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=-5.6 required=5.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, T_DKIM_INVALID 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 C49E27E278 for ; Wed, 2 May 2018 14:08:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751144AbeEBOIv (ORCPT ); Wed, 2 May 2018 10:08:51 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38896 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751109AbeEBOIu (ORCPT ); Wed, 2 May 2018 10:08:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=C1H3Ob2QKGUSolnCS2yNEqJK5IQKKBmRUzbgjMwvlNw=; b=a/f2hcrpeagigO9lON0xl/Pi4 wDm8Vxl2wOFDb+3NXq1EwIx1NfPmHxKkwKHf+Tr5EQ9qB0+0H8j3i1BTqB6qSsyrs0eYFgyqHi7Dq oy1QtNuhtkk1/lMmwtodf8xPXtF+rpWCdcybYv6rv4ZWJEFuDIJVKzfoReOr/BGeRp1rvhSKGzIQX 0OQELoMUewIWtkilLd7vQdipjbm6vl+rcDhek1eg5Pf3BGOXJGlQmHsdnznyREDCoRgqMNuhU57Gq WD24Ihg3pFwg2vASg9iGvbBAXnBMzRH5b77AtNuOrScUoWugfhJS0dw3JZQOqu3iBWSB0c5BviuP5 E2Y16qdEA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fDsQw-0003vx-GC; Wed, 02 May 2018 14:08:38 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D9C9E2029FA14; Wed, 2 May 2018 16:08:35 +0200 (CEST) Date: Wed, 2 May 2018 16:08:35 +0200 From: Peter Zijlstra To: Waiman Long Cc: Tejun Heo , Li Zefan , Johannes Weiner , 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 , Juri Lelli Subject: Re: [PATCH v7 3/5] cpuset: Add a root-only cpus.isolated v2 control file Message-ID: <20180502140835.GK12180@hirez.programming.kicks-ass.net> References: <1524145624-23655-1-git-send-email-longman@redhat.com> <1524145624-23655-4-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1524145624-23655-4-git-send-email-longman@redhat.com> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Apr 19, 2018 at 09:47:02AM -0400, Waiman Long wrote: > diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt > index c970bd7..8d89dc2 100644 > --- a/Documentation/cgroup-v2.txt > +++ b/Documentation/cgroup-v2.txt > @@ -1484,6 +1484,31 @@ Cpuset Interface Files > a subset of "cpuset.cpus". Its value will be affected by CPU > hotplug events. > > + cpuset.cpus.isolated > + A read-write multiple values file which exists on root cgroup > + only. > + > + It lists the CPUs that have been withdrawn from the root cgroup > + for load balancing. These CPUs can still be allocated to child > + cpusets with load balancing enabled, if necessary. > + > + If a child cpuset contains only an exclusive set of CPUs that are > + a subset of the isolated CPUs and with load balancing enabled, > + these CPUs will be load balanced on a separate root domain from > + the one in the root cgroup. > + > + Just putting the CPUs into "cpuset.cpus.isolated" will be > + enough to disable load balancing on those CPUs as long as they > + do not appear in a child cpuset with load balancing enabled. > + Fine-grained control of cpu isolation can also be done by > + putting these isolated CPUs into child cpusets with load > + balancing disabled. > + > + The "cpuset.cpus.isolated" should be set up before child > + cpusets are created. Once child cpusets are present, changes > + to "cpuset.cpus.isolated" will not be allowed if the CPUs that > + change their states are in any of the child cpusets. > + So I see why you did this, but it is _really_ ugly and breaks the container invariant. Ideally we'd make the root group less special, not more special. -- 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