Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757118Ab2HTPre (ORCPT ); Mon, 20 Aug 2012 11:47:34 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:57205 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752429Ab2HTPra (ORCPT ); Mon, 20 Aug 2012 11:47:30 -0400 MIME-Version: 1.0 In-Reply-To: <502C7F24.6020900@intel.com> References: <5028F12C.7080405@intel.com> <20120815161911.GA14534@srcf.ucam.org> <502C7F24.6020900@intel.com> Date: Mon, 20 Aug 2012 17:47:29 +0200 Message-ID: Subject: Re: [discussion]sched: a rough proposal to enable power saving in scheduler From: Vincent Guittot To: Alex Shi Cc: Matthew Garrett , Peter Zijlstra , Suresh Siddha , Arjan van de Ven , svaidy@linux.vnet.ibm.com, Ingo Molnar , Andrew Morton , Linus Torvalds , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1112 Lines: 27 On 16 August 2012 07:03, Alex Shi wrote: > On 08/16/2012 12:19 AM, Matthew Garrett wrote: > >> On Mon, Aug 13, 2012 at 08:21:00PM +0800, Alex Shi wrote: >> >>> power aware scheduling), this proposal will adopt the >>> sched_balance_policy concept and use 2 kind of policy: performance, power. >> >> Are there workloads in which "power" might provide more performance than >> "performance"? If so, don't use these terms. >> > > > Power scheme should no chance has better performance in design. A side effect of packing small tasks on one core is that you always use the core with the lowest C-state which will minimize the wake up latency so you can sometime get better results than performance mode which will try to use a other core in another cluster which will take more time to wake up that waiting for the end of the current task. Vincent -- 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/