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authorNicholas Piggin <npiggin@gmail.com>2021-09-08 05:00:00 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2021-09-08 20:50:27 +0200
commit1e1c15839df084f4011825fee922aa976c9159dc (patch)
treeeba0d3e4771362a9032bb3637607cd41f52b2ae6 /init
parentcheckpatch: improve GIT_COMMIT_ID test (diff)
downloadlinux-1e1c15839df084f4011825fee922aa976c9159dc.tar.xz
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fs/epoll: use a per-cpu counter for user's watches count
This counter tracks the number of watches a user has, to compare against the 'max_user_watches' limit. This causes a scalability bottleneck on SPECjbb2015 on large systems as there is only one user. Changing to a per-cpu counter increases throughput of the benchmark by about 30% on a 16-socket, > 1000 thread system. [rdunlap@infradead.org: fix build errors in kernel/user.c when CONFIG_EPOLL=n] [npiggin@gmail.com: move ifdefs into wrapper functions, slightly improve panic message] Link: https://lkml.kernel.org/r/1628051945.fens3r99ox.astroid@bobo.none [akpm@linux-foundation.org: tweak user_epoll_alloc(), per Guenter] Link: https://lkml.kernel.org/r/20210804191421.GA1900577@roeck-us.net Link: https://lkml.kernel.org/r/20210802032013.2751916-1-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reported-by: Anton Blanchard <anton@ozlabs.org> Cc: Alexander 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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