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=-10.9 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,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 A8A5DC433E0 for ; Thu, 21 Jan 2021 06:30:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6361222248 for ; Thu, 21 Jan 2021 06:30:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726662AbhAUGas (ORCPT ); Thu, 21 Jan 2021 01:30:48 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:20332 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726669AbhAUG35 (ORCPT ); Thu, 21 Jan 2021 01:29:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611210505; 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: in-reply-to:in-reply-to:references:references; bh=A/Nv6GHCQlumzPaFQAXiaHrHMfj3/YhSy2fwNasMTmw=; b=M1J+EPI7mHjM6cRLfs87FiBA+Uwj1FKJMZum8tfZohO4H4u+htuk3PahQg4ohO50P6B4Tj yIFuWkNiACFRf/058nwGEpgh4r1qdbhY7A61tb0HYdOOtEtoY+0xniMvt1+2/nMupczz52 pPQOg+l6DPsmaa0vdadLpp0gN67njXE= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-157-bL4ljgdHNC-2KRyhqNKf9g-1; Thu, 21 Jan 2021 01:28:23 -0500 X-MC-Unique: bL4ljgdHNC-2KRyhqNKf9g-1 Received: by mail-ed1-f71.google.com with SMTP id u17so582754edi.18 for ; Wed, 20 Jan 2021 22:28:23 -0800 (PST) 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=A/Nv6GHCQlumzPaFQAXiaHrHMfj3/YhSy2fwNasMTmw=; b=gp1PAJeKEa/L39GHoFnSdR0+mMclhHJRUqvUSXIB3XjTpQ22MY982Y2bRMNIRwIbdO 3b/wDyGQ5X0B4O/yZGj9TxgoPyAqmvmh9DO2cPUduwFJNw59nlzaaT5qCspq1S7JBZOH fD1TqSNYEDin69wjWY4SUPxojDNvtMQpuGDp1ks5iX0eRzFMiPmczjQB0SLuBPzSQQe8 2EdQI0BRtQ6ZkURh/vmlW4t1PGETIUv+oqrW+tyZyH758rPd5jvCkHjU6fPQuhjAiFL3 HcBlM6aq04v5zAkNCOglhzJ7NqkTnxeoNQEXmi5Bz15tspQ6H6Rp4X8leHh4wG3r4l8L hYqQ== X-Gm-Message-State: AOAM531aBJhQIIBY3PeQhFOkiT3fZXqrtqyddn1nCFOA/yUSbzsrb2L6 bUCWcZ0osA36NfVyLzXk6wJ+4OLfcaB1IsN1rsyM7eIIKyDnOrrkgmk/gEgfXv2q3wn6RLC1v7i U64jhV5mqAPpsV2XGOMn2TSvJ X-Received: by 2002:a17:906:aec1:: with SMTP id me1mr8805629ejb.114.1611210502430; Wed, 20 Jan 2021 22:28:22 -0800 (PST) X-Google-Smtp-Source: ABdhPJwgvwiFmsXss14kPoPcd+j0USA1s+mP/BikoSlDkv7eXGzd0l3lQAShgpK3XYQfPcSWmez7cw== X-Received: by 2002:a17:906:aec1:: with SMTP id me1mr8805619ejb.114.1611210502205; Wed, 20 Jan 2021 22:28:22 -0800 (PST) Received: from localhost.localdomain ([151.29.110.43]) by smtp.gmail.com with ESMTPSA id d8sm2231050edm.75.2021.01.20.22.28.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Jan 2021 22:28:21 -0800 (PST) Date: Thu, 21 Jan 2021 07:28:19 +0100 From: Juri Lelli To: Dietmar Eggemann Cc: Ingo Molnar , Peter Zijlstra , Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org, Vincent Guittot , Steven Rostedt , Quentin Perret , Valentin Schneider Subject: Re: [PATCH] sched/deadline: Reduce rq lock contention in dl_add_task_root_domain() Message-ID: <20210121062819.GH10569@localhost.localdomain> References: <20210119083542.19856-1-dietmar.eggemann@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210119083542.19856-1-dietmar.eggemann@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 19/01/21 09:35, 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 Looks good to me, thanks! Acked-by: Juri Lelli Best, Juri