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 B0C6DC77B73 for ; Fri, 14 Apr 2023 17:43:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229636AbjDNRnI (ORCPT ); Fri, 14 Apr 2023 13:43:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229847AbjDNRm5 (ORCPT ); Fri, 14 Apr 2023 13:42:57 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71DF1AF0A for ; Fri, 14 Apr 2023 10:42:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681494122; 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=YShER/83lVY8rjvwP0DGbgGKGuajPMgVY3SrTBvwiQg=; b=WxB1NOUGhTG4Sx8ChuCv7tGybtEfiWDBLLDuQ6XZ0L2zEzThvBfNKwXzc8hENS0vKZDtEG AlYhMv5X36qsSFUgcOvEfwzjj9kMCvqKC7od7td5xJRNgvv5OHIG6G9k3M2XhKJ7tKIHIZ FcVNfcxUgDY1m5pJbDA9oLUei0T+tuk= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-47-S2cIwDP4MLWRPH72GQb-OQ-1; Fri, 14 Apr 2023 13:41:20 -0400 X-MC-Unique: S2cIwDP4MLWRPH72GQb-OQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C2CFE3C184EE; Fri, 14 Apr 2023 17:38:49 +0000 (UTC) Received: from [10.22.18.140] (unknown [10.22.18.140]) by smtp.corp.redhat.com (Postfix) with ESMTP id 32B53492B01; Fri, 14 Apr 2023 17:38:49 +0000 (UTC) Message-ID: <60ec12dc-943c-b8f0-8b6f-97c5d332144c@redhat.com> Date: Fri, 14 Apr 2023 13:38:49 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [RFC PATCH 0/5] cgroup/cpuset: A new "isolcpus" paritition Content-Language: en-US To: Tejun Heo Cc: Zefan Li , Johannes Weiner , Jonathan Corbet , Shuah Khan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Juri Lelli , Valentin Schneider , Frederic Weisbecker References: <1b8d9128-d076-7d37-767d-11d6af314662@redhat.com> <9862da55-5f41-24c3-f3bb-4045ccf24b2e@redhat.com> <226cb2da-e800-6531-4e57-cbf991022477@redhat.com> From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 4/14/23 13:34, Tejun Heo wrote: > On Fri, Apr 14, 2023 at 01:29:25PM -0400, Waiman Long wrote: >> On 4/14/23 12:54, Tejun Heo wrote: >>> On Thu, Apr 13, 2023 at 09:22:19PM -0400, Waiman Long wrote: >>>> I now have a slightly different idea of how to do that. We already have an >>>> internal cpumask for partitioning - subparts_cpus. I am thinking about >>>> exposing it as cpuset.cpus.reserve. The current way of creating >>>> subpartitions will be called automatic reservation and require a direct >>>> parent/child partition relationship. But as soon as a user write anything to >>>> it, it will break automatic reservation and require manual reservation going >>>> forward. >>>> >>>> In that way, we can keep the old behavior, but also support new use cases. I >>>> am going to work on that. >>> I'm not sure I fully understand the proposed behavior but it does sound more >>> quirky. >> The idea is to use the existing subparts_cpus for cpu reservation instead of >> adding a new cpumask for that purpose. The current way of partition creation >> does cpus reservation (setting subparts_cpus) automatically with the >> constraint that the parent of a partition must be a partition root itself. >> One way to relax this constraint is to allow a new manual reservation mode >> where users can set reserve cpus manually and distribute them down the >> hierarchy before activating a partition to use those cpus. >> >> Now the question is how to enable this new manual reservation mode. One way >> to do it is to enable it whenever the new cpuset.cpus.reserve file is >> modified. Alternatively, we may enable it by a cgroupfs mount option or a >> boot command line option. > It'd probably be best if we can keep the behavior within cgroupfs if > possible. Would you mind writing up the documentation section describing the > behavior beforehand? I think things would be clearer if we look at it from > the interface documentation side. Sure, will do that. I need some time and so it will be early next week. Cheers, Longman