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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 316BCC2BA19 for ; Tue, 14 Apr 2020 17:21:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 154CE206A2 for ; Tue, 14 Apr 2020 17:21:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407624AbgDNRVd (ORCPT ); Tue, 14 Apr 2020 13:21:33 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:33659 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407594AbgDNRV3 (ORCPT ); Tue, 14 Apr 2020 13:21:29 -0400 Received: by mail-wr1-f66.google.com with SMTP id a25so15353474wrd.0 for ; Tue, 14 Apr 2020 10:21:26 -0700 (PDT) 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:user-agent; bh=pFmpb+RA+NWz9T4WQIzSSblNv9ya5RwMO1G2Lr5Br/c=; b=E6pl8bRclDUQzmGxEzTlKzs+PpS3PN26S3O2BW8s/c+jjR1SADr/4GISXuCvRQ8sDZ Uq0CvTqg/lDvhhrCnd3GLiMhZB89ZdSg+yAlmsQYeNP8Osf/ryS6rn0QvhdHQf/pF7nr Nq2r0GZ50CdTabInS4ypwtxqZiG5vqP1iWrCq1trpMb2wpPV9AFWLtE8UCPp3OeARDeX snwgmU76EjgYadBuvTiAYcf+8V+ljniluq81u2pAfS7JaWEqr8WnuJCUcpytaewLt9dZ X2KSVDOF1BJ/0Uv9kpgBuimnFLwhsHb5IftPetiXuFXOgNn16kF7+5V79NpYInGWNwNu ZNFA== X-Gm-Message-State: AGi0PubeNcqRRfhkUy0X0D+1TvLepZLPL7yWSVyWyS/FeKmxqvhd6RRn gVVozr5BX548ujyLQUzQgBY= X-Google-Smtp-Source: APiQypKGLMd4Io+mmJCD/aE71mw75UTb89hD2sdyZ51tFIcs+6M14eUwDvUS4XBySaMGdiIp8wTneg== X-Received: by 2002:a5d:6091:: with SMTP id w17mr21891200wrt.382.1586884886048; Tue, 14 Apr 2020 10:21:26 -0700 (PDT) Received: from darkstar ([51.154.17.58]) by smtp.gmail.com with ESMTPSA id j135sm20463515wmj.46.2020.04.14.10.21.23 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 14 Apr 2020 10:21:25 -0700 (PDT) Date: Tue, 14 Apr 2020 19:21:20 +0200 From: Patrick Bellasi 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, 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: <20200414172120.GA20442@darkstar> 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> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14-Apr 17:13, 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. Right, good catch. Thanks. > 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 Fixes: 1a00d999971c ("sched/uclamp: Set default clamps for RT tasks") Reviewed-by: Patrick Bellasi > --- > 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); > - > uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false); > } > } > -- > 2.26.0.110.g2183baf09c-goog > -- #include Patrick Bellasi