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| author | Sebastien Dugue <sebastien.dugue@bull.net> | 2006-06-27 02:55:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-27 17:32:48 -0700 |
| commit | 59e0e0ace7d33e8c0c125042f153f80fcc56b39e (patch) | |
| tree | e73a795bd99b39a886fe3f9b46f85dbf53db5316 /kernel/futex.c | |
| parent | 95e02ca9bb5324360e7dea1ea1c563036d84a5e6 (diff) | |
| download | lwn-59e0e0ace7d33e8c0c125042f153f80fcc56b39e.tar.gz lwn-59e0e0ace7d33e8c0c125042f153f80fcc56b39e.zip | |
[PATCH] futex_requeue() optimization
In futex_requeue(), when the 2 futexes keys hash to the same bucket, there
is no need to move the futex_q to the end of the bucket list.
Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index b305b7f8dad5..6c91f938005d 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -827,17 +827,20 @@ static int futex_requeue(u32 __user *uaddr1, u32 __user *uaddr2, if (++ret <= nr_wake) { wake_futex(this); } else { - list_move_tail(&this->list, &hb2->chain); - this->lock_ptr = &hb2->lock; + /* + * If key1 and key2 hash to the same bucket, no need to + * requeue. + */ + if (likely(head1 != &hb2->chain)) { + list_move_tail(&this->list, &hb2->chain); + this->lock_ptr = &hb2->lock; + } this->key = key2; get_key_refs(&key2); drop_count++; if (ret - nr_wake >= nr_requeue) break; - /* Make sure to stop if key1 == key2: */ - if (head1 == &hb2->chain && head1 != &next->list) - head1 = &this->list; } } |