tree 83b54585a883ee062353eb464d93944d08ab4a1c
parent f269f40ad5aeee229ed70044926f44318abe41ef
author Manfred Spraul <manfred@colorfullife.com> 1373324485 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1373391208 -0700

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

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>