonable tune, or they can't even run a readonly backup with tar without triggering huge write I/O. I think it should be available also in mainline later. Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Kurt Garloff <garloff@suse.de> Signed-off-by: Andrea Arcangeli <andrea@suse.de> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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58c0a4a7 |
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16-Oct-2007 |
Yasunori Goto <y-goto@jp.fujitsu.com> |
Fix panic of cpu online with memory less node When a cpu is onlined on memory-less-node box, kernel panics due to touch NULL pointer of pgdat->kswapd. Current kswapd runs only nodes which have memory. So, calling of set_cpus_allowed() is not necessary for memory-less node. This is fix for it. Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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37c0708d |
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16-Oct-2007 |
Christoph Lameter <clameter@sgi.com> |
Memoryless nodes: Add N_CPU node state We need the check for a node with cpu in zone reclaim. Zone reclaim will not allow remote zone reclaim if a node has a cpu. [Lee.Schermerhorn@hp.com: Move setup of N_CPU node state mask] Signed-off-by: Christoph Lameter <clameter@sgi.com> Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Bob Picco <bob.picco@hp.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@skynet.ie> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9422ffba |
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16-Oct-2007 |
Christoph Lameter <clameter@sgi.com> |
Memoryless nodes: No need for kswapd A node without memory does not need a kswapd. So use the memory map instead of the online map when starting kswapd. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Bob Picco <bob.picco@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@skynet.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
32a4330d |
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16-Oct-2007 |
Rik van Riel <riel@redhat.com> |
mm: prevent kswapd from freeing excessive amounts of lowmem The current VM can get itself into trouble fairly easily on systems with a small ZONE_HIGHMEM, which is common on i686 computers with 1GB of memory. On one side, page_alloc() will allocate down to zone->pages_low, while on the other side, kswapd() and balance_pgdat() will try to free memory from every zone, until every zone has more free pages than zone->pages_high. Highmem can be filled up to zone->pages_low with page tables, ramfs, vmalloc allocations and other unswappable things quite easily and without many bad side effects, since we still have a huge ZONE_NORMAL to do future allocations from. However, as long as the number of free pages in the highmem zone is below zone->pages_high, kswapd will continue swapping things out from ZONE_NORMAL, too! Sami Farin managed to get his system into a stage where kswapd had freed about 700MB of low memory and was still "going strong". The attached patch will make kswapd stop paging out data from zones when there is more than enough memory free. We do go above zone->pages_high in order to keep pressure between zones equal in normal circumstances, but the patch should prevent the kind of excesses that made Sami's computer totally unusable. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c661b078 |
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22-Aug-2007 |
Andy Whitcroft <apw@shadowen.org> |
synchronous lumpy reclaim: wait for page writeback when directly reclaiming contiguous areas Lumpy reclaim works by selecting a lead page from the LRU list and then selecting pages for reclaim from the order-aligned area of pages. In the situation were all pages in that region are inactive and not referenced by any process over time, it works well. In the situation where there is even light load on the system, the pages may not free quickly. Out of a area of 1024 pages, maybe only 950 of them are freed when the allocation attempt occurs because lumpy reclaim returned early. This patch alters the behaviour of direct reclaim for large contiguous blocks. The first attempt to call shrink_page_list() is asynchronous but if it fails, the pages are submitted a second time and the calling process waits for the IO to complete. This may stall allocators waiting for contiguous memory but that should be expected behaviour for high-order users. It is preferable behaviour to potentially queueing unnecessary areas for IO. Note that kswapd will not stall in this fashion. [apw@shadowen.org: update to version 2] [apw@shadowen.org: update to version 3] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e9187bdc |
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22-Aug-2007 |
Andy Whitcroft <apw@shadowen.org> |
synchronous lumpy reclaim: ensure we count pages transitioning inactive via clear_active_flags As pointed out by Mel when reclaim is applied at higher orders a significant amount of IO may be started. As this takes finite time to drain reclaim will consider more areas than ultimatly needed to satisfy the request. This leads to more reclaim than strictly required and reduced success rates. I was able to confirm Mel's test results on systems locally. These show that even under light load the success rates drop off far more than expected. Testing with a modified version of his patch (which follows) I was able to allocate almost all of ZONE_MOVABLE with a near idle system. I ran 5 test passes sequentially following system boot (the system has 29 hugepages in ZONE_MOVABLE): 2.6.23-rc1 11 8 6 7 7 sync_lumpy 28 28 29 29 26 These show that although hugely better than the near 0% success normally expected we can only allocate about a 1/4 of the zone. Using synchronous reclaim for these allocations we get close to 100% as expected. I have also run our standard high order tests and these show no regressions in allocation success rates at rest, and some significant improvements under load. This patch: We are transitioning pages from active to inactive in clear_active_flags, those need counting as PGDEACTIVATE vm events. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
83144186 |
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17-Jul-2007 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
Freezer: make kernel threads nonfreezable by default Currently, the freezer treats all tasks as freezable, except for the kernel threads that explicitly set the PF_NOFREEZE flag for themselves. This approach is problematic, since it requires every kernel thread to either set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't care for the freezing of tasks at all. It seems better to only require the kernel threads that want to or need to be frozen to use some freezer-related code and to remove any freezer-related code from the other (nonfreezable) kernel threads, which is done in this patch. The patch causes all kernel threads to be nonfreezable by default (ie. to have PF_NOFREEZE set by default) and introduces the set_freezable() function that should be called by the freezable kernel threads in order to unset PF_NOFREEZE. It also makes all of the currently freezable kernel threads call set_freezable(), so it shouldn't cause any (intentional) change of behaviour to appear. Additionally, it updates documentation to describe the freezing of tasks more accurately. [akpm@linux-foundation.org: build fixes] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8e1f936b |
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17-Jul-2007 |
Rusty Russell <rusty@rustcorp.com.au> |
mm: clean up and kernelify shrinker registration I can never remember what the function to register to receive VM pressure is called. I have to trace down from __alloc_pages() to find it. It's called "set_shrinker()", and it needs Your Help. 1) Don't hide struct shrinker. It contains no magic. 2) Don't allocate "struct shrinker". It's not helpful. 3) Call them "register_shrinker" and "unregister_shrinker". 4) Call the function "shrink" not "shrinker". 5) Reduce the 17 lines of waffly comments to 13, but document it properly. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: David Chinner <dgc@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
5ad333eb |
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17-Jul-2007 |
Andy Whitcroft <apw@shadowen.org> |
Lumpy Reclaim V4 When we are out of memory of a suitable size we enter reclaim. The current reclaim algorithm targets pages in LRU order, which is great for fairness at order-0 but highly unsuitable if you desire pages at higher orders. To get pages of higher order we must shoot down a very high proportion of memory; >95% in a lot of cases. This patch set adds a lumpy reclaim algorithm to the allocator. It targets groups of pages at the specified order anchored at the end of the active and inactive lists. This encourages groups of pages at the requested orders to move from active to inactive, and active to free lists. This behaviour is only triggered out of direct reclaim when higher order pages have been requested. This patch set is particularly effective when utilised with an anti-fragmentation scheme which groups pages of similar reclaimability together. This patch set is based on Peter Zijlstra's lumpy reclaim V2 patch which forms the foundation. Credit to Mel Gorman for sanitity checking. Mel said: The patches have an application with hugepage pool resizing. When lumpy-reclaim is used used with ZONE_MOVABLE, the hugepages pool can be resized with greater reliability. Testing on a desktop machine with 2GB of RAM showed that growing the hugepage pool with ZONE_MOVABLE on it's own was very slow as the success rate was quite low. Without lumpy-reclaim, each attempt to grow the pool by 100 pages would yield 1 or 2 hugepages. With lumpy-reclaim, getting 40 to 70 hugepages on each attempt was typical. [akpm@osdl.org: ia64 pfn_to_nid fixes and loop cleanup] [bunk@stusta.de: static declarations for internal functions] [a.p.zijlstra@chello.nl: initial lumpy V2 implementation] Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Bob Picco <bob.picco@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8bb78442 |
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09-May-2007 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
Add suspend-related notifications for CPU hotplug Since nonboot CPUs are now disabled after tasks and devices have been frozen and the CPU hotplug infrastructure is used for this purpose, we need special CPU hotplug notifications that will help the CPU-hotplug-aware subsystems distinguish normal CPU hotplug events from CPU hotplug events related to a system-wide suspend or resume operation in progress. This patch introduces such notifications and causes them to be used during suspend and resume transitions. It also changes all of the CPU-hotplug-aware subsystems to take these notifications into consideration (for now they are handled in the same way as the corresponding "normal" ones). [oleg@tv-sign.ru: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3e9f45bd |
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08-May-2007 |
Guillaume Chazarain <guichaz@yahoo.fr> |
Factor outstanding I/O error handling Cleanup: setting an outstanding error on a mapping was open coded too many times. Factor it out in mapping_set_error(). Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
b1296cc4 |
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06-May-2007 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
freezer: fix racy usage of try_to_freeze in kswapd Currently we can miss freeze_process()->signal_wake_up() in kswapd() if it happens between try_to_freeze() and prepare_to_wait(). To prevent this from happening we should check freezing(current) before calling schedule(). Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
232ea4d6 |
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28-Feb-2007 |
Andrew Morton <akpm@linux-foundation.org> |
[PATCH] throttle_vm_writeout(): don't loop on GFP_NOFS and GFP_NOIO allocations throttle_vm_writeout() is designed to wait for the dirty levels to subside. But if the caller holds IO or FS locks, we might be holding up that writeout. So change it to take a single nap to give other devices a chance to clean some memory, then return. Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Kumar Gala <galak@kernel.crashing.org> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c8785385 |
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10-Feb-2007 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Use ZVC for inactive and active counts The determination of the dirty ratio to determine writeback behavior is currently based on the number of total pages on the system. However, not all pages in the system may be dirtied. Thus the ratio is always too low and can never reach 100%. The ratio may be particularly skewed if large hugepage allocations, slab allocations or device driver buffers make large sections of memory not available anymore. In that case we may get into a situation in which f.e. the background writeback ratio of 40% cannot be reached anymore which leads to undesired writeback behavior. This patchset fixes that issue by determining the ratio based on the actual pages that may potentially be dirty. These are the pages on the active and the inactive list plus free pages. The problem with those counts has so far been that it is expensive to calculate these because counts from multiple nodes and multiple zones will have to be summed up. This patchset makes these counters ZVC counters. This means that a current sum per zone, per node and for the whole system is always available via global variables and not expensive anymore to calculate. The patchset results in some other good side effects: - Removal of the various functions that sum up free, active and inactive page counts - Cleanup of the functions that display information via the proc filesystem. This patch: The use of a ZVC for nr_inactive and nr_active allows a simplification of some counter operations. More ZVC functionality is used for sums etc in the following patches. [akpm@osdl.org: UP build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
76395d37 |
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05-Jan-2007 |
Andrew Morton <akpm@osdl.org> |
[PATCH] shrink_all_memory(): fix lru_pages handling At the end of shrink_all_memory() we forget to recalculate lru_pages: it can be zero. Fix that up, and add a helper function for this operation too. Also, recalculate lru_pages each time around the inner loop to get the balancing correct. Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
918d3f90 |
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29-Dec-2006 |
Shantanu Goel <sgoel01@yahoo.com> |
[PATCH] Buglet in vmscan.c Fix a rather obvious buglet. Noticed while instrumenting the VM using /proc/vmstat. Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
e07aa05b |
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22-Dec-2006 |
Nigel Cunningham <nigel@suspend2.net> |
[PATCH] Fix swapped parameters in mm/vmscan.c The version of mm/vmscan.c in Linus' current tree has swapped parameters in the shrink_all_zones declaration and call, used by the various suspend-to-disk implementations. This doesn't seem to have any great adverse effect, but it's clearly wrong. Signed-off-by: Nigel Cunningham <nigel@suspend2.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
02a0e53d |
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13-Dec-2006 |
Paul Jackson <pj@sgi.com> |
[PATCH] cpuset: rework cpuset_zone_allowed api Elaborate the API for calling cpuset_zone_allowed(), so that users have to explicitly choose between the two variants: cpuset_zone_allowed_hardwall() cpuset_zone_allowed_softwall() Until now, whether or not you got the hardwall flavor depended solely on whether or not you or'd in the __GFP_HARDWALL gfp flag to the gfp_mask argument. If you didn't specify __GFP_HARDWALL, you implicitly got the softwall version. Unfortunately, this meant that users would end up with the softwall version without thinking about it. Since only the softwall version might sleep, this led to bugs with possible sleeping in interrupt context on more than one occassion. The hardwall version requires that the current tasks mems_allowed allows the node of the specified zone (or that you're in interrupt or that __GFP_THISNODE is set or that you're on a one cpuset system.) The softwall version, depending on the gfp_mask, might allow a node if it was allowed in the nearest enclusing cpuset marked mem_exclusive (which requires taking the cpuset lock 'callback_mutex' to evaluate.) This patch removes the cpuset_zone_allowed() call, and forces the caller to explicitly choose between the hardwall and the softwall case. If the caller wants the gfp_mask to determine this choice, they should (1) be sure they can sleep or that __GFP_HARDWALL is set, and (2) invoke the cpuset_zone_allowed_softwall() routine. This adds another 100 or 200 bytes to the kernel text space, due to the few lines of nearly duplicate code at the top of both cpuset_zone_allowed_* routines. It should save a few instructions executed for the calls that turned into calls of cpuset_zone_allowed_hardwall, thanks to not having to set (before the call) then check (within the call) the __GFP_HARDWALL flag. For the most critical call, from get_page_from_freelist(), the same instructions are executed as before -- the old cpuset_zone_allowed() routine it used to call is the same code as the cpuset_zone_allowed_softwall() routine that it calls now. Not a perfect win, but seems worth it, to reduce this chance of hitting a sleeping with irq off complaint again. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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02316067 |
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06-Dec-2006 |
Ingo Molnar <mingo@elte.hu> |
[PATCH] hotplug CPU: clean up hotcpu_notifier() use There was lots of #ifdef noise in the kernel due to hotcpu_notifier(fn, prio) not correctly marking 'fn' as used in the !HOTPLUG_CPU case, and thus generating compiler warnings of unused symbols, hence forcing people to add #ifdefs. the compiler can skip truly unused functions just fine: text data bss dec hex filename 1624412 728710 3674856 6027978 5bfaca vmlinux.before 1624412 728710 3674856 6027978 5bfaca vmlinux.after [akpm@osdl.org: topology.c fix] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
7dfb7103 |
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06-Dec-2006 |
Nigel Cunningham <ncunningham@linuxmail.org> |
[PATCH] Add include/linux/freezer.h and move definitions from sched.h Move process freezing functions from include/linux/sched.h to freezer.h, so that modifications to the freezer or the kernel configuration don't require recompiling just about everything. [akpm@osdl.org: fix ueagle driver] Signed-off-by: Nigel Cunningham <nigel@suspend2.net> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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8357376d |
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06-Dec-2006 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
[PATCH] swsusp: Improve handling of highmem Currently swsusp saves the contents of highmem pages by copying them to the normal zone which is quite inefficient (eg. it requires two normal pages to be used for saving one highmem page). This may be improved by using highmem for saving the contents of saveable highmem pages. Namely, during the suspend phase of the suspend-resume cycle we try to allocate as many free highmem pages as there are saveable highmem pages. If there are not enough highmem image pages to store the contents of all of the saveable highmem pages, some of them will be stored in the "normal" memory. Next, we allocate as many free "normal" pages as needed to store the (remaining) image data. We use a memory bitmap to mark the allocated free pages (ie. highmem as well as "normal" image pages). Now, we use another memory bitmap to mark all of the saveable pages (highmem as well as "normal") and the contents of the saveable pages are copied into the image pages. Then, the second bitmap is used to save the pfns corresponding to the saveable pages and the first one is used to save their data. During the resume phase the pfns of the pages that were saveable during the suspend are loaded from the image and used to mark the "unsafe" page frames. Next, we try to allocate as many free highmem page frames as to load all of the image data that had been in the highmem before the suspend and we allocate so many free "normal" page frames that the total number of allocated free pages (highmem and "normal") is equal to the size of the image. While doing this we have to make sure that there will be some extra free "normal" and "safe" page frames for two lists of PBEs constructed later. Now, the image data are loaded, if possible, into their "original" page frames. The image data that cannot be written into their "original" page frames are loaded into "safe" page frames and their "original" kernel virtual addresses, as well as the addresses of the "safe" pages containing their copies, are stored in one of two lists of PBEs. One list of PBEs is for the copies of "normal" suspend pages (ie. "normal" pages that were saveable during the suspend) and it is used in the same way as previously (ie. by the architecture-dependent parts of swsusp). The other list of PBEs is for the copies of highmem suspend pages. The pages in this list are restored (in a reversible way) right before the arch-dependent code is called. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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e1dbeda6 |
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06-Dec-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] balance_pdgat() cleanup Despaghettify balance_pdgat() a bit. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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bbdb396a |
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28-Oct-2006 |
Martin Bligh <mbligh@google.com> |
[PATCH] Use min of two prio settings in calculating distress for reclaim If try_to_free_pages / balance_pgdat are called with a gfp_mask specifying GFP_IO and/or GFP_FS, they will reclaim the requisite number of pages, and the reset prev_priority to DEF_PRIORITY (or to some other high (ie: unurgent) value). However, another reclaimer without those gfp_mask flags set (say, GFP_NOIO) may still be struggling to reclaim pages. The concurrent overwrite of zone->prev_priority will cause this GFP_NOIO thread to unexpectedly cease deactivating mapped pages, thus causing reclaim difficulties. Fix this is to key the distress calculation not off zone->prev_priority, but also take into account the local caller's priority by using min(zone->prev_priority, sc->priority) Signed-off-by: Martin J. Bligh <mbligh@google.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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3bb1a852 |
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28-Oct-2006 |
Martin Bligh <mbligh@mbligh.org> |
[PATCH] vmscan: Fix temp_priority race The temp_priority field in zone is racy, as we can walk through a reclaim path, and just before we copy it into prev_priority, it can be overwritten (say with DEF_PRIORITY) by another reclaimer. The same bug is contained in both try_to_free_pages and balance_pgdat, but it is fixed slightly differently. In balance_pgdat, we keep a separate priority record per zone in a local array. In try_to_free_pages there is no need to do this, as the priority level is the same for all zones that we reclaim from. Impact of this bug is that temp_priority is copied into prev_priority, and setting this artificially high causes reclaimers to set distress artificially low. They then fail to reclaim mapped pages, when they are, in fact, under severe memory pressure (their priority may be as low as 0). This causes the OOM killer to fire incorrectly. From: Andrew Morton <akpm@osdl.org> __zone_reclaim() isn't modifying zone->prev_priority. But zone->prev_priority is used in the decision whether or not to bring mapped pages onto the inactive list. Hence there's a risk here that __zone_reclaim() will fail because zone->prev_priority ir large (ie: low urgency) and lots of mapped pages end up stuck on the active list. Fix that up by decreasing (ie making more urgent) zone->prev_priority as __zone_reclaim() scans the zone's pages. This bug perhaps explains why ZONE_RECLAIM_PRIORITY was created. It should be possible to remove that now, and to just start out at DEF_PRIORITY? Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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3fcfab16 |
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20-Oct-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] separate bdi congestion functions from queue congestion functions Separate out the concept of "queue congestion" from "backing-dev congestion". Congestion is a backing-dev concept, not a queue concept. The blk_* congestion functions are retained, as wrappers around the core backing-dev congestion functions. This proper layering is needed so that NFS can cleanly use the congestion functions, and so that CONFIG_BLOCK=n actually links. Cc: "Thomas Maier" <balagi@justmail.de> Cc: "Jens Axboe" <jens.axboe@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Howells <dhowells@redhat.com> Cc: Peter Osterlund <petero2@telia.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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a649fd92 |
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17-Oct-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] invalidate: remove_mapping() fix If remove_mapping() failed to remove the page from its mapping, don't go and mark it not uptodate! Makes kernel go dead. (Actually, I don't think the ClearPageUptodate is needed there at all). Says Nick Piggin: "Right, it isn't needed because at this point the page is guaranteed by remove_mapping to have no references (except us) and cannot pick up any new ones because it is removed from pagecache. We can delete it." Signed-off-by: Andrew Morton <akpm@osdl.org> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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0fd0e6b0 |
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27-Sep-2006 |
Nick Piggin <nickpiggin@yahoo.com.au> |
[PATCH] page invalidation cleanup Clean up the invalidate code, and use a common function to safely remove the page from pagecache. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
e129b5c2 |
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27-Sep-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] vm: add per-zone writeout counter The VM is supposed to minimise the number of pages which get written off the LRU (for IO scheduling efficiency, and for high reclaim-success rates). But we don't actually have a clear way of showing how true this is. So add `nr_vmscan_write' to /proc/vmstat and /proc/zoneinfo - the number of pages which have been written by the vm scanner in this zone and globally. Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
89fa3024 |
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26-Sep-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] NUMA: Add zone_to_nid function There are many places where we need to determine the node of a zone. Currently we use a difficult to read sequence of pointer dereferencing. Put that into an inline function and use throughout VM. Maybe we can find a way to optimize the lookup in the future. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
83e33a47 |
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26-Sep-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zone reclaim with slab: avoid unecessary off node allocations Minor performance fix. If we reclaimed enough slab pages from a zone then we can avoid going off node with the current allocation. Take care of updating nr_reclaimed when reclaiming from the slab. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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0ff38490 |
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26-Sep-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zone_reclaim: dynamic slab reclaim Currently one can enable slab reclaim by setting an explicit option in /proc/sys/vm/zone_reclaim_mode. Slab reclaim is then used as a final option if the freeing of unmapped file backed pages is not enough to free enough pages to allow a local allocation. However, that means that the slab can grow excessively and that most memory of a node may be used by slabs. We have had a case where a machine with 46GB of memory was using 40-42GB for slab. Zone reclaim was effective in dealing with pagecache pages. However, slab reclaim was only done during global reclaim (which is a bit rare on NUMA systems). This patch implements slab reclaim during zone reclaim. Zone reclaim occurs if there is a danger of an off node allocation. At that point we 1. Shrink the per node page cache if the number of pagecache pages is more than min_unmapped_ratio percent of pages in a zone. 2. Shrink the slab cache if the number of the nodes reclaimable slab pages (patch depends on earlier one that implements that counter) are more than min_slab_ratio (a new /proc/sys/vm tunable). The shrinking of the slab cache is a bit problematic since it is not node specific. So we simply calculate what point in the slab we want to reach (current per node slab use minus the number of pages that neeed to be allocated) and then repeately run the global reclaim until that is unsuccessful or we have reached the limit. I hope we will have zone based slab reclaim at some point which will make that easier. The default for the min_slab_ratio is 5% Also remove the slab option from /proc/sys/vm/zone_reclaim_mode. [akpm@osdl.org: cleanups] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
972d1a7b |
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26-Sep-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] ZVC: Support NR_SLAB_RECLAIMABLE / NR_SLAB_UNRECLAIMABLE Remove the atomic counter for slab_reclaim_pages and replace the counter and NR_SLAB with two ZVC counter that account for unreclaimable and reclaimable slab pages: NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE. Change the check in vmscan.c to refer to to NR_SLAB_RECLAIMABLE. The intend seems to be to check for slab pages that could be freed. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
8417bba4 |
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26-Sep-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Replace min_unmapped_ratio by min_unmapped_pages in struct zone *_pages is a better description of the role of the variable. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
4ff1ffb4 |
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26-Sep-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] oom: reclaim_mapped on oom Potentially it takes several scans of the lru lists before we can even start reclaiming pages. mapped pages, with young ptes can take 2 passes on the active list + one on the inactive list. But reclaim_mapped may not always kick in instantly, so it could take even more than that. Raise the threshold for marking a zone as all_unreclaimable from a factor of 4 time the pages in the zone to 6. Introduce a mechanism to force reclaim_mapped if we've reached a factor 3 and still haven't made progress. Previously, a customer doing stress testing was able to easily OOM the box after using only a small fraction of its swap (~100MB). After the patches, it would only OOM after having used up all swap (~800MB). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
408d8544 |
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26-Sep-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] oom: use unreclaimable info __alloc_pages currently starts shooting if page reclaim has failed to free up swap_cluster_max pages in one run through the priorities. This is not always a good indicator on its own, so make use of the all_unreclaimable logic as well: don't consider going OOM until all zones we're interested in are unreclaimable. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
28e4d965 |
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26-Sep-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: remove_mapping() safeness Some users of remove_mapping had been unsafe. Modify the remove_mapping precondition to ensure the caller has locked the page and obtained the correct mapping. Modify callers to ensure the mapping is the correct one. [hugh@veritas.com: swapper_space fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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725d704e |
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26-Sep-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: VM_BUG_ON Introduce a VM_BUG_ON, which is turned on with CONFIG_DEBUG_VM. Use this in the lightweight, inline refcounting functions; PageLRU and PageActive checks in vmscan, because they're pretty well confined to vmscan. And in page allocate/free fastpaths which can be the hottest parts of the kernel for kbuilds. Unlike BUG_ON, VM_BUG_ON must not be used to execute statements with side-effects, and should not be used outside core mm code. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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9614634f |
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03-Jul-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] ZVC/zone_reclaim: Leave 1% of unmapped pagecache pages for file I/O It turns out that it is advantageous to leave a small portion of unmapped file backed pages if all of a zone's pages (or almost all pages) are allocated and so the page allocator has to go off-node. This allows recently used file I/O buffers to stay on the node and reduces the times that zone reclaim is invoked if file I/O occurs when we run out of memory in a zone. The problem is that zone reclaim runs too frequently when the page cache is used for file I/O (read write and therefore unmapped pages!) alone and we have almost all pages of the zone allocated. Zone reclaim may remove 32 unmapped pages. File I/O will use these pages for the next read/write requests and the unmapped pages increase. After the zone has filled up again zone reclaim will remove it again after only 32 pages. This cycle is too inefficient and there are potentially too many zone reclaim cycles. With the 1% boundary we may still remove all unmapped pages for file I/O in zone reclaim pass. However. it will take a large number of read and writes to get back to 1% again where we trigger zone reclaim again. The zone reclaim 2.6.16/17 does not show this behavior because we have a 30 second timeout. [akpm@osdl.org: rename the /proc file and the variable] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
f8891e5e |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Light weight event counters The remaining counters in page_state after the zoned VM counter patches have been applied are all just for show in /proc/vmstat. They have no essential function for the VM. We use a simple increment of per cpu variables. In order to avoid the most severe races we disable preempt. Preempt does not prevent the race between an increment and an interrupt handler incrementing the same statistics counter. However, that race is exceedingly rare, we may only loose one increment or so and there is no requirement (at least not in kernel) that the vm event counters have to be accurate. In the non preempt case this results in a simple increment for each counter. For many architectures this will be reduced by the compiler to a single instruction. This single instruction is atomic for i386 and x86_64. And therefore even the rare race condition in an interrupt is avoided for both architectures in most cases. The patchset also adds an off switch for embedded systems that allows a building of linux kernels without these counters. The implementation of these counters is through inline code that hopefully results in only a single instruction increment instruction being emitted (i386, x86_64) or in the increment being hidden though instruction concurrency (EPIC architectures such as ia64 can get that done). Benefits: - VM event counter operations usually reduce to a single inline instruction on i386 and x86_64. - No interrupt disable, only preempt disable for the preempt case. Preempt disable can also be avoided by moving the counter into a spinlock. - Handling is similar to zoned VM counters. - Simple and easily extendable. - Can be omitted to reduce memory use for embedded use. References: RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2 RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2 local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2 V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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9a865ffa |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: conversion of nr_slab to per zone counter - Allows reclaim to access counter without looping over processor counts. - Allows accurate statistics on how many pages are used in a zone by the slab. This may become useful to balance slab allocations over various zones. [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
34aa1330 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: zone_reclaim: remove /proc/sys/vm/zone_reclaim_interval The zone_reclaim_interval was necessary because we were not able to determine how many unmapped pages exist in a zone. Therefore we had to scan in intervals to figure out if any pages were unmapped. With the zoned counters and NR_ANON_PAGES we now know the number of pagecache pages and the number of mapped pages in a zone. So we can simply skip the reclaim if there is an insufficient number of unmapped pages. We use SWAP_CLUSTER_MAX as the boundary. Drop all support for /proc/sys/vm/zone_reclaim_interval. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
f3dbd344 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: split NR_ANON_PAGES off from NR_FILE_MAPPED The current NR_FILE_MAPPED is used by zone reclaim and the dirty load calculation as the number of mapped pagecache pages. However, that is not true. NR_FILE_MAPPED includes the mapped anonymous pages. This patch separates those and therefore allows an accurate tracking of the anonymous pages per zone. It then becomes possible to determine the number of unmapped pages per zone and we can avoid scanning for unmapped pages if there are none. Also it may now be possible to determine the mapped/unmapped ratio in get_dirty_limit. Isnt the number of anonymous pages irrelevant in that calculation? Note that this will change the meaning of the number of mapped pages reported in /proc/vmstat /proc/meminfo and in the per node statistics. This may affect user space tools that monitor these counters! NR_FILE_MAPPED works like NR_FILE_DIRTY. It is only valid for pagecache pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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bf02cf4b |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: remove NR_FILE_MAPPED from scan control structure We can now access the number of pages in a mapped state in an inexpensive way in shrink_active_list. So drop the nr_mapped field from scan_control. [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
65ba55f5 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: convert nr_mapped to per zone counter nr_mapped is important because it allows a determination of how many pages of a zone are not mapped, which would allow a more efficient means of determining when we need to reclaim memory in a zone. We take the nr_mapped field out of the page state structure and define a new per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off from NR_MAPPED in the next patch). We replace the use of nr_mapped in various kernel locations. This avoids the looping over all processors in try_to_free_pages(), writeback, reclaim (swap + zone reclaim). [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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9c7b216d |
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27-Jun-2006 |
Chandra Seetharaman <sekharan@us.ibm.com> |
[PATCH] cpu hotplug: revert init patch submitted for 2.6.17 In 2.6.17, there was a problem with cpu_notifiers and XFS. I provided a band-aid solution to solve that problem. In the process, i undid all the changes you both were making to ensure that these notifiers were available only at init time (unless CONFIG_HOTPLUG_CPU is defined). We deferred the real fix to 2.6.18. Here is a set of patches that fixes the XFS problem cleanly and makes the cpu notifiers available only at init time (unless CONFIG_HOTPLUG_CPU is defined). If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run time. This patch reverts the notifier_call changes made in 2.6.17 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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3218ae14 |
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27-Jun-2006 |
Yasunori Goto <y-goto@jp.fujitsu.com> |
[PATCH] pgdat allocation for new node add (export kswapd start func) When node is hot-added, kswapd for the node should start. This export kswapd start function as kswapd_run() to use at add_memory(). [akpm@osdl.org: daemonize() isn't needed when using the kthread API] Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: "Brown, Len" <len.brown@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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bd1e22b8 |
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23-Jun-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] initialise total_memory() earlier Initialise total_memory earlier in boot. Because if for some reason we run page reclaim early in boot, we don't want total_memory to be zero when we use it as a divisor. And rename total_memory to vm_total_pages to avoid naming clashes with architectures. Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Martin Bligh <mbligh@google.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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04e62a29 |
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23-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] More page migration: use migration entries for file pages This implements the use of migration entries to preserve ptes of file backed pages during migration. Processes can therefore be migrated back and forth without loosing their connection to pagecache pages. Note that we implement the migration entries only for linear mappings. Nonlinear mappings still require the unmapping of the ptes for migration. And another writepage() ugliness shows up. writepage() can drop the page lock. Therefore we have to remove migration ptes before calling writepages() in order to avoid having migration entries point to unlocked pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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111ebb6e |
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23-Jun-2006 |
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> |
[PATCH] writeback: fix range handling When a writeback_control's `start' and `end' fields are used to indicate a one-byte-range starting at file offset zero, the required values of .start=0,.end=0 mean that the ->writepages() implementation has no way of telling that it is being asked to perform a range request. Because we're currently overloading (start == 0 && end == 0) to mean "this is not a write-a-range request". To make all this sane, the patch changes range of writeback_control. So caller does: If it is calling ->writepages() to write pages, it sets range (range_start/end or range_cyclic) always. And if range_cyclic is true, ->writepages() thinks the range is cyclic, otherwise it just uses range_start and range_end. This patch does, - Add LLONG_MAX, LLONG_MIN, ULLONG_MAX to include/linux/kernel.h -1 is usually ok for range_end (type is long long). But, if someone did, range_end += val; range_end is "val - 1" u64val = range_end >> bits; u64val is "~(0ULL)" or something, they are wrong. So, this adds LLONG_MAX to avoid nasty things, and uses LLONG_MAX for range_end. - All callers of ->writepages() sets range_start/end or range_cyclic. - Fix updates of ->writeback_index. It seems already bit strange. If it starts at 0 and ended by check of nr_to_write, this last index may reduce chance to scan end of file. So, this updates ->writeback_index only if range_cyclic is true or whole-file is scanned. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Nathan Scott <nathans@sgi.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Steven French <sfrench@us.ibm.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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d6277db4 |
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23-Jun-2006 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
[PATCH] swsusp: rework memory shrinker Rework the swsusp's memory shrinker in the following way: - Simplify balance_pgdat() by removing all of the swsusp-related code from it. - Make shrink_all_memory() use shrink_slab() and a new function shrink_all_zones() which calls shrink_active_list() and shrink_inactive_list() directly for each zone in a way that's optimized for suspend. In shrink_all_memory() we try to free exactly as many pages as the caller asks for, preferably in one shot, starting from easier targets. Â If slab caches are huge, they are most likely to have enough pages to reclaim. Â The inactive lists are next (the zones with more inactive pages go first) etc. Each time shrink_all_memory() attempts to shrink the active and inactive lists for each zone in 5 passes. Â In the first pass, only the inactive lists are taken into consideration. Â In the next two passes the active lists are also shrunk, but mapped pages are not reclaimed. Â In the last two passes the active and inactive lists are shrunk and mapped pages are reclaimed as well. The aim of this is to alter the reclaim logic to choose the best pages to keep on resume and improve the responsiveness of the resumed system. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Con Kolivas <kernel@kolivas.org> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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c0bbbc73 |
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11-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] typo in vmscan.c From: Christoph Lameter <clameter@sgi.com> Looks like a comma was left from the conversion from a struct to an assignment. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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83d722f7 |
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24-Apr-2006 |
Chandra Seetharaman <sekharan@us.ibm.com> |
[PATCH] Remove __devinit and __cpuinit from notifier_call definitions Few of the notifier_chain_register() callers use __init in the definition of notifier_call. It is incorrect as the function definition should be available after the initializations (they do not unregister them during initializations). This patch fixes all such usages to _not_ have the notifier_call __init section. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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ec936fc5 |
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27-Mar-2006 |
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
[PATCH] for_each_online_pgdat: renaming for_each_pgdat Replace for_each_pgdat() with for_each_online_pgdat(). Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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05eeae20 |
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25-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] find_task_by_pid() needs tasklist_lock A couple of places are forgetting to take it. The kswapd case is probably unimportant. keventd_create_kthread() was racy. The whole thing is a bit flakey: you start a kernel thread, get its pid from kernel_thread() then look up its task_struct. a) It assumes that pid recycling takes a "long" time. b) We get a task_struct but no reference was taken on it. The owner of the kswapd and kthread task_struct*'s must assume that the new thread won't exit unexpectedly. Because if it does, they're left holding dead memory and any attempt to control or stop that task will crash. Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
b20a3503 |
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22-Mar-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] page migration reorg Centralize the page migration functions in anticipation of additional tinkering. Creates a new file mm/migrate.c 1. Extract buffer_migrate_page() from fs/buffer.c 2. Extract central migration code from vmscan.c 3. Extract some components from mempolicy.c 4. Export pageout() and remove_from_swap() from vmscan.c 5. Make it possible to configure NUMA systems without page migration and non-NUMA systems with page migration. I had to so some #ifdeffing in mempolicy.c that may need a cleanup. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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248a0301 |
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22-Mar-2006 |
Rafael J. Wysocki <rjw@rjwysocki.net> |
[PATCH] mm: make shrink_all_memory try harder Make shrink_all_memory() repeat the attempts to free more memory if there seems to be no pages to free. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
6e5ef1a9 |
|
22-Mar-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] vmscan: emove obsolete checks from shrink_list() and fix unlikely in refill_inactive_zone() As suggested by Marcelo: 1. The optimization introduced recently for not calling page_referenced() during zone reclaim makes two additional checks in shrink_list unnecessary. 2. The if (unlikely(sc->may_swap)) in refill_inactive_zone is optimized for the zone_reclaim case. However, most peoples system only does swap. Undo that. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Marcelo Tosatti <marcelo.tosatti@cyclades.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
0f8053a5 |
|
22-Mar-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: make __put_page internal Remove __put_page from outside the core mm/. It is dangerous because it does not handle compound pages nicely, and misses 1->0 transitions. If a user later appears that really needs the extra speed we can reevaluate. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
fb8d14e1 |
|
22-Mar-2006 |
Wu Fengguang <wfg@mail.ustc.edu.cn> |
[PATCH] mm: shrink_inactive_lis() nr_scan accounting fix In shrink_inactive_list(), nr_scan is not accounted when nr_taken is 0. But 0 pages taken does not mean 0 pages scanned. Move the goto statement below the accounting code to fix it. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
c9b02d97 |
|
22-Mar-2006 |
Wu Fengguang <wfg@mail.ustc.edu.cn> |
[PATCH] mm: isolate_lru_pages() scan count fix In isolate_lru_pages(), *scanned reports one more scan because the scan counter is increased one more time on exit of the while-loop. Change the while-loop to for-loop to fix it. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
7fb2d46d |
|
22-Mar-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone_reclaim: additional comments and cleanup Add some comments to explain how zone reclaim works. And it fixes the following issues: - PF_SWAPWRITE needs to be set for RECLAIM_SWAP to be able to write out pages to swap. Currently RECLAIM_SWAP may not do that. - remove setting nr_reclaimed pages after slab reclaim since the slab shrinking code does not use that and the nr_reclaimed pages is just right for the intended follow up action. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
1742f19f |
|
22-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] vmscan: rename functions We have: try_to_free_pages ->shrink_caches(struct zone **zones, ..) ->shrink_zone(struct zone *, ...) ->shrink_cache(struct zone *, ...) ->shrink_list(struct list_head *, ...) ->refill_inactive_list((struct zone *, ...) which is fairly irrational. Rename things so that we have try_to_free_pages ->shrink_zones(struct zone **zones, ..) ->shrink_zone(struct zone *, ...) ->shrink_inactive_list(struct zone *, ...) ->shrink_page_list(struct list_head *, ...) ->shrink_active_list(struct zone *, ...) Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <christoph@lameter.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
05ff5137 |
|
22-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] vmscan return nr_reclaimed Change all the vmscan functions to retunr the number-of-reclaimed pages and remove scan_conrtol.nr_reclaimed. Saves ten-odd bytes of text and makes things clearer and more consistent. The patch also changes the behaviour of zone_reclaim() when it falls back to slab shrinking. Christoph says "Setting this to one means that we will rescan and shrink the slab for each allocation if we are out of zone memory and RECLAIM_SLAB is set. Plus if we do an order 0 allocation we do not go off node as intended. "We better set this to zero. This means the allocation will go offnode despite us having potentially freed lots of memory on the zone. Future allocations can then again be done from this zone." Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <christoph@lameter.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
69e05944 |
|
22-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] vmscan: use unsigned longs Turn basically everything in vmscan.c into `unsigned long'. This is to avoid the possibility that some piece of code in there might decide to operate upon more than 4G (or even 2G) of pages in one hit. This might be silly, but we'll need it one day. Cc: Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
179e9639 |
|
22-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] vmscan: scan_control cleanup Initialise as much of scan_control as possible at the declaration site. This tidies things up a bit and assures us that all unmentioned fields are zeroed out. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
8695949a |
|
22-Mar-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] Thin out scan_control: remove nr_to_scan and priority Make nr_to_scan and priority a parameter instead of putting it into scan control. This allows various small optimizations and IMHO makes the code easier to read. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
7c8ee9a8 |
|
22-Mar-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: simplify vmscan vs release refcounting The VM has an interesting race where a page refcount can drop to zero, but it is still on the LRU lists for a short time. This was solved by testing a 0->1 refcount transition when picking up pages from the LRU, and dropping the refcount in that case. Instead, use atomic_add_unless to ensure we never pick up a 0 refcount page from the LRU, thus a 0 refcount page will never have its refcount elevated until it is allocated again. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
4c84cacf |
|
22-Mar-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: PageActive no testset PG_active is protected by zone->lru_lock, it does not need TestSet/TestClear operations. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
8d438f96 |
|
22-Mar-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: PageLRU no testset PG_lru is protected by zone->lru_lock. It does not need TestSet/TestClear operations. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
46453a6e |
|
22-Mar-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: never ClearPageLRU released pages If vmscan finds a zero refcount page on the lru list, never ClearPageLRU it. This means the release code need not hold ->lru_lock to stabilise PageLRU, so that lock may be skipped entirely when releasing !PageLRU pages (because we know PageLRU won't have been temporarily cleared by vmscan, which was previously guaranteed by holding the lock to synchronise against vmscan). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
4983da07 |
|
14-Mar-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] page migration: fail if page is in a vma flagged VM_LOCKED page migration currently simply retries a couple of times if try_to_unmap() fails without inspecting the return code. However, SWAP_FAIL indicates that the page is in a vma that has the VM_LOCKED flag set (if ignore_refs ==1). We can check for that return code and avoid retrying the migration. migrate_page_remove_references() now needs to return a reason why the failure occured. So switch migrate_page_remove_references to use -Exx style error messages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
a6bf5270 |
|
09-Mar-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] vmscan: no zone_reclaim if PF_MALLOC is set If the process has already set PF_MALLOC and is already using current->reclaim_state then do not try to reclaim memory from the zone. This is set by kswapd and/or synchrononous global reclaim which will not take it lightly if we zap the reclaim_state. Signed-off-by: Christoph Lameter <clameter@sig.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
d4f7796e |
|
24-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] vmscan: fix zone_reclaim - PF_SWAPWRITE needs to be set for RECLAIM_SWAP to be able to write out pages to swap. Currently RECLAIM_SWAP may not do that. - remove setting nr_reclaimed pages after slab reclaim since the slab shrinking code does not use that and the nr_reclaimed pages is just right for the intended follow up action. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
2903fb16 |
|
11-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] vmscan: skip reclaim_mapped determination if we do not swap This puts the variables and the way to get to reclaim_mapped in one block. And allows zone_reclaim or other things to skip the determination (maybe this whole block of code does not belong into refill_inactive_zone()?) Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
072eaa5d |
|
11-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] vmscan: remove duplicate increment of reclaim_in_progress shrink_zone() already increments reclaim_in_progress. No need to do it in balance_pgdat. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
80e43426 |
|
11-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone reclaim: do not check references to a page during zone reclaim shrink_list() and refill_inactive() check all ptes pointing to a page for reference bits in order to decide if the page should be put on the active list. This is not necessary for zone_reclaim since we are only interested in removing unmapped pages. Skip the checks in both functions. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
418aade4 |
|
10-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] Updates for page migration This adds some additional comments in order to help others figure out how exactly the code works. And fix a variable name. Also swap_page does need to ignore all reference bits when unmapping a page. Otherwise we may have to repeatedly unmap a frequently touched page. So change the try_to_unmap parameter to 1. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
e965f963 |
|
01-Feb-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Direct Migration V9: Avoid writeback / page_migrate() method Migrate a page with buffers without requiring writeback This introduces a new address space operation migratepage() that may be used by a filesystem to implement its own version of page migration. A version is provided that migrates buffers attached to pages. Some filesystems (ext2, ext3, xfs) are modified to utilize this feature. The swapper address space operation are modified so that a regular migrate_page() will occur for anonymous pages without writeback (migrate_pages forces every anonymous page to have a swap entry). Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
a3351e52 |
|
01-Feb-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Direct Migration V9: remove_from_swap() to remove swap ptes Add remove_from_swap remove_from_swap() allows the restoration of the pte entries that existed before page migration occurred for anonymous pages by walking the reverse maps. This reduces swap use and establishes regular pte's without the need for page faults. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
a48d07af |
|
01-Feb-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Direct Migration V9: migrate_pages() extension Add direct migration support with fall back to swap. Direct migration support on top of the swap based page migration facility. This allows the direct migration of anonymous pages and the migration of file backed pages by dropping the associated buffers (requires writeout). Fall back to swap out if necessary. The patch is based on lots of patches from the hotplug project but the code was restructured, documented and simplified as much as possible. Note that an additional patch that defines the migrate_page() method for filesystems is necessary in order to avoid writeback for anonymous and file backed pages. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
2a16e3f4 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] Reclaim slab during zone reclaim If large amounts of zone memory are used by empty slabs then zone_reclaim becomes uneffective. This patch shakes the slab a bit. The problem with this patch is that the slab reclaim is not containable to a zone. Thus slab reclaim may affect the whole system and be extremely slow. This also means that we cannot determine how many pages were freed in this zone. Thus we need to go off node for at least one allocation. The functionality is disabled by default. We could modify the shrinkers to take a zone parameter but that would be quite invasive. Better ideas are welcome. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
1b2ffb78 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] Zone reclaim: Allow modification of zone reclaim behavior In some situations one may want zone_reclaim to behave differently. For example a process writing large amounts of memory will spew unto other nodes to cache the writes if many pages in a zone become dirty. This may impact the performance of processes running on other nodes. Allowing writes during reclaim puts a stop to that behavior and throttles the process by restricting the pages to the local zone. Similarly one may want to contain processes to local memory by enabling regular swap behavior during zone_reclaim. Off node memory allocation can then be controlled through memory policies and cpusets. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
2a11ff06 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone_reclaim: configurable off node allocation period. Currently the zone_reclaim code has a fixed window of 30 seconds of off node allocations should a local zone have no unused pagecache pages left. Reclaim will be attempted again after this timeout period to avoid repeated useless scans for memory. This is also useful to established sufficiently large off node allocation chunks to relieve the local node. It may be beneficial to adjust that time period for some special situations. For example if memory use was exceeding node capacity one may want to give up for longer periods of time. If memory spikes intermittendly then one may want to shorten the time period to reduce the number of off node allocations. This patch allows just that.... Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
a92f7126 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone_reclaim: partial scans instead of full scan Instead of scanning all the pages in a zone, imitate real swap and scan only a portion of the pages and gradually scan more if we do not free up enough pages. This avoids a zone suddenly loosing all unused pagecache pages (we may after all access some of these again so they deserve another chance) but it still frees up large chunks of memory if a zone only contains unused pagecache pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
aa3f18b3 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone_reclaim: do not unmap file backed pages zone_reclaim should leave that to the real swapper. We are only interested in evicting unmapped pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
c84db23c |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone_reclaim: minor fixes - If we only reclaim nr_pages then its okay to stay on node. Switch from > to >= for the comparison. - vm_table[] entry for zone_reclaim_mode is a bit screwed up. - Add empty lines around shrink_zone to show that this is the central function to be called. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
52a8363e |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] mm: improve function of sc->may_writepage Make sc->may_writepage control the writeout behavior of shrink_list. Remove the laptop_mode trick from shrink_list and instead set may_writepage in try_to_free_pages properly. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
42c722d4 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] zone_reclaim: reclaim on memory only node support Zone reclaim is usually only run on the local node. Headless nodes do not have any local processors. This patch checks for headless nodes and performs zone reclaim on them. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
89288623 |
|
01-Feb-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] Optimize off-node performance of zone reclaim Ensure that the performance of off node pages stays the same as before. Off node pagefault tests showed an 18% drop in performance without this patch. - Increase the timeout to 30 seconds to reduce the overhead. - Move all code possible out of the off node hot path for zone reclaim (Sorry Andrew, the struct initialization had to be sacrificed). The read_page_state() bit us there. - Check first for the timeout before any other checks. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
9eeff239 |
|
18-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Zone reclaim: Reclaim logic Some bits for zone reclaim exists in 2.6.15 but they are not usable. This patch fixes them up, removes unused code and makes zone reclaim usable. Zone reclaim allows the reclaiming of pages from a zone if the number of free pages falls below the watermarks even if other zones still have enough pages available. Zone reclaim is of particular importance for NUMA machines. It can be more beneficial to reclaim a page than taking the performance penalties that come with allocating a page on a remote zone. Zone reclaim is enabled if the maximum distance to another node is higher than RECLAIM_DISTANCE, which may be defined by an arch. By default RECLAIM_DISTANCE is 20. 20 is the distance to another node in the same component (enclosure or motherboard) on IA64. The meaning of the NUMA distance information seems to vary by arch. If zone reclaim is not successful then no further reclaim attempts will occur for a certain time period (ZONE_RECLAIM_INTERVAL). This patch was discussed before. See http://marc.theaimsgroup.com/?l=linux-kernel&m=113519961504207&w=2 http://marc.theaimsgroup.com/?l=linux-kernel&m=113408418232531&w=2 http://marc.theaimsgroup.com/?l=linux-kernel&m=113389027420032&w=2 http://marc.theaimsgroup.com/?l=linux-kernel&m=113380938612205&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
f1fd1067 |
|
18-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Zone reclaim: resurrect may_swap Zone reclaim has a huge impact on NUMA performance (f.e. our maximum throughput with XFS is raised from 4GB to 6GB/sec / page cache contamination of numa nodes destroys locality if one just does a large copy operation which results in performance dropping for good until reboot). This patch: Resurrect may_swap in struct scan_control Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
053837fc |
|
18-Jan-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: migration page refcounting fix Migration code currently does not take a reference to target page properly, so between unlocking the pte and trying to take a new reference to the page with isolate_lru_page, anything could happen to it. Fix this by holding the pte lock until we get a chance to elevate the refcount. Other small cleanups while we're here. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
d0d96328 |
|
08-Jan-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] SwapMig: Switch error handling in migrate_pages to use -Exx Use -Exxx instead of numeric return codes and cleanup the code in migrate_pages() using -Exx error codes. Consolidate successful migration handling Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
d4984711 |
|
08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] SwapMig: Extend parameters for migrate_pages() Extend the parameters of migrate_pages() to allow the caller control over the fate of successfully migrated or impossible to migrate pages. Swap migration and direct migration will have the same interface after this patch so that patches can be independently applied to the policy layer and the core migration code. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
#
ee27497d |
|
08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] SwapMig: Drop unused pages immediately Drop unused pages immediately If a page is encountered that is only referenced by the migration code then there is no reason to swap or migrate the page. Release the page by calling move_to_lru(). Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
1480a540 |
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08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] SwapMig: add_to_swap() avoid atomic allocations Add gfp_mask to add_to_swap add_to_swap does allocations with GFP_ATOMIC in order not to interfere with swapping. During migration we may have use add_to_swap extensively which may lead to out of memory errors. This patch makes add_to_swap take a parameter that specifies the gfp mask. The page migration code can then make add_to_swap use GFP_KERNEL. Signed-off-by: Hirokazu Takahashi <taka@valinux.co.jp> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
8419c318 |
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08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] SwapMig: CONFIG_MIGRATION fixes Move move_to_lru, putback_lru_pages and isolate_lru in section surrounded by CONFIG_MIGRATION saving some codesize for single processor kernels. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
7cbe34cf |
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08-Jan-2006 |
Christoph Lameter <clameter@engr.sgi.com> |
[PATCH] Swap Migration V5: Add CONFIG_MIGRATION for page migration support Include page migration if the system is NUMA or having a memory model that allows distinct areas of memory (SPARSEMEM, DISCONTIGMEM). And: - Only include lru_add_drain_per_cpu if building for an SMP system. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
49d2e9cc |
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08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Swap Migration V5: migrate_pages() function This adds the basic page migration function with a minimal implementation that only allows the eviction of pages to swap space. Page eviction and migration may be useful to migrate pages, to suspend programs or for remapping single pages (useful for faulty pages or pages with soft ECC failures) The process is as follows: The function wanting to migrate pages must first build a list of pages to be migrated or evicted and take them off the lru lists via isolate_lru_page(). isolate_lru_page determines that a page is freeable based on the LRU bit set. Then the actual migration or swapout can happen by calling migrate_pages(). migrate_pages does its best to migrate or swapout the pages and does multiple passes over the list. Some pages may only be swappable if they are not dirty. migrate_pages may start writing out dirty pages in the initial passes over the pages. However, migrate_pages may not be able to migrate or evict all pages for a variety of reasons. The remaining pages may be returned to the LRU lists using putback_lru_pages(). Changelog V4->V5: - Use the lru caches to return pages to the LRU Changelog V3->V4: - Restructure code so that applying patches to support full migration does require minimal changes. Rename swapout_pages() to migrate_pages(). Changelog V2->V3: - Extract common code from shrink_list() and swapout_pages() Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: "Michael Kerrisk" <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
930d9152 |
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08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Swap Migration V5: PF_SWAPWRITE to allow writing to swap Add PF_SWAPWRITE to control a processes permission to write to swap. - Use PF_SWAPWRITE in may_write_to_queue() instead of checking for kswapd and pdflush - Set PF_SWAPWRITE flag for kswapd and pdflush Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
21eac81f |
|
08-Jan-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] Swap Migration V5: LRU operations This is the start of the `swap migration' patch series. Swap migration allows the moving of the physical location of pages between nodes in a numa system while the process is running. This means that the virtual addresses that the process sees do not change. However, the system rearranges the physical location of those pages. The main intent of page migration patches here is to reduce the latency of memory access by moving pages near to the processor where the process accessing that memory is running. The patchset allows a process to manually relocate the node on which its pages are located through the MF_MOVE and MF_MOVE_ALL options while setting a new memory policy. The pages of process can also be relocated from another process using the sys_migrate_pages() function call. Requires CAP_SYS_ADMIN. The migrate_pages function call takes two sets of nodes and moves pages of a process that are located on the from nodes to the destination nodes. Manual migration is very useful if for example the scheduler has relocated a process to a processor on a distant node. A batch scheduler or an administrator can detect the situation and move the pages of the process nearer to the new processor. sys_migrate_pages() could be used on non-numa machines as well, to force all of a particualr process's pages out to swap, if someone thinks that's useful. Larger installations usually partition the system using cpusets into sections of nodes. Paul has equipped cpusets with the ability to move pages when a task is moved to another cpuset. This allows automatic control over locality of a process. If a task is moved to a new cpuset then also all its pages are moved with it so that the performance of the process does not sink dramatically (as is the case today). Swap migration works by simply evicting the page. The pages must be faulted back in. The pages are then typically reallocated by the system near the node where the process is executing. For swap migration the destination of the move is controlled by the allocation policy. Cpusets set the allocation policy before calling sys_migrate_pages() in order to move the pages as intended. No allocation policy changes are performed for sys_migrate_pages(). This means that the pages may not faulted in to the specified nodes if no allocation policy was set by other means. The pages will just end up near the node where the fault occurred. There's another patch series in the pipeline which implements "direct migration". The direct migration patchset extends the migration functionality to avoid going through swap. The destination node of the relation is controllable during the actual moving of pages. The crutch of using the allocation policy to relocate is not necessary and the pages are moved directly to the target. Its also faster since swap is not used. And sys_migrate_pages() can then move pages directly to the specified node. Implement functions to isolate pages from the LRU and put them back later. This patch: An earlier implementation was provided by Hirokazu Takahashi <taka@valinux.co.jp> and IWAMOTO Toshihiro <iwamoto@valinux.co.jp> for the memory hotplug project. From: Magnus This breaks out isolate_lru_page() and putpack_lru_page(). Needed for swap migration. Signed-off-by: Magnus Damm <magnus.damm@gmail.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
9d0243bc |
|
08-Jan-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] drop-pagecache Add /proc/sys/vm/drop_caches. When written to, this will cause the kernel to discard as much pagecache and/or reclaimable slab objects as it can. THis operation requires root permissions. It won't drop dirty data, so the user should run `sync' first. Caveats: a) Holds inode_lock for exorbitant amounts of time. b) Needs to be taught about NUMA nodes: propagate these all the way through so the discarding can be controlled on a per-node basis. This is a debugging feature: useful for getting consistent results between filesystem benchmarks. We could possibly put it under a config option, but it's less than 300 bytes. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
a74609fa |
|
06-Jan-2006 |
Nick Piggin <nickpiggin@yahoo.com.au> |
[PATCH] mm: page_state opt Optimise page_state manipulations by introducing interrupt unsafe accessors to page_state fields. Callers must provide their own locking (either disable interrupts or not update from interrupt context). Switch over the hot callsites that can easily be moved under interrupts off sections. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
f3fe6512 |
|
06-Jan-2006 |
Con Kolivas <kernel@kolivas.org> |
[PATCH] mm: add populated_zone() helper There are numerous places we check whether a zone is populated or not. Provide a helper function to check for populated zones and convert all checks for zone->present_pages. Signed-off-by: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
210fe530 |
|
06-Jan-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] vmscan: balancing fix Revert a patch which went into 2.6.8-rc1. The changelog for that patch was: The shrink_zone() logic can, under some circumstances, cause far too many pages to be reclaimed. Say, we're scanning at high priority and suddenly hit a large number of reclaimable pages on the LRU. Change things so we bale out when SWAP_CLUSTER_MAX pages have been reclaimed. Problem is, this change caused significant imbalance in inter-zone scan balancing by truncating scans of larger zones. Suppose, for example, ZONE_HIGHMEM is 10x the size of ZONE_NORMAL. The zone balancing algorithm would require that if we're scanning 100 pages of ZONE_HIGHMEM, we should scan 10 pages of ZONE_NORMAL. But this logic will cause the scanning of ZONE_HIGHMEM to bale out after only 32 pages are reclaimed. Thus effectively causing smaller zones to be scanned relatively harder than large ones. Now I need to remember what the workload was which caused me to write this patch originally, then fix it up in a different way... Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
7756b9e4 |
|
06-Jan-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] kill last zone_reclaim() bits Remove the last bits of Martin's ill-fated sys_set_zone_reclaim(). Cc: Martin Hicks <mort@wildopensource.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
994fc28c |
|
15-Dec-2005 |
Zach Brown <zach.brown@oracle.com> |
[PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE readpage(), prepare_write(), and commit_write() callers are updated to understand the special return code AOP_TRUNCATED_PAGE in the style of writepage() and WRITEPAGE_ACTIVATE. AOP_TRUNCATED_PAGE tells the caller that the callee has unlocked the page and that the operation should be tried again with a new page. OCFS2 uses this to detect and work around a lock inversion in its aop methods. There should be no change in behaviour for methods that don't return AOP_TRUNCATED_PAGE. WRITEPAGE_ACTIVATE is also prepended with AOP_ for consistency and they are made enums so that kerneldoc can be used to document their semantics. Signed-off-by: Zach Brown <zach.brown@oracle.com>
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#
ea164d73 |
|
28-Nov-2005 |
Andrea Arcangeli <andrea@suse.de> |
[PATCH] shrinker->nr = LONG_MAX means deadlock for icache With Andrew Morton <akpm@osdl.org> The slab scanning code tries to balance the scanning rate of slabs versus the scanning rate of LRU pages. To do this, it retains state concerning how many slabs have been scanned - if a particular slab shrinker didn't scan enough objects, we remember that for next time, and scan more objects on the next pass. The problem with this is that with (say) a huge number of GFP_NOIO direct-reclaim attempts, the number of objects which are to be scanned when we finally get a GFP_KERNEL request can be huge. Because some shrinker handlers just bail out if !__GFP_FS. So the patch clamps the number of objects-to-be-scanned to 2* the total number of objects in the slab cache. Signed-off-by: Andrea Arcangeli <andrea@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
f7b7fd8f |
|
28-Nov-2005 |
Rik van Riel <riel@redhat.com> |
[PATCH] temporarily disable swap token on memory pressure Some users (hi Zwane) have seen a problem when running a workload that eats nearly all of physical memory - th system does an OOM kill, even when there is still a lot of swap free. The problem appears to be a very big task that is holding the swap token, and the VM has a very hard time finding any other page in the system that is swappable. Instead of ignoring the swap token when sc->priority reaches 0, we could simply take the swap token away from the memory hog and make sure we don't give it back to the memory hog for a few seconds. This patch resolves the problem Zwane ran into. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
7fb1d9fc |
|
13-Nov-2005 |
Rohit Seth <rohit.seth@intel.com> |
[PATCH] mm: __alloc_pages cleanup Clean up of __alloc_pages. Restoration of previous behaviour, plus further cleanups by introducing an 'alloc_flags', removing the last of should_reclaim_zone. Signed-off-by: Rohit Seth <rohit.seth@intel.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
4c21e2f2 |
|
29-Oct-2005 |
Hugh Dickins <hugh@veritas.com> |
[PATCH] mm: split page table lock Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
c340010e |
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29-Oct-2005 |
Lee Schermerhorn <lee.schermerhorn@hp.com> |
[PATCH] shrink_list(): skip anon pages if not may_swap Martin Hicks' page cache reclaim patch added the 'may_swap' flag to the scan_control struct; and modified shrink_list() not to add anon pages to the swap cache if may_swap is not asserted. Ref: http://marc.theaimsgroup.com/?l=linux-mm&m=111461480725322&w=4 However, further down, if the page is mapped, shrink_list() calls try_to_unmap() which will call try_to_unmap_one() via try_to_unmap_anon (). try_to_unmap_one() will BUG_ON() an anon page that is NOT in the swap cache. Martin says he never encountered this path in his testing, but agrees that it might happen. This patch modifies shrink_list() to skip anon pages that are not already in the swap cache when !may_swap, rather than just not adding them to the cache. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
6daa0e28 |
|
21-Oct-2005 |
Al Viro <viro@zeniv.linux.org.uk> |
[PATCH] gfp_t: mm/* (easy parts) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
3d80636a |
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16-Oct-2005 |
Linus Torvalds <torvalds@g5.osdl.org> |
Fix memory ordering bug in page reclaim As noticed by Nick Piggin, we need to make sure that we check the page count before we check for PageDirty, since the dirty check is only valid if the count implies that we're the only possible ones holding the page. We always did do this, but the code needs a read-memory-barrier to make sure that the orderign is also honored by the CPU. (The writer side is ordered due to the atomic decrement and test on the page count, see the discussion on linux-kernel) Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
8d0986e2 |
|
13-Sep-2005 |
Con Kolivas <kernel@kolivas.org> |
[PATCH] vm: kswapd cleanup: use pgdat Use the pgdat pointer we've already defined in wakeup_kswapd Signed-off-by: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
9bf2229f |
|
06-Sep-2005 |
Paul Jackson <pj@sgi.com> |
[PATCH] cpusets: formalize intermediate GFP_KERNEL containment This patch makes use of the previously underutilized cpuset flag 'mem_exclusive' to provide what amounts to another layer of memory placement resolution. With this patch, there are now the following four layers of memory placement available: 1) The whole system (interrupt and GFP_ATOMIC allocations can use this), 2) The nearest enclosing mem_exclusive cpuset (GFP_KERNEL allocations can use), 3) The current tasks cpuset (GFP_USER allocations constrained to here), and 4) Specific node placement, using mbind and set_mempolicy. These nest - each layer is a subset (same or within) of the previous. Layer (2) above is new, with this patch. The call used to check whether a zone (its node, actually) is in a cpuset (in its mems_allowed, actually) is extended to take a gfp_mask argument, and its logic is extended, in the case that __GFP_HARDWALL is not set in the flag bits, to look up the cpuset hierarchy for the nearest enclosing mem_exclusive cpuset, to determine if placement is allowed. The definition of GFP_USER, which used to be identical to GFP_KERNEL, is changed to also set the __GFP_HARDWALL bit, in the previous cpuset_gfp_hardwall_flag patch. GFP_ATOMIC and GFP_KERNEL allocations will stay within the current tasks cpuset, so long as any node therein is not too tight on memory, but will escape to the larger layer, if need be. The intended use is to allow something like a batch manager to handle several jobs, each job in its own cpuset, but using common kernel memory for caches and such. Swapper and oom_kill activity is also constrained to Layer (2). A task in or below one mem_exclusive cpuset should not cause swapping on nodes in another non-overlapping mem_exclusive cpuset, nor provoke oom_killing of a task in another such cpuset. Heavy use of kernel memory for i/o caching and such by one job should not impact the memory available to jobs in other non-overlapping mem_exclusive cpusets. This patch enables providing hardwall, inescapable cpusets for memory allocations of each job, while sharing kernel memory allocations between several jobs, in an enclosing mem_exclusive cpuset. Like Dinakar's patch earlier to enable administering sched domains using the cpu_exclusive flag, this patch also provides a useful meaning to a cpuset flag that had previously done nothing much useful other than restrict what cpuset configurations were allowed. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
53e9a615 |
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03-Sep-2005 |
Martin Hicks <mort@bork.org> |
[PATCH] VM: zone reclaim atomic ops cleanup Christoph Lameter and Marcelo Tosatti asked to get rid of the atomic_inc_and_test() to cleanup the atomic ops in the zone reclaim code. Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
bce5f6ba |
|
03-Sep-2005 |
Martin Hicks <mort@sgi.com> |
[PATCH] VM: add capabilites check to set_zone_reclaim Add a capability check to sys_set_zone_reclaim(). This syscall is not something that should be available to a user. Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
687a21ce |
|
28-Jun-2005 |
Pekka J Enberg <penberg@cs.Helsinki.FI> |
[PATCH] rename wakeup_bdflush to wakeup_pdflush Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
3e1d1d28 |
|
25-Jun-2005 |
Christoph Lameter <christoph@lameter.com> |
[PATCH] Cleanup patch for process freezing 1. Establish a simple API for process freezing defined in linux/include/sched.h: frozen(process) Check for frozen process freezing(process) Check if a process is being frozen freeze(process) Tell a process to freeze (go to refrigerator) thaw_process(process) Restart process frozen_process(process) Process is frozen now 2. Remove all references to PF_FREEZE and PF_FROZEN from all kernel sources except sched.h 3. Fix numerous locations where try_to_freeze is manually done by a driver 4. Remove the argument that is no longer necessary from two function calls. 5. Some whitespace cleanup 6. Clear potential race in refrigerator (provides an open window of PF_FREEZE cleared before setting PF_FROZEN, recalc_sigpending does not check PF_FROZEN). This patch does not address the problem of freeze_processes() violating the rule that a task may only modify its own flags by setting PF_FREEZE. This is not clean in an SMP environment. freeze(process) is therefore not SMP safe! Signed-off-by: Christoph Lameter <christoph@lameter.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
1ad539b2 |
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21-Jun-2005 |
Darren Hart <dvhltc@us.ibm.com> |
[PATCH] vm: try_to_free_pages unused argument try_to_free_pages accepts a third argument, order, but hasn't used it since before 2.6.0. The following patch removes the argument and updates all the calls to try_to_free_pages. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
1e7e5a90 |
|
21-Jun-2005 |
Martin Hicks <mort@sgi.com> |
[PATCH] VM: rate limit early reclaim When early zone reclaim is turned on the LRU is scanned more frequently when a zone is low on memory. This limits when the zone reclaim can be called by skipping the scan if another thread (either via kswapd or sync reclaim) is already reclaiming from the zone. Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
753ee728 |
|
21-Jun-2005 |
Martin Hicks <mort@sgi.com> |
[PATCH] VM: early zone reclaim This is the core of the (much simplified) early reclaim. The goal of this patch is to reclaim some easily-freed pages from a zone before falling back onto another zone. One of the major uses of this is NUMA machines. With the default allocator behavior the allocator would look for memory in another zone, which might be off-node, before trying to reclaim from the current zone. This adds a zone tuneable to enable early zone reclaim. It is selected on a per-zone basis and is turned on/off via syscall. Adding some extra throttling on the reclaim was also required (patch 4/4). Without the machine would grind to a crawl when doing a "make -j" kernel build. Even with this patch the System Time is higher on average, but it seems tolerable. Here are some numbers for kernbench runs on a 2-node, 4cpu, 8Gig RAM Altix in the "make -j" run: wall user sys %cpu ctx sw. sleeps ---- ---- --- ---- ------ ------ No patch 1009 1384 847 258 298170 504402 w/patch, no reclaim 880 1376 667 288 254064 396745 w/patch & reclaim 1079 1385 926 252 291625 548873 These numbers are the average of 2 runs of 3 "make -j" runs done right after system boot. Run-to-run variability for "make -j" is huge, so these numbers aren't terribly useful except to seee that with reclaim the benchmark still finishes in a reasonable amount of time. I also looked at the NUMA hit/miss stats for the "make -j" runs and the reclaim doesn't make any difference when the machine is thrashing away. Doing a "make -j8" on a single node that is filled with page cache pages takes 700 seconds with reclaim turned on and 735 seconds without reclaim (due to remote memory accesses). The simple zone_reclaim syscall program is at http://www.bork.org/~mort/sgi/zone_reclaim.c Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
bfbb38fb |
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21-Jun-2005 |
Martin Hicks <mort@sgi.com> |
[PATCH] VM: add may_swap flag to scan_control Here's the next round of these patches. These are totally different in an attempt to meet the "simpler" request after the last patches. For reference the earlier threads are: http://marc.theaimsgroup.com/?l=linux-kernel&m=110839604924587&w=2 http://marc.theaimsgroup.com/?l=linux-mm&m=111461480721249&w=2 This set of patches replaces my other vm- patches that are currently in -mm. So they're against 2.6.12-rc5-mm1 about half way through the -mm patchset. As I said already this patch is a lot simpler. The reclaim is turned on or off on a per-zone basis using a syscall. I haven't tested the x86 syscall, so it might be wrong. It uses the existing reclaim/pageout code with the small addition of a may_swap flag to scan_control (patch 1/4). I also added __GFP_NORECLAIM (patch 3/4) so that certain allocation types can be flagged to never cause reclaim. This was a deficiency that was in all of my earlier patch sets. Previously, doing a big buffered read would fill one zone with page cache and then start to reclaim from that same zone, leaving the other zones untouched. Adding some extra throttling on the reclaim was also required (patch 4/4). Without the machine would grind to a crawl when doing a "make -j" kernel build. Even with this patch the System Time is higher on average, but it seems tolerable. Here are some numbers for kernbench runs on a 2-node, 4cpu, 8Gig RAM Altix in the "make -j" run: wall user sys %cpu ctx sw. sleeps ---- ---- --- ---- ------ ------ No patch 1009 1384 847 258 298170 504402 w/patch, no reclaim 880 1376 667 288 254064 396745 w/patch & reclaim 1079 1385 926 252 291625 548873 These numbers are the average of 2 runs of 3 "make -j" runs done right after system boot. Run-to-run variability for "make -j" is huge, so these numbers aren't terribly useful except to seee that with reclaim the benchmark still finishes in a reasonable amount of time. I also looked at the NUMA hit/miss stats for the "make -j" runs and the reclaim doesn't make any difference when the machine is thrashing away. Doing a "make -j8" on a single node that is filled with page cache pages takes 700 seconds with reclaim turned on and 735 seconds without reclaim (due to remote memory accesses). The simple zone_reclaim syscall program is at http://www.bork.org/~mort/sgi/zone_reclaim.c This patch: This adds an extra switch to the scan_control struct. It simply lets the reclaim code know if its allowed to swap pages out. This was required for a simple per-zone reclaimer. Without this addition pages would be swapped out as soon as a zone ran out of memory and the early reclaim kicked in. Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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b15e0905 |
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21-Jun-2005 |
akpm@osdl.org <akpm@osdl.org> |
[PATCH] vmscan: notice slab shrinking Fix a problem identified by Andrea Arcangeli <andrea@suse.de> kswapd will set a zone into all_unreclaimable state if it sees that we're not successfully reclaiming LRU pages. But that fails to notice that we're successfully reclaiming slab obects, so we can set all_unreclaimable too soon. So change shrink_slab() to return a success indication if it actually reclaimed some objects, and don't assume that the zone is all_unreclaimable if that is true. This means that we won't enter all_unreclaimable state if we are successfully freeing slab objects but we're not yet actually freeing slab pages, due to internal fragmentation. (hm, this has a shortcoming. We could be successfully freeing ZONE_NORMAL slab objects while being really oom on ZONE_DMA. If that happens then kswapd might burn a lot of CPU. But given that there might be some slab objects in ZONE_DMA, perhaps that is appropriate.) Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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323aca6c |
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16-Apr-2005 |
akpm@osdl.org <akpm@osdl.org> |
[PATCH] vmscan: pageout(): remove unneeded test We only call pageout() for dirty pages, so this test is redundant. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1da177e4 |
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16-Apr-2005 |
Linus Torvalds <torvalds@ppc970.osdl.org> |
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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