Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754521AbYAINVW (ORCPT ); Wed, 9 Jan 2008 08:21:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753848AbYAINVH (ORCPT ); Wed, 9 Jan 2008 08:21:07 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:53386 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753415AbYAINVF (ORCPT ); Wed, 9 Jan 2008 08:21:05 -0500 Date: Wed, 9 Jan 2008 14:20:14 +0100 From: Ingo Molnar To: "Siddha, Suresh B" , discuss@LessWatts.org, Linux-pm mailing list , Linux Kernel , Dipankar Sarma , venkatesh.pallipadi@intel.com, tglx@linutronix.de, Arjan van de Ven , Gautham R Shenoy , Chanda Sethia Subject: Re: Analysis of sched_mc_power_savings Message-ID: <20080109132014.GF27196@elte.hu> References: <20080108173815.GA7793@dirshya.in.ibm.com> <20080108212400.GA8903@linux-os.sc.intel.com> <20080109111302.GC7793@dirshya.in.ibm.com> <20080109113507.GA29721@elte.hu> <20080109122847.GA28955@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080109122847.GA28955@dirshya.in.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1257 Lines: 29 * Vaidyanathan Srinivasan wrote: > I will watch this during the experiments. I have been using klog > application to dump relayfs data. I did run powertop and top as well, > I will bind them to certain CPUs and isolate their impact. > > I believe the margin of error would be less since all the measurement > tasks sleep for long duration. ok, long duration ought to be enough. i think a possible explanation of your observtions would be this: sleepy workloads are affected more by the wakeup logic, and most of the power-savings works via runtime balancing. So perhaps try to add some SD_POWERSAVINGS_BALANCE logic to try_to_wake_up()? I think waking up on the same CPU where it went to sleep is the most power-efficient approach in general. (or always waking up where the wakee runs - this should be measured.) Right now try_to_wake_up() tries to spread out load opportunistically, which is throughput-maximizing but it's arguably not very power conscious. 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/