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slub: fast release on full slab

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Make deactivation occur implicitly while checking out the current freelist.

This avoids one cmpxchg operation on a slab that is now fully in use.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Christoph Lameter 2011-06-01 12:25:58 -05:00 committed by Pekka Enberg
parent e36a2652d7
commit 03e404af26
2 changed files with 20 additions and 2 deletions
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1
include/linux/slub_def.h
View File

@ -32,6 +32,7 @@ enum stat_item {
DEACTIVATE_TO_HEAD, /* Cpu slab was moved to the head of partials */
DEACTIVATE_TO_TAIL, /* Cpu slab was moved to the tail of partials */
DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
DEACTIVATE_BYPASS, /* Implicit deactivation */
ORDER_FALLBACK, /* Number of times fallback was necessary */
CMPXCHG_DOUBLE_CPU_FAIL,/* Failure of this_cpu_cmpxchg_double */
CMPXCHG_DOUBLE_FAIL, /* Number of times that cmpxchg double did not match */

21
mm/slub.c
View File

@ -1977,9 +1977,21 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
object = page->freelist;
counters = page->counters;
new.counters = counters;
new.inuse = page->objects;
VM_BUG_ON(!new.frozen);
/*
* If there is no object left then we use this loop to
* deactivate the slab which is simple since no objects
* are left in the slab and therefore we do not need to
* put the page back onto the partial list.
*
* If there are objects left then we retrieve them
* and use them to refill the per cpu queue.
*/
new.inuse = page->objects;
new.frozen = object != NULL;
} while (!cmpxchg_double_slab(s, page,
object, counters,
NULL, new.counters,
@ -1988,8 +2000,11 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
load_freelist:
VM_BUG_ON(!page->frozen);
if (unlikely(!object))
if (unlikely(!object)) {
c->page = NULL;
stat(s, DEACTIVATE_BYPASS);
goto new_slab;
}
stat(s, ALLOC_REFILL);
@ -4680,6 +4695,7 @@ STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
STAT_ATTR(ORDER_FALLBACK, order_fallback);
STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
@ -4740,6 +4756,7 @@ static struct attribute *slab_attrs[] = {
&deactivate_to_head_attr.attr,
&deactivate_to_tail_attr.attr,
&deactivate_remote_frees_attr.attr,
&deactivate_bypass_attr.attr,
&order_fallback_attr.attr,
&cmpxchg_double_fail_attr.attr,
&cmpxchg_double_cpu_fail_attr.attr,