ipc/sem.c: replace shared sem_otime with per-semaphore value

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sem_otime contains the time of the last semaphore operation that
completed successfully.  Every operation updates this value, thus access
from multiple cpus can cause thrashing.

Therefore the patch replaces the variable with a per-semaphore variable.
The per-array sem_otime is only calculated when required.

No performance improvement on a single-socket i3 - only important for
larger systems.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

...

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Manfred Spraul 2013-07-08 16:01:25 -07:00 • committed by Linus Torvalds

parent f269f40ad5

commit d12e1e50e4

2 changed files with 31 additions and 7 deletions

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include/linux/sem.h

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