Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424413AbWKJVmo (ORCPT ); Fri, 10 Nov 2006 16:42:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966118AbWKJVmo (ORCPT ); Fri, 10 Nov 2006 16:42:44 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:23242 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S966116AbWKJVmn (ORCPT ); Fri, 10 Nov 2006 16:42:43 -0500 Date: Fri, 10 Nov 2006 22:42:08 +0100 From: Ingo Molnar To: Christoph Lameter Cc: "Chen, Kenneth W" , "Siddha, Suresh B" , akpm@osdl.org, mm-commits@vger.kernel.org, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org Subject: Re: + sched-use-tasklet-to-call-balancing.patch added to -mm tree Message-ID: <20061110214208.GA23456@elte.hu> References: <000001c70490$01cea4b0$8bc8180a@amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i X-ELTE-SpamScore: -2.8 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.8 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] -0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1484 Lines: 43 * Christoph Lameter wrote: > On a 8p system: > > I) Percent of ticks where load balancing was found to be required > > II) Percent of ticks where we attempted load balancing > but we found that we need to try again due to load balancing > in progress elsewhere (This increases (I) since we found that > load balancing was required but we decided to defer. Tasklet > was not invoked). > > I) II) > Boot: 70% ~1% > AIM7: 30% 2% > Idle: 50% <0.5% > > 256p: > I) II) > Boot: 80% 30% > AIM7: 90% 30% > Idle: 95% 30% nice measurements and interesting results. note that with a tasklet a 'retry' will often be done on the /same/ CPU that was running the tasklet when we tried to schedule it. I.e. such a 'collision' will result not only in the 'loss' of the local rebalance event, but also causes /another/ rebalance event on the remote CPU. so a better model would be the trylock model i suggested in the previous mail: to just lose the rebalance events upon collision and not cause extra work on the remote CPU. I'd also suggest to keep the rebalancing code under the irqs-off section, like it is currently - only do it conditional on trylock success. Do you think that would work? Ingo - 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/