Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755682Ab1EIA3M (ORCPT ); Sun, 8 May 2011 20:29:12 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:45584 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752417Ab1EIA3L (ORCPT ); Sun, 8 May 2011 20:29:11 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Andrew Morton Subject: Re: [PATCH] cpumask: alloc_cpumask_var() use NUMA_NO_NODE Cc: kosaki.motohiro@jp.fujitsu.com, LKML , linux-mm@kvack.org In-Reply-To: <20110505124556.3c8a7e5b.akpm@linux-foundation.org> References: <20110428231856.3D54.A69D9226@jp.fujitsu.com> <20110505124556.3c8a7e5b.akpm@linux-foundation.org> Message-Id: <20110509093043.3ABB.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.56.05 [ja] Date: Mon, 9 May 2011 09:29:06 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2310 Lines: 75 Hi > On Thu, 28 Apr 2011 23:17:15 +0900 (JST) > KOSAKI Motohiro wrote: > > > NUMA_NO_NODE and numa_node_id() are different meanings. NUMA_NO_NODE > > is obviously recomended fallback. > > > > Signed-off-by: KOSAKI Motohiro > > --- > > lib/cpumask.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/lib/cpumask.c b/lib/cpumask.c > > index 4f6425d..af3e581 100644 > > --- a/lib/cpumask.c > > +++ b/lib/cpumask.c > > @@ -131,7 +131,7 @@ EXPORT_SYMBOL(zalloc_cpumask_var_node); > > */ > > bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags) > > { > > - return alloc_cpumask_var_node(mask, flags, numa_node_id()); > > + return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE); > > } > > EXPORT_SYMBOL(alloc_cpumask_var); > > > > So effectively this will replace numa_node_id() with numa_mem_id(), > yes? What runtime effects might this have? If I understand correctly, alloc_pages_node(): same effect both NUMA_NO_NODE and numa_node_id() kmalloc_node(): not same effect NUMA_NO_NODE and numa_node_id() because slub.c --------------------------------------------------- slab_alloc() { (snip) if (unlikely(!object || !node_match(c, node))) // slow path else { // fast path and static inline int node_match(struct kmem_cache_cpu *c, int node) { #ifdef CONFIG_NUMA if (node != NUMA_NO_NODE && c->node != node) return 0; #endif return 1; } --------------------------------------------------- In a nutshell, numa_node_id() reduce slab cache reusing chance. Oh, I missed slab.c code. It's using numa_mem_id(). thank you correct me! numa_mem_id() don't have much meanings. It's ia64 HP big machine quirk. it only affect to improve slab performance a little if users try to allocate a memory from a cpu within memoryless node . and, 99% users never use such machine. In a nutshell, NUMA_NO_NODE and numa_node_id() don't have a lot of difference if users are using SLAB. -- 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/