#
f7dc3248 |
|
14-Dec-2023 |
Liang Chen <liangchen.linux@gmail.com> |
skbuff: Optimization of SKB coalescing for page pool In order to address the issues encountered with commit 1effe8ca4e34 ("skbuff: fix coalescing for page_pool fragment recycling"), the combination of the following condition was excluded from skb coalescing: from->pp_recycle = 1 from->cloned = 1 to->pp_recycle = 1 However, with page pool environments, the aforementioned combination can be quite common(ex. NetworkMananger may lead to the additional packet_type being registered, thus the cloning). In scenarios with a higher number of small packets, it can significantly affect the success rate of coalescing. For example, considering packets of 256 bytes size, our comparison of coalescing success rate is as follows: Without page pool: 70% With page pool: 13% Consequently, this has an impact on performance: Without page pool: 2.57 Gbits/sec With page pool: 2.26 Gbits/sec Therefore, it seems worthwhile to optimize this scenario and enable coalescing of this particular combination. To achieve this, we need to ensure the correct increment of the "from" SKB page's page pool reference count (pp_ref_count). Following this optimization, the success rate of coalescing measured in our environment has improved as follows: With page pool: 60% This success rate is approaching the rate achieved without using page pool, and the performance has also been improved: With page pool: 2.52 Gbits/sec Below is the performance comparison for small packets before and after this optimization. We observe no impact to packets larger than 4K. packet size before after improved (bytes) (Gbits/sec) (Gbits/sec) 128 1.19 1.27 7.13% 256 2.26 2.52 11.75% 512 4.13 4.81 16.50% 1024 6.17 6.73 9.05% 2048 14.54 15.47 6.45% 4096 25.44 27.87 9.52% Signed-off-by: Liang Chen <liangchen.linux@gmail.com> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com> Suggested-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
|
#
fcb29877 |
|
12-Dec-2023 |
Randy Dunlap <rdunlap@infradead.org> |
page_pool: fix typos and punctuation Correct spelling (s/and/any) and a run-on sentence. Spell out "multi". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Jesper Dangaard Brouer <hawk@kernel.org> Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Link: https://lore.kernel.org/r/20231213043650.12672-1-rdunlap@infradead.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
0a149ab7 |
|
11-Dec-2023 |
Liang Chen <liangchen.linux@gmail.com> |
page_pool: transition to reference count management after page draining To support multiple users referencing the same fragment, 'pp_frag_count' is renamed to 'pp_ref_count', transitioning pp pages from fragment management to reference count management after draining based on the suggestion from [1]. The idea is that the concept of fragmenting exists before the page is drained, and all related functions retain their current names. However, once the page is drained, its management shifts to being governed by 'pp_ref_count'. Therefore, all functions associated with that lifecycle stage of a pp page are renamed. [1] http://lore.kernel.org/netdev/f71d9448-70c8-8793-dc9a-0eb48a570300@huawei.com Signed-off-by: Liang Chen <liangchen.linux@gmail.com> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Reviewed-by: Mina Almasry <almasrymina@google.com> Link: https://lore.kernel.org/r/20231212044614.42733-2-liangchen.linux@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
d49010ad |
|
26-Nov-2023 |
Jakub Kicinski <kuba@kernel.org> |
net: page_pool: expose page pool stats via netlink Dump the stats into netlink. More clever approaches like dumping the stats per-CPU for each CPU individually to see where the packets get consumed can be implemented in the future. A trimmed example from a real (but recently booted system): $ ./cli.py --no-schema --spec netlink/specs/netdev.yaml \ --dump page-pool-stats-get [{'info': {'id': 19, 'ifindex': 2}, 'alloc-empty': 48, 'alloc-fast': 3024, 'alloc-refill': 0, 'alloc-slow': 48, 'alloc-slow-high-order': 0, 'alloc-waive': 0, 'recycle-cache-full': 0, 'recycle-cached': 0, 'recycle-released-refcnt': 0, 'recycle-ring': 0, 'recycle-ring-full': 0}, {'info': {'id': 18, 'ifindex': 2}, 'alloc-empty': 66, 'alloc-fast': 11811, 'alloc-refill': 35, 'alloc-slow': 66, 'alloc-slow-high-order': 0, 'alloc-waive': 0, 'recycle-cache-full': 1145, 'recycle-cached': 6541, 'recycle-released-refcnt': 0, 'recycle-ring': 1275, 'recycle-ring-full': 0}, {'info': {'id': 17, 'ifindex': 2}, 'alloc-empty': 73, 'alloc-fast': 62099, 'alloc-refill': 413, ... Acked-by: Jesper Dangaard Brouer <hawk@kernel.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
|
#
8ab32fa1 |
|
20-Oct-2023 |
Yunsheng Lin <linyunsheng@huawei.com> |
page_pool: update document about fragment API As more drivers begin to use the fragment API, update the document about how to decide which API to use for the driver author. Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> CC: Lorenzo Bianconi <lorenzo@kernel.org> CC: Alexander Duyck <alexander.duyck@gmail.com> CC: Liang Chen <liangchen.linux@gmail.com> CC: Alexander Lobakin <aleksander.lobakin@intel.com> CC: Dima Tisnek <dimaqq@gmail.com> Link: https://lore.kernel.org/r/20231020095952.11055-5-linyunsheng@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
de97502e |
|
20-Oct-2023 |
Yunsheng Lin <linyunsheng@huawei.com> |
page_pool: introduce page_pool_alloc() API Currently page pool supports the below use cases: use case 1: allocate page without page splitting using page_pool_alloc_pages() API if the driver knows that the memory it need is always bigger than half of the page allocated from page pool. use case 2: allocate page frag with page splitting using page_pool_alloc_frag() API if the driver knows that the memory it need is always smaller than or equal to the half of the page allocated from page pool. There is emerging use case [1] & [2] that is a mix of the above two case: the driver doesn't know the size of memory it need beforehand, so the driver may use something like below to allocate memory with least memory utilization and performance penalty: if (size << 1 > max_size) page = page_pool_alloc_pages(); else page = page_pool_alloc_frag(); To avoid the driver doing something like above, add the page_pool_alloc() API to support the above use case, and update the true size of memory that is acctually allocated by updating '*size' back to the driver in order to avoid exacerbating truesize underestimate problem. Rename page_pool_free() which is used in the destroy process to __page_pool_destroy() to avoid confusion with the newly added API. 1. https://lore.kernel.org/all/d3ae6bd3537fbce379382ac6a42f67e22f27ece2.1683896626.git.lorenzo@kernel.org/ 2. https://lore.kernel.org/all/20230526054621.18371-3-liangchen.linux@gmail.com/ Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> CC: Lorenzo Bianconi <lorenzo@kernel.org> CC: Alexander Duyck <alexander.duyck@gmail.com> CC: Liang Chen <liangchen.linux@gmail.com> CC: Alexander Lobakin <aleksander.lobakin@intel.com> Link: https://lore.kernel.org/r/20231020095952.11055-4-linyunsheng@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
58d53d8f |
|
20-Oct-2023 |
Yunsheng Lin <linyunsheng@huawei.com> |
page_pool: unify frag_count handling in page_pool_is_last_frag() Currently when page_pool_create() is called with PP_FLAG_PAGE_FRAG flag, page_pool_alloc_pages() is only allowed to be called under the below constraints: 1. page_pool_fragment_page() need to be called to setup page->pp_frag_count immediately. 2. page_pool_defrag_page() often need to be called to drain the page->pp_frag_count when there is no more user will be holding on to that page. Those constraints exist in order to support a page to be split into multi fragments. And those constraints have some overhead because of the cache line dirtying/bouncing and atomic update. Those constraints are unavoidable for case when we need a page to be split into more than one fragment, but there is also case that we want to avoid the above constraints and their overhead when a page can't be split as it can only hold a fragment as requested by user, depending on different use cases: use case 1: allocate page without page splitting. use case 2: allocate page with page splitting. use case 3: allocate page with or without page splitting depending on the fragment size. Currently page pool only provide page_pool_alloc_pages() and page_pool_alloc_frag() API to enable the 1 & 2 separately, so we can not use a combination of 1 & 2 to enable 3, it is not possible yet because of the per page_pool flag PP_FLAG_PAGE_FRAG. So in order to allow allocating unsplit page without the overhead of split page while still allow allocating split page we need to remove the per page_pool flag in page_pool_is_last_frag(), as best as I can think of, it seems there are two methods as below: 1. Add per page flag/bit to indicate a page is split or not, which means we might need to update that flag/bit everytime the page is recycled, dirtying the cache line of 'struct page' for use case 1. 2. Unify the page->pp_frag_count handling for both split and unsplit page by assuming all pages in the page pool is split into a big fragment initially. As page pool already supports use case 1 without dirtying the cache line of 'struct page' whenever a page is recyclable, we need to support the above use case 3 with minimal overhead, especially not adding any noticeable overhead for use case 1, and we are already doing an optimization by not updating pp_frag_count in page_pool_defrag_page() for the last fragment user, this patch chooses to unify the pp_frag_count handling to support the above use case 3. There is no noticeable performance degradation and some justification for unifying the frag_count handling with this patch applied using a micro-benchmark testing in [1]. 1. https://lore.kernel.org/all/bf2591f8-7b3c-4480-bb2c-31dc9da1d6ac@huawei.com/ Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> CC: Lorenzo Bianconi <lorenzo@kernel.org> CC: Alexander Duyck <alexander.duyck@gmail.com> CC: Liang Chen <liangchen.linux@gmail.com> CC: Alexander Lobakin <aleksander.lobakin@intel.com> Link: https://lore.kernel.org/r/20231020095952.11055-2-linyunsheng@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
90de47f0 |
|
13-Oct-2023 |
Yunsheng Lin <linyunsheng@huawei.com> |
page_pool: fragment API support for 32-bit arch with 64-bit DMA Currently page_pool_alloc_frag() is not supported in 32-bit arch with 64-bit DMA because of the overlap issue between pp_frag_count and dma_addr_upper in 'struct page' for those arches, which seems to be quite common, see [1], which means driver may need to handle it when using fragment API. It is assumed that the combination of the above arch with an address space >16TB does not exist, as all those arches have 64b equivalent, it seems logical to use the 64b version for a system with a large address space. It is also assumed that dma address is page aligned when we are dma mapping a page aligned buffer, see [2]. That means we're storing 12 bits of 0 at the lower end for a dma address, we can reuse those bits for the above arches to support 32b+12b, which is 16TB of memory. If we make a wrong assumption, a warning is emitted so that user can report to us. 1. https://lore.kernel.org/all/20211117075652.58299-1-linyunsheng@huawei.com/ 2. https://lore.kernel.org/all/20230818145145.4b357c89@kernel.org/ Tested-by: Alexander Lobakin <aleksander.lobakin@intel.com> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> CC: Lorenzo Bianconi <lorenzo@kernel.org> CC: Alexander Duyck <alexander.duyck@gmail.com> CC: Liang Chen <liangchen.linux@gmail.com> CC: Guillaume Tucker <guillaume.tucker@collabora.com> CC: Matthew Wilcox <willy@infradead.org> CC: Linux-MM <linux-mm@kvack.org> Link: https://lore.kernel.org/r/20231013064827.61135-2-linyunsheng@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
513dbc10 |
|
30-Sep-2023 |
Randy Dunlap <rdunlap@infradead.org> |
page_pool: fix documentation typos Correct grammar for better readability. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jesper Dangaard Brouer <hawk@kernel.org> Reviewed-by: Simon Horman <horms@kernel.org> Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Link: https://lore.kernel.org/r/20231001003846.29541-1-rdunlap@infradead.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
2c2b8874 |
|
07-Aug-2023 |
Jakub Kicinski <kuba@kernel.org> |
docs: net: page_pool: de-duplicate the intro comment In commit 82e896d992fa ("docs: net: page_pool: use kdoc to avoid duplicating the information") I shied away from using the DOC: comments when moving to kdoc for documenting page_pool API, because I wasn't sure how familiar people are with it. Turns out there is already a DOC: comment for the intro, which is the same in both places, modulo what looks like minor rewording. Use the version from Documentation/ but keep the contents with the code. Acked-by: Jesper Dangaard Brouer <hawk@kernel.org> Link: https://lore.kernel.org/r/20230807210051.1014580-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
#
a9ca9f9c |
|
04-Aug-2023 |
Yunsheng Lin <linyunsheng@huawei.com> |
page_pool: split types and declarations from page_pool.h Split types and pure function declarations from page_pool.h and add them in page_page/types.h, so that C sources can include page_pool.h and headers should generally only include page_pool/types.h as suggested by jakub. Rename page_pool.h to page_pool/helpers.h to have both in one place. Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> Suggested-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Link: https://lore.kernel.org/r/20230804180529.2483231-2-aleksander.lobakin@intel.com [Jakub: change microsoft/mana, fix kdoc paths in Documentation] Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|