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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC170C25B50 for ; Fri, 20 Jan 2023 22:17:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229970AbjATWRu (ORCPT ); Fri, 20 Jan 2023 17:17:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229741AbjATWRs (ORCPT ); Fri, 20 Jan 2023 17:17:48 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C530A126C0 for ; Fri, 20 Jan 2023 14:17:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674253020; 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=PymHzUQySveMLAeF0IwXdw52bO+MwC9kbQnHrMu8WUY=; b=CW6Ozsn7//fTUgxjZQSr5IOxvgVYkfJdQ7448gAJZN/FAouMSRAZJ2Vf3oZlasD6qydlCk 5ppD7tIKWvAcuHBKJ3Kt+uoTmp3vR/5sFL1gis3uH8jgATu+OhZn98mCV5UhwWnsZh9S8X DqQTIpAVpXTDCU5ussFdjn7DkgIw39M= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-610-bKRJsAD2Mz-gc6apOXEULA-1; Fri, 20 Jan 2023 17:16:57 -0500 X-MC-Unique: bKRJsAD2Mz-gc6apOXEULA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DD91E185A78B; Fri, 20 Jan 2023 22:16:56 +0000 (UTC) Received: from [10.22.17.220] (unknown [10.22.17.220]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6CC49C15BAD; Fri, 20 Jan 2023 22:16:55 +0000 (UTC) Message-ID: Date: Fri, 20 Jan 2023 17:16:55 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v2] sched: cpuset: Don't rebuild sched domains on suspend-resume To: Qais Yousef , Peter Zijlstra , Ingo Molnar , Juri Lelli Cc: Steven Rostedt , tj@kernel.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it, bristot@redhat.com, mathieu.poirier@linaro.org, Dietmar Eggemann , cgroups@vger.kernel.org, Vincent Guittot , Wei Wang , Rick Yiu , Quentin Perret References: <20230120194822.962958-1-qyousef@layalina.io> Content-Language: en-US From: Waiman Long In-Reply-To: <20230120194822.962958-1-qyousef@layalina.io> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/20/23 14:48, Qais Yousef wrote: > Commit f9a25f776d78 ("cpusets: Rebuild root domain deadline accounting information") > enabled rebuilding sched domain on cpuset and hotplug operations to > correct deadline accounting. > > Rebuilding sched domain is a slow operation and we see 10+ ms delay on > suspend-resume because of that. > > Since nothing is expected to change on suspend-resume operation; skip > rebuilding the sched domains to regain the time lost. > > Debugged-by: Rick Yiu > Signed-off-by: Qais Yousef (Google) > --- > > Changes in v2: > > * Remove redundant check in update_tasks_root_domain() (Thanks Waiman) > > v1 link: > > https://lore.kernel.org/lkml/20221216233501.gh6m75e7s66dmjgo@airbuntu/ > > kernel/cgroup/cpuset.c | 3 +++ > kernel/sched/deadline.c | 3 +++ > 2 files changed, 6 insertions(+) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index a29c0b13706b..9a45f083459c 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -1088,6 +1088,9 @@ static void rebuild_root_domains(void) > lockdep_assert_cpus_held(); > lockdep_assert_held(&sched_domains_mutex); > > + if (cpuhp_tasks_frozen) > + return; > + > rcu_read_lock(); > > /* > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 0d97d54276cc..42c1143a3956 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -2575,6 +2575,9 @@ void dl_clear_root_domain(struct root_domain *rd) > { > unsigned long flags; > > + if (cpuhp_tasks_frozen) > + return; > + > raw_spin_lock_irqsave(&rd->dl_bw.lock, flags); > rd->dl_bw.total_bw = 0; > raw_spin_unlock_irqrestore(&rd->dl_bw.lock, flags); cpuhp_tasks_frozen is set when thaw_secondary_cpus() or freeze_secondary_cpus() is called. I don't know the exact suspend/resume calling sequences, will cpuhp_tasks_frozen be cleared at the end of resume sequence? Maybe we should make sure that rebuild_root_domain() is called at least once at the end of resume operation. Cheers, Longman