Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754946AbaFINWx (ORCPT ); Mon, 9 Jun 2014 09:22:53 -0400 Received: from mail-qa0-f41.google.com ([209.85.216.41]:60575 "EHLO mail-qa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753298AbaFINWv (ORCPT ); Mon, 9 Jun 2014 09:22:51 -0400 Date: Mon, 9 Jun 2014 09:22:49 -0400 (EDT) From: Nicolas Pitre To: Morten Rasmussen 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 In-Reply-To: <20140609082739.GY29593@e103034-lin> Message-ID: 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> <20140609082739.GY29593@e103034-lin> User-Agent: Alpine 2.11 (LFD 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 9 Jun 2014, Morten Rasmussen wrote: > 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. Ah, great! I missed that. > 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 :-) Absolutely. This is why I said "at some point". Nicolas -- 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/