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| author | Nick Piggin <npiggin@suse.de> | 2009-12-15 16:47:28 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-16 07:20:09 -0800 |
| commit | bf17bb717759d50a2733a7a8157a7c4a25d93abc (patch) | |
| tree | 22468665036b37922664529df976c890c5bed2d0 /drivers/firewire | |
| parent | 7d6feeb287c61aafa88f06345387b1188edf4b86 (diff) | |
| download | lwn-bf17bb717759d50a2733a7a8157a7c4a25d93abc.tar.gz lwn-bf17bb717759d50a2733a7a8157a7c4a25d93abc.zip | |
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 'drivers/firewire')
0 files changed, 0 insertions, 0 deletions