Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755073AbZD0Dwx (ORCPT ); Sun, 26 Apr 2009 23:52:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752904AbZD0Dwn (ORCPT ); Sun, 26 Apr 2009 23:52:43 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:35862 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752675AbZD0Dwn (ORCPT ); Sun, 26 Apr 2009 23:52:43 -0400 Date: Mon, 27 Apr 2009 05:52:16 +0200 From: Ingo Molnar To: Vaidyanathan Srinivasan Cc: Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Peter Zijlstra , Arjan van de Ven , Dipankar Sarma , Balbir Singh , Vatsa , Gautham R Shenoy , Andi Kleen , Gregory Haskins , Mike Galbraith , Thomas Gleixner , Arun Bharadwaj Subject: Re: [RFC PATCH v1 0/3] Saving power by cpu evacuation using sched_mc=n Message-ID: <20090427035216.GD10087@elte.hu> References: <20090426204029.17495.46609.stgit@drishya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090426204029.17495.46609.stgit@drishya.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) 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: 1222 Lines: 34 * Vaidyanathan Srinivasan wrote: > Test results for ebizzy 8 threads at various sched_mc settings has > been summarised with relative values below. The test platform is > dual socket quad core x86 system (pre-Nehalem). > > -------------------------------------------------------- > sched_mc No Cores Performance AvgPower > used Records/sec (Watts) > -------------------------------------------------------- > 0 8 1.00x 1.00y > 1 8 1.02x 1.01y > 2 8 0.83x 1.01y > 3 7 0.86x 0.97y > 4 6 0.76x 0.92y > 5 4 0.72x 0.82y > -------------------------------------------------------- Looks like we want the kernel default to be sched_mc=1 ? Regarding the values for 2...5 - is the AvgPower column time normalized or workload normalized? If it's time normalized then it appears there's no power win here at all: we'd be better off by throttling the workload directly (by injecting sleeps or something like that), right? 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/