Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755220AbaFKCjB (ORCPT ); Tue, 10 Jun 2014 22:39:01 -0400 Received: from mga01.intel.com ([192.55.52.88]:44658 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751619AbaFKCi7 (ORCPT ); Tue, 10 Jun 2014 22:38:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="353374253" Date: Wed, 11 Jun 2014 02:35:05 +0800 From: Yuyang Du To: Peter Zijlstra Cc: Dirk Brandewie , "Rafael J. Wysocki" , Morten Rasmussen , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , "mingo@kernel.org" , "vincent.guittot@linaro.org" , "daniel.lezcano@linaro.org" , "preeti@linux.vnet.ibm.com" , Dietmar Eggemann , len.brown@intel.com, jacob.jun.pan@linux.intel.com Subject: Re: [RFC PATCH 06/16] arm: topology: Define TC2 sched energy and provide it to scheduler Message-ID: <20140610183505.GC5487@intel.com> References: <20140604172712.GJ13930@laptop.programming.kicks-ass.net> <2484761.vkWavnsDx3@vostro.rjw.lan> <20140605065205.GA3213@twins.programming.kicks-ass.net> <539086B3.2010804@gmail.com> <20140605202930.GA15484@intel.com> <20140606080543.GR6758@twins.programming.kicks-ass.net> <20140606003520.GB22261@intel.com> <20140606105036.GQ3213@twins.programming.kicks-ass.net> <20140607232628.GC22261@intel.com> <20140610101622.GB6758@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140610101622.GB6758@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 10, 2014 at 12:16:22PM +0200, Peter Zijlstra wrote: > What other target would you optimize for? The purpose here is to build > an energy aware scheduler, one that schedules tasks so that the total > amount of energy, for the given amount of work, is minimal. > > So we can't measure in Watt, since if we forced the CPU into the lowest > P-state (or even C-state for that matter) work would simply not > complete. So we need a complete energy term. > > Now. IPC is instructions/cycle, Watt is Joule/second, so IPC/Watt is > > instructions second > ------------ * ------ ~ instructions / joule > cycle joule > > Seeing how both cycles and seconds are time units. > > So for any given amount of instructions, the work needs to be done, we > want the minimal amount of energy consumed, and IPC/Watt is the natural > metric to measure this over an entire workload. Ok, I understand. Whether we take IPC/watt as an input metric in scheduler or as a goal for scheduler, we definitely need to try both. Thanks, Peter. Yuyang -- 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/