Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753761Ab1DSBP3 (ORCPT ); Mon, 18 Apr 2011 21:15:29 -0400 Received: from smtp-out.google.com ([216.239.44.51]:42559 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753357Ab1DSBP1 (ORCPT ); Mon, 18 Apr 2011 21:15:27 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=OXMWGDsgQ75oW3MIDdPqU8zIUJReMhTdFWcCPDJ8erE3eb+75jctrVvrkBCby0muvd kt1ys2nqYr36vm596ZRg== Date: Mon, 18 Apr 2011 18:15:10 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Michal Hocko cc: Andrew Morton , KOSAKI Motohiro , LKML , Jack Steiner , Lee Schermerhorn , Christoph Lameter , Pekka Enberg , Paul Menage , Robin Holt , Linus Torvalds , linux-mm@kvack.org Subject: Re: [PATCH incremental] cpusets: initialize spread rotor lazily In-Reply-To: <20110418212915.GA17376@tiehlicka.suse.cz> Message-ID: References: <20110414065146.GA19685@tiehlicka.suse.cz> <20110414160145.0830.A69D9226@jp.fujitsu.com> <20110415161831.12F8.A69D9226@jp.fujitsu.com> <20110415082051.GB8828@tiehlicka.suse.cz> <20110418084248.GB8925@tiehlicka.suse.cz> <20110418212915.GA17376@tiehlicka.suse.cz> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2419 Lines: 64 On Mon, 18 Apr 2011, Michal Hocko wrote: > From: Michal Hocko > Subject: cpusets: initialize spread mem/slab rotor lazily > > Kosaki Motohiro raised a concern that copy_process is hot path and we do > not want to initialize cpuset_{mem,slab}_spread_rotor if they are not > used most of the time. > > I think that we should rather initialize it lazily when rotors are used > for the first time. > This will also catch the case when we set up spread mem/slab later. > > Signed-off-by: Michal Hocko > Reviewed-by: KOSAKI Motohiro Acked-by: David Rientjes Thanks Michal! > Index: linus_tree/kernel/cpuset.c > =================================================================== > --- linus_tree.orig/kernel/cpuset.c 2011-04-18 10:33:15.000000000 +0200 > +++ linus_tree/kernel/cpuset.c 2011-04-18 23:24:02.000000000 +0200 > @@ -2460,11 +2460,19 @@ static int cpuset_spread_node(int *rotor > > int cpuset_mem_spread_node(void) > { > + if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE) > + current->cpuset_mem_spread_rotor = > + node_random(¤t->mems_allowed); > + > return cpuset_spread_node(¤t->cpuset_mem_spread_rotor); > } > > int cpuset_slab_spread_node(void) > { > + if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE) > + current->cpuset_slab_spread_rotor = > + node_random(¤t->mems_allowed); > + > return cpuset_spread_node(¤t->cpuset_slab_spread_rotor); > } > > Index: linus_tree/kernel/fork.c > =================================================================== > --- linus_tree.orig/kernel/fork.c 2011-04-18 10:33:15.000000000 +0200 > +++ linus_tree/kernel/fork.c 2011-04-18 10:33:56.000000000 +0200 > @@ -1126,8 +1126,8 @@ static struct task_struct *copy_process( > mpol_fix_fork_child_flag(p); > #endif > #ifdef CONFIG_CPUSETS > - p->cpuset_mem_spread_rotor = node_random(&p->mems_allowed); > - p->cpuset_slab_spread_rotor = node_random(&p->mems_allowed); > + p->cpuset_mem_spread_rotor = NUMA_NO_NODE; > + p->cpuset_slab_spread_rotor = NUMA_NO_NODE; > #endif > #ifdef CONFIG_TRACE_IRQFLAGS > p->irq_events = 0; -- 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/