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 508EBC433F5 for ; Wed, 4 May 2022 11:26:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231319AbiEDL3f (ORCPT ); Wed, 4 May 2022 07:29:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348719AbiEDL3b (ORCPT ); Wed, 4 May 2022 07:29:31 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2B3502A71C; Wed, 4 May 2022 04:25:55 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id BE45B210E0; Wed, 4 May 2022 11:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1651663553; h=from:from:reply-to: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=IHotc1tLxNFQnMsMhQ4/PAmmsXVX/ZrmEY2hoLkhoeY=; b=prmLabugZEs93348NyPI+Rk+PvbnW03y6T9MnWqgkElCaLaxD76fSofTgRaeDBgj+VsO+6 JJrL0pJY5taH3pcpCX3mOYmFXRH4wLu2FwI9+uFoFQy61iIBDOsN98iOmHbJLnWAaSemYH wBbOqgwKNBoCX7DWQOQHFbvaRdjwiaA= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 5E694132C4; Wed, 4 May 2022 11:25:53 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id GYZmFcFicmKxPgAAMHmgww (envelope-from ); Wed, 04 May 2022 11:25:53 +0000 Date: Wed, 4 May 2022 13:25:52 +0200 From: Michal =?iso-8859-1?Q?Koutn=FD?= To: Waiman Long Cc: Tejun Heo , Zefan Li , Johannes Weiner , Jonathan Corbet , Shuah Khan , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Roman Gushchin , Phil Auld , Peter Zijlstra , Juri Lelli , Frederic Weisbecker , Marcelo Tosatti Subject: Re: [PATCH v10 7/8] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Message-ID: <20220504112552.GA15266@blackbody.suse.cz> References: <20220503162149.1764245-1-longman@redhat.com> <20220503162149.1764245-8-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220503162149.1764245-8-longman@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello. On Tue, May 03, 2022 at 12:21:48PM -0400, Waiman Long wrote: > Documentation/admin-guide/cgroup-v2.rst | 145 +++++++++++++----------- > 1 file changed, 79 insertions(+), 66 deletions(-) A note across various lines -- it seems your new text accidentally mixes both spaces and tabs for indentation. > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 69d7a6983f78..94e1e3771830 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > [...] > + The value shown in "cpuset.cpus.effective" of a partition root is > + the CPUs that the parent partition root can dedicate to the new > + partition root. They are subtracted from "cpuset.cpus.effective" > + of the parent and may be different from "cpuset.cpus" I find this paragraph a bit hard to comprehend (I read it as it talks about three levels of cgroups (parent, child, grandparent). It is correct but I'd suggect following formulation (where I additionally simplifed it by talking about "available" cpus): > The value shown in "cpuset.cpus.effective" of a partition root is > the CPUs that the partition root can dedicate to a potential new child > partition root. The new child subtracts available CPUs from its parent > "cpuset.cpus.effective". > + For a partition root to become valid, the following conditions > + must be met. > + > + 1) The "cpuset.cpus" is exclusive, i.e. they are not shared by > + any of its siblings (exclusivity rule). > + 2) The parent cgroup is a valid partition root. > + 3) The "cpuset.cpus" is not empty and must contain at least > + one of the CPUs from parent's "cpuset.cpus", i.e. they overlap. > + 4) The "cpuset.cpus.effective" must be a subset of "cpuset.cpus" > + and cannot be empty unless there is no task associated with > + this partition. This sounds good to me. > + Care must be taken to change a valid partition root to "member" > + as all its child partitions, if present, will become invalid. This does not talk about recovering. Is it intentional? (I.e. to left implementation defined) Except the remarks above, I find the concepts described here good. I'll reply to implementation separately & later. Regards, Michal