From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755110AbbCYSO2 (ORCPT ); Wed, 25 Mar 2015 14:14:28 -0400 Received: from casper.infradead.org ([85.118.1.10]:44723 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753953AbbCYSOZ (ORCPT ); Wed, 25 Mar 2015 14:14:25 -0400 Date: Wed, 25 Mar 2015 19:14:13 +0100 From: Peter Zijlstra To: Juri Lelli Cc: Morten Rasmussen , "mingo@redhat.com" , "vincent.guittot@linaro.org" , Dietmar Eggemann , "yuyang.du@intel.com" , "preeti@linux.vnet.ibm.com" , "mturquette@linaro.org" , "nico@linaro.org" , "rjw@rjwysocki.net" , "linux-kernel@vger.kernel.org" Subject: Re: [RFCv3 PATCH 33/48] sched: Energy-aware wake-up task placement Message-ID: <20150325181413.GT21418@twins.programming.kicks-ass.net> References: <1423074685-6336-1-git-send-email-morten.rasmussen@arm.com> <1423074685-6336-34-git-send-email-morten.rasmussen@arm.com> <20150324163503.GZ23123@twins.programming.kicks-ass.net> <5512F7F2.2010705@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5512F7F2.2010705@arm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 25, 2015 at 06:01:22PM +0000, Juri Lelli wrote: > Yes and no, IMHO. It makes perfect sense to trigger cpufreq on the > target_cpu's freq domain, as we know that we are going to add p's > utilization there. Fair point; I mainly wanted to start this discussion so that seems to have been a success :-) > Anyway, I was thinking that we could just > rely on triggering points in {en,de}queue_task_fair and task_tick_fair. > We end up calling one of them every time we wake-up a task, perform > a load balancing decision or just while running the task itself > (we have to react to tasks phase changes). This way we should be > able to reduce the number of triggering points and be more general > at the same time. The one worry I have with that is that it might need to re-compute which P state to request, where in the above (now trimmed quoted) code we already figured out which P state we needed to be in, any hook in enqueue would have forgotten that. > > So does it make sense to at least put in the right hooks now? I realize > > we'll likely take cpufreq out back and feed it to the bears but > > something managing P states will be there whatever we'll call the new > > fangled thing and this would be the place to hook it still. > > > > We should be able to clean up and post something along this line > fairly soon. Grand!