Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932289AbaFIKTM (ORCPT ); Mon, 9 Jun 2014 06:19:12 -0400 Received: from mga03.intel.com ([143.182.124.21]:60243 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753950AbaFIKTK (ORCPT ); Mon, 9 Jun 2014 06:19:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,1001,1392192000"; d="scan'208";a="443246698" Date: Mon, 9 Jun 2014 10:15:16 +0800 From: Yuyang Du To: Morten Rasmussen Cc: Peter Zijlstra , Dirk Brandewie , "Rafael J. Wysocki" , "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: <20140609021516.GE22261@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> <20140609085952.GZ29593@e103034-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140609085952.GZ29593@e103034-lin> 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 Mon, Jun 09, 2014 at 09:59:52AM +0100, Morten Rasmussen wrote: > IMHO, the per-entity load-tracking does a fair job representing the task > compute capacity requirements. Sure it isn't perfect, particularly not > for memory bound tasks, but it is way better than not having any task > history at all, which was the case before. > > The story is more or less the same for performance scaling. It is not > taken into account at all in the scheduler at the moment. cpufreq is > actually messing up load-balancing decisions after task load-tracking > was introduced. Adding performance scaling awareness should only make > things better even if predictions are not accurate for all workloads. I > don't see why it shouldn't given the current state of energy-awareness > in the scheduler. > Optimized IPC is good for sure (with regard to pstate adjustment). My point is how it is practical to rightly correlate to scheduler and pstate power-efficiency. Put another way, with fixed workload, you really can do such a thing by offline running the workload several times to conclude with a very power-efficient solution which takes IPC into account. Actually, lots of people have done that in papers/reports (for SPECXXX or TPC-X for example). But I can't see how online realtime workload can be done like it. > > Currently, all freq governors take CPU utilization (load%) as the indicator > > (target), which can server both: workload and perf scaling. > > With a bunch of hacks on top to make it more reactive because the > current cpu utilization metric is not responsive enough to deal with > workload changes. That is at least the case for ondemand and interactive > (in Android). > To what end it is not responsive enough? And how it is related here? Thanks, 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/