Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S945585AbcJSPmI (ORCPT ); Wed, 19 Oct 2016 11:42:08 -0400 Received: from mail-qt0-f170.google.com ([209.85.216.170]:34880 "EHLO mail-qt0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S943473AbcJSPmG (ORCPT ); Wed, 19 Oct 2016 11:42:06 -0400 MIME-Version: 1.0 In-Reply-To: <550def7c-a0e6-b2ae-7bef-aeec6f068cfb@arm.com> References: <20161014151827.GA10379@linaro.org> <2bb765e7-8a5f-c525-a6ae-fbec6fae6354@canonical.com> <20161017090903.GA11962@linaro.org> <4e15ad55-beeb-e860-0420-8f439d076758@arm.com> <20161017131952.GR3117@twins.programming.kicks-ass.net> <94cc6deb-f93e-60ec-5834-e84a8b98e73c@arm.com> <20161018090747.GW3142@twins.programming.kicks-ass.net> <20161018103412.GT3117@twins.programming.kicks-ass.net> <20161018115651.GA20956@linaro.org> <550def7c-a0e6-b2ae-7bef-aeec6f068cfb@arm.com> From: Vincent Guittot Date: Wed, 19 Oct 2016 13:25:28 +0200 Message-ID: Subject: Re: [v4.8-rc1 Regression] sched/fair: Apply more PELT fixes To: Dietmar Eggemann Cc: Peter Zijlstra , Joseph Salisbury , Ingo Molnar , Linus Torvalds , Thomas Gleixner , LKML , Mike Galbraith , omer.akram@canonical.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id u9JFgFPY018393 Content-Length: 2184 Lines: 58 On 19 October 2016 at 11:46, Dietmar Eggemann wrote: > On 18/10/16 12:56, Vincent Guittot wrote: >> Le Tuesday 18 Oct 2016 à 12:34:12 (+0200), Peter Zijlstra a écrit : >>> On Tue, Oct 18, 2016 at 11:45:48AM +0200, Vincent Guittot wrote: >>>> On 18 October 2016 at 11:07, Peter Zijlstra wrote: > > [...] > >> >> The patch below fixes the issue on my platform: >> >> Dietmar, Omer can you confirm that this fix the problem of your platform too ? > > It fixes this broken BIOS issue on my T430 ( cpu_possible_mask > > cpu_online_mask). I ran the original test with the cpu hogs (stress -c > 4). Launch time of applications becomes normal again. > > Tested-by: Dietmar Eggemann Thanks > > But this test only makes sure that we don't see any ghost contribution > (from non-existing cpus) any more. > > We should study the tg->se[i]->avg.load_avg for the hierarchy of tg's > (with the highest tg having a task enqueued) a little bit more, with and > without your v5 'sched: reflect sched_entity move into task_group's load'. Can you elaborate ? Vincent > >> --- >> kernel/sched/fair.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 8b03fb5..89776ac 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -690,7 +690,14 @@ void init_entity_runnable_average(struct sched_entity *se) >> * will definitely be update (after enqueue). >> */ >> sa->period_contrib = 1023; >> - sa->load_avg = scale_load_down(se->load.weight); >> + /* >> + * Tasks are intialized with full load to be seen as heavy task until >> + * they get a chance to stabilize to their real load level. >> + * group entity are intialized with null load to reflect the fact that >> + * nothing has been attached yet to the task group. >> + */ >> + if (entity_is_task(se)) >> + sa->load_avg = scale_load_down(se->load.weight); >> sa->load_sum = sa->load_avg * LOAD_AVG_MAX; >> /* >> * At this point, util_avg won't be used in select_task_rq_fair anyway