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120b1162 |
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28-Oct-2022 |
Liam Howlett <liam.howlett@oracle.com> |
maple_tree: reorganize testing to restore module testing Along the development cycle, the testing code support for module/in-kernel compiles was removed. Restore this functionality by moving any internal API tests to the userspace side, as well as threading tests. Fix the lockdep issues and add a way to reduce memory usage so the tests can complete with KASAN + memleak detection. Make the tests work on 32 bit hosts where possible and detect 32 bit hosts in the radix test suite. [akpm@linux-foundation.org: fix module export] [akpm@linux-foundation.org: fix it some more] [liam.howlett@oracle.com: fix compile warnings on 32bit build in check_find()] Link: https://lkml.kernel.org/r/20221107203816.1260327-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20221028180415.3074673-1-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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54a611b6 |
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06-Sep-2022 |
Liam R. Howlett <Liam.Howlett@Oracle.com> |
Maple Tree: add new data structure Patch series "Introducing the Maple Tree" The maple tree is an RCU-safe range based B-tree designed to use modern processor cache efficiently. There are a number of places in the kernel that a non-overlapping range-based tree would be beneficial, especially one with a simple interface. If you use an rbtree with other data structures to improve performance or an interval tree to track non-overlapping ranges, then this is for you. The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf nodes. With the increased branching factor, it is significantly shorter than the rbtree so it has fewer cache misses. The removal of the linked list between subsequent entries also reduces the cache misses and the need to pull in the previous and next VMA during many tree alterations. The first user that is covered in this patch set is the vm_area_struct, where three data structures are replaced by the maple tree: the augmented rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The long term goal is to reduce or remove the mmap_lock contention. The plan is to get to the point where we use the maple tree in RCU mode. Readers will not block for writers. A single write operation will be allowed at a time. A reader re-walks if stale data is encountered. VMAs would be RCU enabled and this mode would be entered once multiple tasks are using the mm_struct. Davidlor said : Yes I like the maple tree, and at this stage I don't think we can ask for : more from this series wrt the MM - albeit there seems to still be some : folks reporting breakage. Fundamentally I see Liam's work to (re)move : complexity out of the MM (not to say that the actual maple tree is not : complex) by consolidating the three complimentary data structures very : much worth it considering performance does not take a hit. This was very : much a turn off with the range locking approach, which worst case scenario : incurred in prohibitive overhead. Also as Liam and Matthew have : mentioned, RCU opens up a lot of nice performance opportunities, and in : addition academia[1] has shown outstanding scalability of address spaces : with the foundation of replacing the locked rbtree with RCU aware trees. A similar work has been discovered in the academic press https://pdos.csail.mit.edu/papers/rcuvm:asplos12.pdf Sheer coincidence. We designed our tree with the intention of solving the hardest problem first. Upon settling on a b-tree variant and a rough outline, we researched ranged based b-trees and RCU b-trees and did find that article. So it was nice to find reassurances that we were on the right path, but our design choice of using ranges made that paper unusable for us. This patch (of 70): The maple tree is an RCU-safe range based B-tree designed to use modern processor cache efficiently. There are a number of places in the kernel that a non-overlapping range-based tree would be beneficial, especially one with a simple interface. If you use an rbtree with other data structures to improve performance or an interval tree to track non-overlapping ranges, then this is for you. The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf nodes. With the increased branching factor, it is significantly shorter than the rbtree so it has fewer cache misses. The removal of the linked list between subsequent entries also reduces the cache misses and the need to pull in the previous and next VMA during many tree alterations. The first user that is covered in this patch set is the vm_area_struct, where three data structures are replaced by the maple tree: the augmented rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The long term goal is to reduce or remove the mmap_lock contention. The plan is to get to the point where we use the maple tree in RCU mode. Readers will not block for writers. A single write operation will be allowed at a time. A reader re-walks if stale data is encountered. VMAs would be RCU enabled and this mode would be entered once multiple tasks are using the mm_struct. There is additional BUG_ON() calls added within the tree, most of which are in debug code. These will be replaced with a WARN_ON() call in the future. There is also additional BUG_ON() calls within the code which will also be reduced in number at a later date. These exist to catch things such as out-of-range accesses which would crash anyways. Link: https://lkml.kernel.org/r/20220906194824.2110408-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20220906194824.2110408-2-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: David Howells <dhowells@redhat.com> Tested-by: Sven Schnelle <svens@linux.ibm.com> Tested-by: Yu Zhao <yuzhao@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: SeongJae Park <sj@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d198b34f |
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03-Mar-2020 |
Masahiro Yamada <masahiroy@kernel.org> |
.gitignore: add SPDX License Identifier Add SPDX License Identifier to all .gitignore files. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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ad3d6c72 |
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07-Nov-2017 |
Matthew Wilcox <willy@infradead.org> |
xarray: Add XArray load operation The xa_load function brings with it a lot of infrastructure; xa_empty(), xa_is_err(), and large chunks of the XArray advanced API that are used to implement xa_load. As the test-suite demonstrates, it is possible to use the XArray functions on a radix tree. The radix tree functions depend on the GFP flags being stored in the root of the tree, so it's not possible to use the radix tree functions on an XArray. Signed-off-by: Matthew Wilcox <willy@infradead.org>
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c6ce3e2f |
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13-Feb-2017 |
Rehas Sachdeva <aquannie@gmail.com> |
radix tree test suite: Add config option for map shift Add config option "SHIFT=<value>" to Makefile for building test suite with any value of RADIX_TREE_MAP_SHIFT between 3 and 7 inclusive. Signed-off-by: Rehas Sachdeva <aquannie@gmail.com> [mawilcox@microsoft.com: .gitignore, quieten grep, remove on clean] Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
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8ac04868 |
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18-Dec-2016 |
Matthew Wilcox <willy@infradead.org> |
radix tree test suite: Build separate binaries for some tests To allow developers to run a subset of tests, build separate multiorder and idr-test binaries which will run just the tests in those files. Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Rehas Sachdeva <aquannie@gmail.com>
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0a835c4f |
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20-Dec-2016 |
Matthew Wilcox <willy@infradead.org> |
Reimplement IDR and IDA using the radix tree The IDR is very similar to the radix tree. It has some functionality that the radix tree did not have (alloc next free, cyclic allocation, a callback-based for_each, destroy tree), which is readily implementable on top of the radix tree. A few small changes were needed in order to use a tag to represent nodes with free space below them. More extensive changes were needed to support storing NULL as a valid entry in an IDR. Plain radix trees still interpret NULL as a not-present entry. The IDA is reimplemented as a client of the newly enhanced radix tree. As in the current implementation, it uses a bitmap at the last level of the tree. Signed-off-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1366c37e |
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17-Mar-2016 |
Matthew Wilcox <willy@infradead.org> |
radix tree test harness This code is mostly from Andrew Morton and Nick Piggin; tarball downloaded from http://ozlabs.org/~akpm/rtth.tar.gz with sha1sum 0ce679db9ec047296b5d1ff7a1dfaa03a7bef1bd Some small modifications were necessary to the test harness to fix the build with the current Linux source code. I also made minor modifications to automatically test the radix-tree.c and radix-tree.h files that are in the current source tree, as opposed to a copied and slightly modified version. I am sure more could be done to tidy up the harness, as well as adding more tests. [koct9i@gmail.com: fix compilation] Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: 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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