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 --- include/linux/slub_def.h | 1 + mm/slub.c | 21 +++++++++++++++++++-- 2 files changed, 20 insertions(+), 2 deletions(-) Index: linux-2.6/mm/slub.c =================================================================== --- linux-2.6.orig/mm/slub.c 2011-05-31 14:27:17.792880073 -0500 +++ linux-2.6/mm/slub.c 2011-05-31 14:27:21.372880046 -0500 @@ -1977,9 +1977,21 @@ static void *__slab_alloc(struct kmem_ca 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_ca 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); @@ -4684,6 +4699,7 @@ STAT_ATTR(DEACTIVATE_EMPTY, deactivate_e 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); @@ -4744,6 +4760,7 @@ 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, Index: linux-2.6/include/linux/slub_def.h =================================================================== --- linux-2.6.orig/include/linux/slub_def.h 2011-05-31 14:27:17.792880073 -0500 +++ linux-2.6/include/linux/slub_def.h 2011-05-31 14:27:21.382880050 -0500 @@ -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 */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/