Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755565AbaFII1s (ORCPT ); Mon, 9 Jun 2014 04:27:48 -0400 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:22453 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755221AbaFII1o (ORCPT ); Mon, 9 Jun 2014 04:27:44 -0400 Date: Mon, 9 Jun 2014 09:27:39 +0100 From: Morten Rasmussen To: Nicolas Pitre Cc: Ingo Molnar , Peter Zijlstra , Yuyang Du , Dirk Brandewie , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , "linux-pm@vger.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: <20140609082739.GY29593@e103034-lin> References: <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> <20140606121305.GA8571@gmail.com> <20140606122740.GA9318@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Sat, Jun 07, 2014 at 03:33:58AM +0100, Nicolas Pitre wrote: > On Fri, 6 Jun 2014, Ingo Molnar wrote: > > > In any case, even with turbo frequencies, switching power use is > > probably an order of magnitude higher than leakage current power use, > > on any marketable chip, so we should concentrate on being able to > > cover this first order effect (P/work ~ V^2), before considering any > > second order effects (leakage current). > > Just so that people are aware... We'll have to introduce thermal > constraint management into the scheduler mix as well at some point. > Right now what we have is an ad hoc subsystem that simply monitors > temperature and apply crude cooling strategies when some thresholds are > met. But a better strategy would imply thermal "provisioning". There is already work going on to improve thermal management: http://lwn.net/Articles/599598/ The proposal is based on power/energy models (too). The goal is to allocate power intelligently based on performance requirements. While it is related to energy-aware scheduling and I fully agree that it is something we need to consider, I think it is worth developing the two ideas in parallel and look at sharing things like the power model later once things mature. Energy-aware scheduling is complex enough on its own to keep us entertained for a while :-) Morten -- 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/