The patch titled
futex_requeue() optimization
has been added to the -mm tree. Its filename is
futex_requeue-optimization.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
From: Sebastien Dugue <sebastien.dugue@xxxxxxxx>
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@xxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/futex.c | 13 ++++++++-----
1 files changed, 8 insertions(+), 5 deletions(-)
diff -puN kernel/futex.c~futex_requeue-optimization kernel/futex.c
--- devel/kernel/futex.c~futex_requeue-optimization 2006-05-11 09:11:56.000000000 -0700
+++ devel-akpm/kernel/futex.c 2006-05-11 09:11:56.000000000 -0700
@@ -511,17 +511,20 @@ static int futex_requeue(unsigned long u
if (++ret <= nr_wake) {
wake_futex(this);
} else {
- list_move_tail(&this->list, &bh2->chain);
- this->lock_ptr = &bh2->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 == &bh2->chain && head1 != &next->list)
- head1 = &this->list;
}
}
_
Patches currently in -mm which might be from sebastien.dugue@xxxxxxxx are
futex_requeue-optimization.patch
-
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