summaryrefslogtreecommitdiff
path: root/.mailmap
diff options
context:
space:
mode:
authorManfred Spraul <manfred@colorfullife.com>2009-12-16 03:47:34 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-16 18:20:10 +0300
commitd987f8b213f2cdcc52b2ca9ee67161516e4d256a (patch)
tree12ed1a267c8fd3ea0343d6a77f1c332b775d4dfe /.mailmap
parent636c6be823870d829b37fc96655bb8820a6a9be9 (diff)
downloadlinux-d987f8b213f2cdcc52b2ca9ee67161516e4d256a.tar.xz
ipc/sem.c: optimize single sops when semval is zero
If multiple simple decrements on the same semaphore are pending, then the current code scans all decrement operations, even if the semaphore value is already 0. The patch optimizes that: if the semaphore value is 0, then there is no need to scan the q->alter entries. Note that this is a common case: It happens if 100 decrements by one are pending and now an increment by one increases the semaphore value from 0 to 1. Without this patch, all 100 entries are scanned. With the patch, only one entry is scanned, then woken up. Then the new rule triggers and the scanning is aborted, without looking at the remaining 99 tasks. With this patch, single sop increment/decrement by 1 are now O(1). (same as with Nick's patch) Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Pierre Peiffer <peifferp@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '.mailmap')
0 files changed, 0 insertions, 0 deletions