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authorJohannes Weiner <hannes@cmpxchg.org>2013-12-19 05:08:47 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-12-19 07:04:51 +0400
commit73f038b863dfe98acabc7c36c17342b84ad52e94 (patch)
tree4cd2132b22b48308bf3676f80fdce1f7691de06b /mm/Kconfig
parentb0943d61b8fa420180f92f64ef67662b4f6cc493 (diff)
downloadlinux-73f038b863dfe98acabc7c36c17342b84ad52e94.tar.xz
mm: page_alloc: exclude unreclaimable allocations from zone fairness policy
Dave Hansen noted a regression in a microbenchmark that loops around open() and close() on an 8-node NUMA machine and bisected it down to commit 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy"). That change forces the slab allocations of the file descriptor to spread out to all 8 nodes, causing remote references in the page allocator and slab. The round-robin policy is only there to provide fairness among memory allocations that are reclaimed involuntarily based on pressure in each zone. It does not make sense to apply it to unreclaimable kernel allocations that are freed manually, in this case instantly after the allocation, and incur the remote reference costs twice for no reason. Only round-robin allocations that are usually freed through page reclaim or slab shrinking. Bisected by Dave Hansen. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@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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