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=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 52EAAC2BB85 for ; Wed, 15 Apr 2020 08:20:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A7B420784 for ; Wed, 15 Apr 2020 08:20:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="EQaEFEvL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2635828AbgDOIUX (ORCPT ); Wed, 15 Apr 2020 04:20:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2635575AbgDOIUH (ORCPT ); Wed, 15 Apr 2020 04:20:07 -0400 Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05425C061A0C for ; Wed, 15 Apr 2020 01:20:06 -0700 (PDT) Received: by mail-wm1-x343.google.com with SMTP id z6so17857583wml.2 for ; Wed, 15 Apr 2020 01:20:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=tI6bF5NlaH6VP+qupCyijc9MdFpBjDaskO3oNma/yVo=; b=EQaEFEvL8a8nS0NGknzoERg+UJatb0uLaxOlI4m8PDNNa9XN/UJ77yfywyfYDxZb9M RYPtUHGszY/AwYsfORLlo/bwtANsiGcjTWV/4E3S4gtUIMjtEM96yILnaAOl7xCt4VFQ IcJOK13Rbx4DhYG1fdKPJvYb+5PDVnKFiKGtCXrFwVZ7RaJD5Gxmug26QuGkEDqV0Mdr WFiMGPM9i5S9s0dg5XrSQyPfDy89PFOjeP1FPFvyYifIZbXrelFNfGBc5p630xGyPFWC PpwLG8kxNrr96Avfa+Kr+JZhVEM4qDqnVrDbJyydYKH4CTNe8hK7DRbWaruR7ePh51jn VNqA== 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=tI6bF5NlaH6VP+qupCyijc9MdFpBjDaskO3oNma/yVo=; b=Lcv2QH4zd+cEDU91n54sNUdEYPjJPkmG2RsapIZ0za1Bo0TydcYyDKQgd5Ydy4x76p N7A/bBU5GYNfjdda4vfmq2zUbdW8+ilpwQ31xXCUuLYePjSj9htBPxoUmQkDnzakmADz mwfgAWWX3U3YMwDwKnUl+DD4to++E2da362PwrMaiSdGO1rBRxc07hqasNt3sZrDyFls dfHB/LwLYmk8eYzyDzpFfjng5p7olyORNsEaFvOmLifRIt5OvSc107e5toz3/IoO6plk uOdLN3qFPGEkuoVALnnaUlnvMamgGuoUixoLHpu8s9U+DA8Fla4P7gu1YEJHEOotw2kl M2xA== X-Gm-Message-State: AGi0PuYo/eqVQlJU12wfmIj6KVkzDGveIGMlzsE5sFT4cjZCD2XLUAvC x5rpcn3WIDjGOR5avjnOBNZz2Q== X-Google-Smtp-Source: APiQypLfCVgV0tOWD0TIjssd9/GA8YX2l0BlHT490ZXW6wAL/ti9Z2T/rtGZQ9qeywYAilxhL40vWA== X-Received: by 2002:a1c:4d18:: with SMTP id o24mr3721578wmh.141.1586938805319; Wed, 15 Apr 2020 01:20:05 -0700 (PDT) Received: from google.com ([2a00:79e0:d:110:d6cc:2030:37c1:9964]) by smtp.gmail.com with ESMTPSA id f2sm22280970wro.59.2020.04.15.01.20.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2020 01:20:04 -0700 (PDT) Date: Wed, 15 Apr 2020 09:20:01 +0100 From: Quentin Perret To: Doug Anderson Cc: Ingo Molnar , Peter Zijlstra , juri.lelli@redhat.com, Vincent Guittot , dietmar.eggemann@arm.com, Steven Rostedt , bsegall@google.com, mgorman@suse.de, ctheegal@codeaurora.org, patrick.bellasi@matbug.net, valentin.schneider@arm.com, qais.yousef@arm.com, LKML , kernel-team@android.com Subject: Re: [PATCH] sched/core: Fix reset-on-fork from RT with uclamp Message-ID: <20200415082001.GA256573@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: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Doug, On Tuesday 14 Apr 2020 at 13:45:03 (-0700), Doug Anderson wrote: > Hi, > > On Tue, Apr 14, 2020 at 9:13 AM 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); > > - > > uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false); > > The local variable "clamp_value" doesn't have a lot of value anymore, > does it? (Pun intended). :) > Remove it? Right, but I figured the generated code should be similar, and 'uclamp_se_set(&p->uclamp_req[clamp_id], uclamp_none(clamp_id), false);' doesn't fit in 80 cols at this identation level, so I kept the local var. No strong opinion, though. Thanks, Quentin