From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 575A16B004A for ; Wed, 20 Jul 2011 11:09:32 -0400 (EDT) Received: by wwj40 with SMTP id 40so283927wwj.26 for ; Wed, 20 Jul 2011 08:09:29 -0700 (PDT) Subject: Re: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT From: Eric Dumazet In-Reply-To: References: <20110720121612.28888.38970.stgit@localhost6> <20110720134342.GK5349@suse.de> <1311170893.2338.29.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Content-Type: text/plain; charset="UTF-8" Date: Wed, 20 Jul 2011 17:09:22 +0200 Message-ID: <1311174562.2338.42.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Mel Gorman , Pekka Enberg , Konstantin Khlebnikov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Matt Mackall Le mercredi 20 juillet 2011 A 09:52 -0500, Christoph Lameter a A(C)crit : > On Wed, 20 Jul 2011, Eric Dumazet wrote: > > > > Slab's kmem_cache is configured with an array of NR_CPUS which is the > > > maximum nr of cpus supported. Some distros support 4096 cpus in order to > > > accomodate SGI machines. That array then will have the size of 4096 * 8 = > > > 32k > > > > We currently support a dynamic schem for the possible nodes : > > > > cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) + > > nr_node_ids * sizeof(struct kmem_list3 *); > > > > We could have a similar trick to make the real size both depends on > > nr_node_ids and nr_cpu_ids. > > > > (struct kmem_cache)->array would become a pointer. > > We should be making it a per cpu pointer like slub then. I looked at what > it would take to do so a couple of month ago but it was quite invasive. > Lets try this first patch, simple enough : No need to setup percpu data for a one time use structure... [PATCH] slab: remove one NR_CPUS dependency Reduce high order allocations in do_tune_cpucache() for some setups. (NR_CPUS=4096 -> we need 64KB) Signed-off-by: Eric Dumazet CC: Pekka Enberg CC: Christoph Lameter --- mm/slab.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index d96e223..862bd12 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3933,7 +3933,7 @@ fail: struct ccupdate_struct { struct kmem_cache *cachep; - struct array_cache *new[NR_CPUS]; + struct array_cache *new[0]; }; static void do_ccupdate_local(void *info) @@ -3955,7 +3955,8 @@ static int do_tune_cpucache(struct kmem_cache *cachep, int limit, struct ccupdate_struct *new; int i; - new = kzalloc(sizeof(*new), gfp); + new = kzalloc(sizeof(*new) + nr_cpu_ids * sizeof(struct array_cache *), + gfp); if (!new) return -ENOMEM; -- 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