From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuyang Du Subject: Re: [RFCv2 PATCH 00/23] sched: Energy cost model for energy-aware scheduling Date: Mon, 7 Jul 2014 03:05:23 +0800 Message-ID: <20140706190523.GA12113@intel.com> References: <1404404770-323-1-git-send-email-morten.rasmussen@arm.com> <20140703231950.GA4881@intel.com> <20140704110612.GA6120@e103034-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mga09.intel.com ([134.134.136.24]:39485 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752024AbaGGDIW (ORCPT ); Sun, 6 Jul 2014 23:08:22 -0400 Content-Disposition: inline In-Reply-To: <20140704110612.GA6120@e103034-lin> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Morten Rasmussen Cc: "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , "peterz@infradead.org" , "mingo@kernel.org" , "rjw@rjwysocki.net" , "vincent.guittot@linaro.org" , "daniel.lezcano@linaro.org" , "preeti@linux.vnet.ibm.com" , Dietmar Eggemann , "pjt@google.com" Hi Morten, Thanks, got it. Then another question, On Fri, Jul 04, 2014 at 12:06:13PM +0100, Morten Rasmussen wrote: > The patch set essentially puts tasks where it is most energy-efficient > guided by the platform energy model. That should benefit any platform, > SMP and big.LITTLE. That is at least the goal. > I understand energy_diff_* functions are based on the energy model (though I have not dived into the detail of how you change load balancing based on energy_diff_*). Speaking of the engergy model, I am not sure why elaborate "imprecise" energy numbers do a better job than only a general statement: higher freq, more cap, and more power. Even for big.LITTLE systems, big and little CPUs also follow that statement respectively. Then it is just a matter of where to place tasks between them. Under such, the energy model might be useful, but still probably cpu_power_orig (from Vincent) might be enough. Thanks, Yuyang