Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755536Ab0DEQH7 (ORCPT ); Mon, 5 Apr 2010 12:07:59 -0400 Received: from mga12.intel.com ([143.182.124.36]:2485 "EHLO azsmga102.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755110Ab0DEQHz (ORCPT ); Mon, 5 Apr 2010 12:07:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.51,366,1267430400"; d="scan'208";a="262172153" Message-ID: <4BBA0AC5.1080905@linux.intel.com> Date: Mon, 05 Apr 2010 09:07:33 -0700 From: Arjan van de Ven User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Dominik Brodowski , Alan Stern , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Dmitry Torokhov Subject: Re: A few questions and issues with dynticks, NOHZ and powertop References: <20100403223328.GA4507@comet.dominikbrodowski.net> <20100404163924.GA18428@comet.dominikbrodowski.net> <20100404204725.GC2644@linux.vnet.ibm.com> <20100404233702.GA24102@linux.vnet.ibm.com> <4BB95C85.80205@linux.intel.com> <20100405042222.GD2644@linux.vnet.ibm.com> <4BB9F657.4050901@linux.intel.com> <20100405151401.GA2525@linux.vnet.ibm.com> In-Reply-To: <20100405151401.GA2525@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 891 Lines: 20 On 4/5/2010 8:14, Paul E. McKenney wrote: > So the main issue is that for many workloads, it is best to run full bore > and get done quickly, thus allowing the entire machine to be powered down? yep > > If so, it seems likely that there would be some workloads that were sometimes > unable to use all the CPUs, in which case shutting down (idling, offlining, > dyntick-idling, whatever) the excess CPUs might nevertheless be the right > thing to do. but the point is that the normal scheduler + idle behavior gives you exactly that in a natural way ! If you don't have enough work (tasks) to keep all cores busy, the others are and stay idle. -- 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/