From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx205.postini.com [74.125.245.205]) by kanga.kvack.org (Postfix) with SMTP id 32A926B011A for ; Wed, 9 May 2012 11:10:10 -0400 (EDT) Message-Id: <20120509151008.488635805@linux.com> Date: Wed, 09 May 2012 10:09:53 -0500 From: cl@linux.com From: Christoph Lameter Subject: [Slub cleanup 3/9] slub: Acquire_slab() avoid loop References: <20120509150950.243797150@linux.com> Content-Disposition: inline; filename=simplify Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: linux-mm@kvack.org, David Rientjes Avoid the loop in acquire slab and simply fail if there is a conflict. This will cause the next page on the list to be considered. Acked-by: David Rientjes Signed-off-by: Christoph Lameter --- mm/slub.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) Index: linux-2.6/mm/slub.c =================================================================== --- linux-2.6.orig/mm/slub.c 2012-04-10 10:32:58.634750976 -0500 +++ linux-2.6/mm/slub.c 2012-04-10 10:33:01.818750910 -0500 @@ -1490,12 +1490,12 @@ static inline void remove_partial(struct } /* - * Lock slab, remove from the partial list and put the object into the - * per cpu freelist. + * Remove slab from the partial list, freeze it and + * return the pointer to the freelist. * * Returns a list of objects or NULL if it fails. * - * Must hold list_lock. + * Must hold list_lock since we modify the partial list. */ static inline void *acquire_slab(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page, @@ -1510,22 +1510,24 @@ static inline void *acquire_slab(struct * The old freelist is the list of objects for the * per cpu allocation list. */ - do { - freelist = page->freelist; - counters = page->counters; - new.counters = counters; - if (mode) - new.inuse = page->objects; + freelist = page->freelist; + counters = page->counters; + new.counters = counters; + if (mode) + new.inuse = page->objects; - VM_BUG_ON(new.frozen); - new.frozen = 1; + VM_BUG_ON(new.frozen); + new.frozen = 1; - } while (!__cmpxchg_double_slab(s, page, + if (!__cmpxchg_double_slab(s, page, freelist, counters, NULL, new.counters, - "lock and freeze")); + "acquire_slab")) + + return NULL; remove_partial(n, page); + WARN_ON(!freelist); return freelist; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org