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=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,NICE_REPLY_A,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 80C1CC433E6 for ; Wed, 20 Jan 2021 07:54:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 55F2123158 for ; Wed, 20 Jan 2021 07:54:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729757AbhATHyj (ORCPT ); Wed, 20 Jan 2021 02:54:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:37722 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729859AbhATHyA (ORCPT ); Wed, 20 Jan 2021 02:54:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611129150; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Obl4hVrOzCc41rjsElBS4MYaL9yxoBBFhMxhO9jt+S8=; b=jP/Flsznm9CHuSglHJwW7dWybwG4TA5PBNPz5eJSsbx9r0Ej5pshP4ekx5LlCuZpr954hv bK2Oklv1zLxMOlFK1sDoxzV3LTvLtIx2VnHGcDyslctVEw8zFVnyzjH7j73euzbjMYZ/Mi HqymEXblhOqc7hUoWWpVRdUdQAXz7ZM= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-441-av2J8OphPQCh3wQus-J-Lg-1; Wed, 20 Jan 2021 02:52:28 -0500 X-MC-Unique: av2J8OphPQCh3wQus-J-Lg-1 Received: by mail-ed1-f69.google.com with SMTP id ck25so6806456edb.16 for ; Tue, 19 Jan 2021 23:52:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Obl4hVrOzCc41rjsElBS4MYaL9yxoBBFhMxhO9jt+S8=; b=ZxcSnUg/Q1qtkdG9Q3auTmTPA3Rnm9EyJP6SSlrAl1ZJyfwJP3hzObq9md96rgLL3h edqgo9YZWd4j1T+ECZ7SpeD2Nsoj07qBbeY+jvg9y6Kakcf9Cev2LdR40qrG57MJeeTm n4zgjO+HDiZpQ6J56TcodqGGC3Way1+smHN6XKW0D+iY+BYavOs2o2rR6JZ+7b34rJTC 8Qj4vdhUrQCtrzhbdtAM8y0zxUth4+lA7iDiPnX8B16P2qMPW4XshlvkQFvwzKDTsQXa X1zbVvQRc0256JN7BQSw6f897gJ4EnyV4DIUXWAmhNKGsCRzOViHFHq/wLW+pQkSnEuI N5lQ== X-Gm-Message-State: AOAM532wITafr4glRsvSJbEzrueVMAcPJFtYuUpW2sQnDhg1cWOmCbZh 6fT3QMIWmkh7k1+CXmb5syQuoM7TYlifi43jwzqd3ke990Lls+P9so4RL8mygtNmGdLGa8KyPYN X/X6Mfj9bMpM4X0+jOIarTh+n X-Received: by 2002:a17:906:e43:: with SMTP id q3mr5114732eji.493.1611129147632; Tue, 19 Jan 2021 23:52:27 -0800 (PST) X-Google-Smtp-Source: ABdhPJxN/M3Bq/jSmASqFCtK9VpGoLfwDFJt5BXL9BQV3K/IZ56ZdYAFmWapUXhBnMQ4GxIT6O0rLg== X-Received: by 2002:a17:906:e43:: with SMTP id q3mr5114723eji.493.1611129147459; Tue, 19 Jan 2021 23:52:27 -0800 (PST) Received: from x1.bristot.me (host-79-46-192-171.retail.telecomitalia.it. [79.46.192.171]) by smtp.gmail.com with ESMTPSA id p89sm639178edb.61.2021.01.19.23.52.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Jan 2021 23:52:26 -0800 (PST) Subject: Re: [PATCH] sched/deadline: Reduce rq lock contention in dl_add_task_root_domain() To: Dietmar Eggemann , Ingo Molnar , Peter Zijlstra , Juri Lelli Cc: linux-kernel@vger.kernel.org, Vincent Guittot , Steven Rostedt , Quentin Perret , Valentin Schneider References: <20210119083542.19856-1-dietmar.eggemann@arm.com> From: Daniel Bristot de Oliveira Message-ID: Date: Wed, 20 Jan 2021 08:52:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210119083542.19856-1-dietmar.eggemann@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/19/21 9:35 AM, Dietmar Eggemann wrote: > dl_add_task_root_domain() is called during sched domain rebuild: > > rebuild_sched_domains_locked() > partition_and_rebuild_sched_domains() > rebuild_root_domains() > for all top_cpuset descendants: > update_tasks_root_domain() > for all tasks of cpuset: > dl_add_task_root_domain() > > Change it so that only the task pi lock is taken to check if the task > has a SCHED_DEADLINE (DL) policy. In case that p is a DL task take the > rq lock as well to be able to safely de-reference root domain's DL > bandwidth structure. > > Most of the tasks will have another policy (namely SCHED_NORMAL) and > can now bail without taking the rq lock. > > One thing to note here: Even in case that there aren't any DL user > tasks, a slow frequency switching system with cpufreq gov schedutil has > a DL task (sugov) per frequency domain running which participates in DL > bandwidth management. > > Reviewed-by: Quentin Perret > Signed-off-by: Dietmar Eggemann Reviewed-by: Daniel Bristot de Oliveira Thanks! -- Daniel