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authorNick Piggin <npiggin@suse.de>2009-12-15 19:47:28 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-16 10:20:09 -0500
commitbf17bb717759d50a2733a7a8157a7c4a25d93abc (patch)
tree22468665036b37922664529df976c890c5bed2d0 /lib
parent7d6feeb287c61aafa88f06345387b1188edf4b86 (diff)
ipc/sem.c: sem optimise undo list search
Around a month ago, there was some discussion about an improvement of the sysv sem algorithm: Most (at least: some important) users only use simple semaphore operations, therefore it's worthwile to optimize this use case. This patch: Move last looked up sem_undo struct to the head of the task's undo list. Attempt to move common entries to the front of the list so search time is reduced. This reduces lookup_undo on oprofile of problematic SAP workload by 30% (see patch 4 for a description of SAP workload). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> 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 'lib')
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