From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9563C35647 for ; Fri, 21 Feb 2020 10:40:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 968FF20722 for ; Fri, 21 Feb 2020 10:40:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727513AbgBUKkY (ORCPT ); Fri, 21 Feb 2020 05:40:24 -0500 Received: from mx2.suse.de ([195.135.220.15]:54242 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726976AbgBUKkY (ORCPT ); Fri, 21 Feb 2020 05:40:24 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 3DA21AC5C; Fri, 21 Feb 2020 10:40:22 +0000 (UTC) Date: Fri, 21 Feb 2020 10:40:18 +0000 From: Mel Gorman To: Vincent Guittot Cc: Valentin Schneider , Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , linux-kernel , Phil Auld , Parth Shah , Hillf Danton Subject: Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal Message-ID: <20200221104018.GR3420@suse.de> References: <20200214152729.6059-5-vincent.guittot@linaro.org> <20200219125513.8953-1-vincent.guittot@linaro.org> <9fe822fc-c311-2b97-ae14-b9269dd99f1e@arm.com> <20200221090448.GQ3420@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 21, 2020 at 10:25:27AM +0100, Vincent Guittot wrote: > On Fri, 21 Feb 2020 at 10:04, Mel Gorman wrote: > > > > On Thu, Feb 20, 2020 at 04:11:18PM +0000, Valentin Schneider wrote: > > > On 20/02/2020 14:36, Vincent Guittot wrote: > > > > I agree that setting by default to SCHED_CAPACITY_SCALE is too much > > > > for little core. > > > > The problem for little core can be fixed by using the cpu capacity instead > > > > > > > > > > So that's indeed better for big.LITTLE & co. Any reason however for not > > > aligning with the initialization of util_avg ? > > > > > > With the default MC imbalance_pct (117), it takes 875 utilization to make > > > a single CPU group (with 1024 capacity) overloaded (group_is_overloaded()). > > > For a completely idle CPU, that means forking at least 3 tasks (512 + 256 + > > > 128 util_avg) > > > > > > With your change, it only takes 2 tasks. I know I'm being nitpicky here, but > > > I feel like those should be aligned, unless we have a proper argument against > > > it - in which case this should also appear in the changelog with so far only > > > mentions issues with util_avg migration, not the fork time initialization. > > > > > > > So, what is the way forward here? Should this patch be modified now, > > a patch be placed on top or go with what we have for the moment that > > works for symmetric CPUs and deal with the asym case later? > > > > I do not have any asym systems at all so I've no means of checking > > whether there is a problem or not. > > I'm going to send a new version at least for patch 4 and 5 using > cpu_scale as initial value and fixing update_sg_wakeup_stats() > No problem. FWIW, when I see them, I'll slot them in and rerun the tests as the previous results will be invalidated. Obviously the asym case will not be tested by me but I imagine you or Valentin have that covered. Thanks. -- Mel Gorman SUSE Labs