Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759452Ab3JORFH (ORCPT ); Tue, 15 Oct 2013 13:05:07 -0400 Received: from service87.mimecast.com ([91.220.42.44]:42369 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758902Ab3JORFF convert rfc822-to-8bit (ORCPT ); Tue, 15 Oct 2013 13:05:05 -0400 Date: Tue, 15 Oct 2013 18:05:07 +0100 From: Morten Rasmussen To: Peter Zijlstra Cc: "mingo@kernel.org" , "pjt@google.com" , "arjan@linux.intel.com" , "rjw@sisk.pl" , "dirk.j.brandewie@intel.com" , "vincent.guittot@linaro.org" , "alex.shi@linaro.org" , "preeti@linux.vnet.ibm.com" , "efault@gmx.de" , "corbet@lwn.net" , "tglx@linutronix.de" , Catalin Marinas , "linux-kernel@vger.kernel.org" , "linaro-kernel@lists.linaro.org" Subject: Re: [RFC][PATCH 0/7] Power-aware scheduling v2 Message-ID: <20131015170507.GR31039@e103034-lin> References: <1381511957-29776-1-git-send-email-morten.rasmussen@arm.com> <20131014133234.GM3081@twins.programming.kicks-ass.net> <20131014171541.GP31039@e103034-lin> <20131014173113.GB2675@laptop.programming.kicks-ass.net> MIME-Version: 1.0 In-Reply-To: <20131014173113.GB2675@laptop.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginalArrivalTime: 15 Oct 2013 17:04:58.0946 (UTC) FILETIME=[ADF4B220:01CEC9C8] X-MC-Unique: 113101518050109201 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2062 Lines: 48 On Mon, Oct 14, 2013 at 06:31:13PM +0100, Peter Zijlstra wrote: > On Mon, Oct 14, 2013 at 06:15:41PM +0100, Morten Rasmussen wrote: > > > In fact, I don't see anything except a random bunch of hooks without an > > > over-all picture of how to get less power used. > > > > I will follow up with a better description of the overall picture. The > > slides I linked to are not really self-explaining. > > I hadn't even noticed there were slides linked. In general I tend to > ignore external links -- patches should be descriptive enough to stand > on their own. Elaborating a bit more on the big picture and where we can go with this proposal, here are the main requirements: 1. A unified scheduler driven power policy, i.e. the scheduler drives DVFS/idle (as suggested by Ingo and hence this first set of patches). 2. Small task packing. Avoid spreading tasks under light workloads. In addition for big.LITTLE we need: 3. Task placement based cpu suitability. Associate task load ranges with each cpu to give task placement. Heavy tasks on big, small tasks on little. This patch set addresses part of 1, while 3 will follow soon. Point 2 is worked on by Vincent in collaboration with us. The power driver introduced in this set has a role in the solution to all three points. It serves as a unified platform power driver and the interface allows the scheduler to get highlevel feedback which cpufreq and cpuidle do not currently provide. Decisions about the power/performance trade-off will be made in the power driver guided by the hints from the scheduler. That allow platforms the freedom to do what they want with the hints including ignoring them completely (taking Arjan's previous comments into account). It will make the power driver much powerful than the current cpufreq/cpuidle drivers. 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/