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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1A321C2BA19 for ; Tue, 14 Apr 2020 16:23:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E2E1E2075E for ; Tue, 14 Apr 2020 16:23:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="BtbOfks/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391421AbgDNQXm (ORCPT ); Tue, 14 Apr 2020 12:23:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S2391389AbgDNQVb (ORCPT ); Tue, 14 Apr 2020 12:21:31 -0400 Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E93D7C061A0C for ; Tue, 14 Apr 2020 09:21:30 -0700 (PDT) Received: by mail-qk1-x743.google.com with SMTP id l25so13888906qkk.3 for ; Tue, 14 Apr 2020 09:21:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=qO1q6P7urcC/fAzNLncA31bdH5lHcyLQ+KsgAdpa1ZI=; b=BtbOfks/3jhe+uiHkAoG+/h6Du7PsbYryI8LlB8CftizsftXCwTaJpSReBQMxv3YND E3QFB2U1zdAjFRYgrhS2A/dQigxIw72J9gXp+lSyR9EfNJLi/XZwCgYoQ0Mn7D5+uMka cvaS3FFJaJ3V5YRmsdkVgYQAWCZuDcHzNT/Q8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=qO1q6P7urcC/fAzNLncA31bdH5lHcyLQ+KsgAdpa1ZI=; b=EMbeHQNpk2nY/te8YpQ5bBaWfnHuq3sTvyzMG9eQGgTKS8TtORfakGgJdHrxN0SYc6 InoBLqGd2ktQWQm55VJc2sFu5fuIMgP6oZbq3Zjg6GynrEk5RexGXilmcg6Q2vUXVIvJ /Nj0wTJ+IGG9X8q8C914/7vs3Bp4htz3HBpeRTx31VvobE4NvQ5FhdPtW7uPpVBK9NmE jOOm46lMh2lStyAM/c9IllOL2ObwJIQqjDk8k+Pcah0+wMXUMlcJNAn8yTI6yYVkaoOL xRsS8IU8HDNiTau9JYghTYzU3MQ6bR4dLjy914lorM28adMw6QvtY+wh50G2lc6tpu19 yytA== X-Gm-Message-State: AGi0Puao0Qr7DEpT3gXsy38o08UhpHOEFk0aNgUlERpIfxensS3Bd4/O /uah7D9+ueNkwrH1eFN5xgXeqA== X-Google-Smtp-Source: APiQypKftdFMdNybcSMayepMnxyaCqgT55vJLwQmFq+2FmywXKI+awCZNld1vohh2HOQ2/MOEJaDFQ== X-Received: by 2002:a37:4e0a:: with SMTP id c10mr16859737qkb.242.1586881289880; Tue, 14 Apr 2020 09:21:29 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id m187sm656423qkc.30.2020.04.14.09.21.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2020 09:21:29 -0700 (PDT) Date: Tue, 14 Apr 2020 12:21:28 -0400 From: Joel Fernandes To: Quentin Perret Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, ctheegal@codeaurora.org, dianders@chromium.org, patrick.bellasi@matbug.net, valentin.schneider@arm.com, qais.yousef@arm.com, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH] sched/core: Fix reset-on-fork from RT with uclamp Message-ID: <20200414162128.GA66453@google.com> References: <20200414161320.251897-1-qperret@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200414161320.251897-1-qperret@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 14, 2020 at 05:13:20PM +0100, Quentin Perret wrote: > uclamp_fork() resets the uclamp values to their default when the > reset-on-fork flag is set. It also checks whether the task has a RT > policy, and sets its uclamp.min to 1024 accordingly. However, during > reset-on-fork, the task's policy is lowered to SCHED_NORMAL right after, > hence leading to an erroneous uclamp.min setting for the new task if it > was forked from RT. > > Fix this by removing the unnecessary check on rt_policy() in > uclamp_fork() as this doesn't make sense if the reset-on-fork flag is > set. > > Reported-by: Chitti Babu Theegala > Signed-off-by: Quentin Perret > --- > kernel/sched/core.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 3a61a3b8eaa9..9ea3e484eea2 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1234,10 +1234,6 @@ static void uclamp_fork(struct task_struct *p) > for_each_clamp_id(clamp_id) { > unsigned int clamp_value = uclamp_none(clamp_id); > > - /* By default, RT tasks always get 100% boost */ > - if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) > - clamp_value = uclamp_none(UCLAMP_MAX); > - Shouldn't this be conditional on p->sched_reset_on_fork instead of deleting the code? thanks, - Joel > uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false); > } > } > -- > 2.26.0.110.g2183baf09c-goog >