From: Christoph Lameter Subject: SLUB: Avoid referencing kmem_cache struct in slab_alloc. There is the need to use the objects per slab in the first part of __slab_alloc() which is still pretty hot. Copy the number of objects per slab into the kmem_cache_cpu structure. That way we can get the value from a cache line that we already need to touch. This brings the kmem_cache_cpu structure up to 4 even words. There is no increase in the size of kmem_cache_cpu since the size of object is rounded to the next word. Signed-off-by: Christoph Lameter Reviewed-by: Pekka Enberg Signed-off-by: Andrew Morton --- include/linux/slub_def.h | 1 + mm/slub.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) Index: linux-2.6/include/linux/slub_def.h =================================================================== --- linux-2.6.orig/include/linux/slub_def.h 2008-01-07 22:39:36.196031314 -0800 +++ linux-2.6/include/linux/slub_def.h 2008-01-07 22:46:54.289323089 -0800 @@ -17,6 +17,7 @@ struct kmem_cache_cpu { int node; unsigned int offset; unsigned int objsize; + unsigned int objects; }; struct kmem_cache_node { Index: linux-2.6/mm/slub.c =================================================================== --- linux-2.6.orig/mm/slub.c 2008-01-07 22:46:01.585163587 -0800 +++ linux-2.6/mm/slub.c 2008-01-07 22:46:54.289323089 -0800 @@ -1515,7 +1515,7 @@ load_freelist: object = c->page->freelist; c->freelist = object[c->offset]; - c->page->inuse = s->objects; + c->page->inuse = c->objects; c->page->freelist = c->page->end; c->node = page_to_nid(c->page); unlock_out: @@ -1881,6 +1881,7 @@ static void init_kmem_cache_cpu(struct k c->node = 0; c->offset = s->offset / sizeof(void *); c->objsize = s->objsize; + c->objects = s->objects; } static void init_kmem_cache_node(struct kmem_cache_node *n)