From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 0FE0E7D09D for ; Tue, 29 May 2018 06:27:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754542AbeE2G1J (ORCPT ); Tue, 29 May 2018 02:27:09 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:37971 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754200AbeE2G1I (ORCPT ); Tue, 29 May 2018 02:27:08 -0400 Received: by mail-wr0-f193.google.com with SMTP id 94-v6so23401528wrf.5 for ; Mon, 28 May 2018 23:27:07 -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=pKQ0hWI53KrPZTdEO/GXkZdpZrlhv7u5lX8uymEeEZQ=; b=VhazMS0FumxTpI+hyqKuGz9/ed4LAoFbJhDhzXGDNB2BoJjirbYKefYlDucRhcmFmY 9SE21XEH75NbNqQanutzn3lvS34kgCCfl5drKTIzi7Dsyl3RRvpEU2t5s7Yf9YhuiGT6 d3Dkb4yMIrP5bNpRWV6yUsU48qU5404cvlwS612ro+IH04H2GV+r5A3Q2A1XRtjkQTgj TKxvaCblZnvISF8LDwyRSTv3g9iYZc67PMHL4sjVC3QINpOXIZq1r4skrH2AI1N3ECeS HcHgq46kxUmmGxlbopNAuhYPdV0rb731gIS2+AzBV7y3kIOoMfGrPCxZtArV01ybAUZN uOow== X-Gm-Message-State: ALKqPwdAUJk9ae171ENnSbCdfS6WQ3H9PQiHFnAiQWbeKOKBFNXXkEZ+ 7PSWf3VyPDUom9aJaNyzsJi68A== X-Google-Smtp-Source: AB8JxZqEEzHaHnod2JM3KX1lOHPPMTcaTeCJQZJ9IuVejwQfggExSejpoP9z1ydAmUUYUzuKUnzjdw== X-Received: by 2002:adf:c08a:: with SMTP id d10-v6mr11251296wrf.268.1527575226983; Mon, 28 May 2018 23:27:06 -0700 (PDT) Received: from localhost.localdomain ([151.15.207.242]) by smtp.gmail.com with ESMTPSA id 12-v6sm19457318wmn.27.2018.05.28.23.27.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 28 May 2018 23:27:06 -0700 (PDT) Date: Tue, 29 May 2018 08:27:03 +0200 From: Juri Lelli To: Waiman Long Cc: Tejun Heo , Li Zefan , Johannes Weiner , Peter Zijlstra , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith , torvalds@linux-foundation.org, Roman Gushchin Subject: Re: [PATCH v8 4/6] cpuset: Make generate_sched_domains() recognize isolated_cpus Message-ID: <20180529062703.GA8985@localhost.localdomain> References: <1526590545-3350-1-git-send-email-longman@redhat.com> <1526590545-3350-5-git-send-email-longman@redhat.com> <20180524102837.GA3948@localhost.localdomain> <45d70c88-e9f5-716a-ee9a-33dc111159cc@redhat.com> <8e610b98-970c-a309-5821-fc8e6aca892f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8e610b98-970c-a309-5821-fc8e6aca892f@redhat.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 28/05/18 21:24, Waiman Long wrote: > On 05/28/2018 09:12 PM, Waiman Long wrote: > > On 05/24/2018 06:28 AM, Juri Lelli wrote: > >> On 17/05/18 16:55, Waiman Long wrote: > >> > >> [...] > >> > >>> @@ -849,7 +860,12 @@ static void rebuild_sched_domains_locked(void) > >>> * passing doms with offlined cpu to partition_sched_domains(). > >>> * Anyways, hotplug work item will rebuild sched domains. > >>> */ > >>> - if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) > >>> + if (!top_cpuset.isolation_count && > >>> + !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) > >>> + goto out; > >>> + > >>> + if (top_cpuset.isolation_count && > >>> + !cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask)) > >>> goto out; > >> Do we cover the case in which hotplug removed one of the isolated cpus > >> from cpu_active_mask? > > Yes, you are right. That is the remnant of my original patch that allows > > only one isolated_cpus at root. Thanks for spotting that. > > I am sorry. I would like to take it back my previous comment. The code > above looks for inconsistency in the state of the effective_cpus mask to > find out if it is racing with a hotplug event. If it is, we can skip the > domain generation as the hotplug event will do that too. The checks are > still valid with the current patchset. So I don't think we need to make > any change here. Yes, these checks are valid, but don't we also need to check for hotplug races w.r.t. isolated CPUs (of some other sub domain)? -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html