Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754847Ab2HUBGC (ORCPT ); Mon, 20 Aug 2012 21:06:02 -0400 Received: from mga02.intel.com ([134.134.136.20]:52395 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754160Ab2HUBGA (ORCPT ); Mon, 20 Aug 2012 21:06:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.77,799,1336374000"; d="scan'208";a="183320511" Message-ID: <5032DED6.9090709@intel.com> Date: Tue, 21 Aug 2012 09:05:26 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111229 Thunderbird/9.0 MIME-Version: 1.0 To: Vincent Guittot 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" Subject: Re: [discussion]sched: a rough proposal to enable power saving in scheduler References: <5028F12C.7080405@intel.com> <20120815161911.GA14534@srcf.ucam.org> <502C7F24.6020900@intel.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1269 Lines: 32 On 08/20/2012 11:47 PM, Vincent Guittot wrote: > 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. > Sure. some scenario packing tasks into smaller domain will bring performance benefit. -- 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/