From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752131AbdI2NDm (ORCPT ); Fri, 29 Sep 2017 09:03:42 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:43404 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751813AbdI2NDl (ORCPT ); Fri, 29 Sep 2017 09:03:41 -0400 Date: Fri, 29 Sep 2017 14:03:36 +0100 From: Morten Rasmussen To: Peter Zijlstra Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, tj@kernel.org, josef@toxicpanda.com, torvalds@linux-foundation.org, vincent.guittot@linaro.org, efault@gmx.de, pjt@google.com, clm@fb.com, dietmar.eggemann@arm.com, bsegall@google.com, yuyang.du@intel.com Subject: Re: [PATCH -v2 02/18] sched/fair: Add comment to calc_cfs_shares() Message-ID: <20170929130336.GB16286@e105550-lin.cambridge.arm.com> References: <20170901132059.342024223@infradead.org> <20170901132748.083733695@infradead.org> <20170928100303.GA962@e105550-lin.cambridge.arm.com> <20170929113500.kryvylelokyohssz@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170929113500.kryvylelokyohssz@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 29, 2017 at 01:35:00PM +0200, Peter Zijlstra wrote: > On Thu, Sep 28, 2017 at 11:03:03AM +0100, Morten Rasmussen wrote: > > IIUC, if grq->avg.load_avg > grq->load.weight, i.e. you have blocked > > tasks, you can end up with underestimating the ge->load.weight for some > > of the group entities lead to \Sum ge->load.weight < tg->weight. > > Ah yes, you're right. However, if you look at the end of the series we > actually end up with using: > > max(grq->load.weight, grq->avg.load_avg) > > Which I suppose makes it true again. Yes, with the next patch in the series, underestimation is no longer possible.