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authorChristoph Lameter <clameter@sgi.com>2006-03-25 03:06:45 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-25 08:22:49 -0800
commite00946fe2351307eb3eda7a3343530f6d2d1af2e (patch)
tree1567b4abe0ed56fbd960943da2c52278ea196c02
parent3ded175a4b7a4548f3358dcf5f3ad65f63cdb4ed (diff)
[PATCH] slab: Bypass free lists for __drain_alien_cache()
__drain_alien_cache() currently drains objects by freeing them to the (remote) freelists of the original node. However, each node also has a shared list containing objects to be used on any processor of that node. We can avoid a number of remote node accesses by copying the pointers to the free objects directly into the remote shared array. And while we are at it: Skip alien draining if the alien cache spinlock is already taken. Kiran reported that this is a performance benefit. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--mm/slab.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c
index dee857a8680..351aa6c587f 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -971,6 +971,13 @@ static void __drain_alien_cache(struct kmem_cache *cachep,
if (ac->avail) {
spin_lock(&rl3->list_lock);
+ /*
+ * Stuff objects into the remote nodes shared array first.
+ * That way we could avoid the overhead of putting the objects
+ * into the free lists and getting them back later.
+ */
+ transfer_objects(rl3->shared, ac, ac->limit);
+
free_block(cachep, ac->entry, ac->avail, node);
ac->avail = 0;
spin_unlock(&rl3->list_lock);
@@ -986,8 +993,8 @@ static void reap_alien(struct kmem_cache *cachep, struct kmem_list3 *l3)
if (l3->alien) {
struct array_cache *ac = l3->alien[node];
- if (ac && ac->avail) {
- spin_lock_irq(&ac->lock);
+
+ if (ac && ac->avail && spin_trylock_irq(&ac->lock)) {
__drain_alien_cache(cachep, ac, node);
spin_unlock_irq(&ac->lock);
}