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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 AC9F3C352AA for ; Tue, 1 Oct 2019 17:12:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D9F82086A for ; Tue, 1 Oct 2019 17:12:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728536AbfJARM3 (ORCPT ); Tue, 1 Oct 2019 13:12:29 -0400 Received: from foss.arm.com ([217.140.110.172]:54798 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725792AbfJARM2 (ORCPT ); Tue, 1 Oct 2019 13:12:28 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 483B4337; Tue, 1 Oct 2019 10:12:28 -0700 (PDT) Received: from [10.1.194.37] (e113632-lin.cambridge.arm.com [10.1.194.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0E5283F706; Tue, 1 Oct 2019 10:12:26 -0700 (PDT) Subject: Re: [PATCH v3 08/10] sched/fair: use utilization to select misfit task To: Vincent Guittot , linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org Cc: pauld@redhat.com, srikar@linux.vnet.ibm.com, quentin.perret@arm.com, dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com, hdanton@sina.com References: <1568878421-12301-1-git-send-email-vincent.guittot@linaro.org> <1568878421-12301-9-git-send-email-vincent.guittot@linaro.org> From: Valentin Schneider Message-ID: Date: Tue, 1 Oct 2019 18:12:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1568878421-12301-9-git-send-email-vincent.guittot@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/09/2019 08:33, Vincent Guittot wrote: > utilization is used to detect a misfit task but the load is then used to > select the task on the CPU which can lead to select a small task with > high weight instead of the task that triggered the misfit migration. > > Signed-off-by: Vincent Guittot > Acked-by: Valentin Schneider > --- > kernel/sched/fair.c | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index a7c8ee6..acca869 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7429,14 +7429,8 @@ static int detach_tasks(struct lb_env *env) > break; > > case migrate_misfit: > - load = task_h_load(p); > - > - /* > - * utilization of misfit task might decrease a bit > - * since it has been recorded. Be conservative in the > - * condition. > - */ > - if (load < env->imbalance) > + /* This is not a misfit task */ > + if (task_fits_capacity(p, capacity_of(env->src_cpu))) > goto next; > > env->imbalance = 0; > Following my comment in [1], if you can't squash that in patch 04 then perhaps you could add that to this change: --- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1fac444a4831..d09ce304161d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8343,7 +8343,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s if (busiest->group_type == group_misfit_task) { /* Set imbalance to allow misfit task to be balanced. */ env->balance_type = migrate_misfit; - env->imbalance = busiest->group_misfit_task_load; + env->imbalance = 1; return; } --- Reason being we don't care about the load (anymore), we just want a nonzero imbalance value, so might as well assign something static. [1]: https://lore.kernel.org/r/74bb33d7-3ba4-aabe-c7a2-3865d5759281@arm.com