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 5DF8AEB64DC for ; Tue, 11 Jul 2023 03:25:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229458AbjGKDZ3 (ORCPT ); Mon, 10 Jul 2023 23:25:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229668AbjGKDZ1 (ORCPT ); Mon, 10 Jul 2023 23:25:27 -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 48E4FE3 for ; Mon, 10 Jul 2023 20:24:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689045885; 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=bj1nFMlX6IrlygC3UiCib90ggxtKBa1bC1e3kuNGIGw=; b=XycduuXzbU4b2u/W/ZhPT/bBWxCO+rNegHU7WufLyrkO+lzRQornCG1KaK78e8sUvHrmIy QlZH1d3nWm5BY3TF1HUVwzSW6vbLCDwDTyNi+i3vOwWnhNYfqpPs+NaOZnXTSaXEZCQsBO BLbRAZPV6bzvBAv60QRydhi3zPx1Cqc= 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-447-ZWqJQPhYO0Gqnk1uTT0naQ-1; Mon, 10 Jul 2023 23:24:39 -0400 X-MC-Unique: ZWqJQPhYO0Gqnk1uTT0naQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A17A01C07243; Tue, 11 Jul 2023 03:24:38 +0000 (UTC) Received: from [10.22.18.171] (unknown [10.22.18.171]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6DDEF40C206F; Tue, 11 Jul 2023 03:24:37 +0000 (UTC) Message-ID: <82aeb5aa-7d69-78dd-bb26-60a51dc8a839@redhat.com> Date: Mon, 10 Jul 2023 23:24:37 -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: [PATCH v4 8/9] cgroup/cpuset: Documentation update for partition 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 , Mrunal Patel , Ryan Phillips , Brent Rowsell , Peter Hunt , Phil Auld References: <20230627143508.1576882-1-longman@redhat.com> <20230627143508.1576882-9-longman@redhat.com> <6d5aee58-f558-868c-76e0-0b58f8332110@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 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 7/10/23 21:07, Tejun Heo wrote: > Hello, > > On Mon, Jul 10, 2023 at 08:53:18PM -0400, Waiman Long wrote: >> For local partition, it doesn't make sense to have a cpust.cpus.exclusive >> that is not the same as cpuset.cpus as it artificially reduce the set of >> CPUs that can be used in a partition. In the case of a remote partition, the > Yeah, I was wondering about local partitions. "Automatic but can be > overridden" behavior becomes confusing if it's difficult for the user to > easily tell which part is automatic when. I wonder whether it'd be better to > make the condition static - e.g. for a partition cgroup, cpus.exclusive > always contains all bits in cpus no matter what value is written to it. Or, > if we separate out cpus.exclusive and cpus.exclusive.effective, no matter > what cpus.exclusive is set, a partition root's cpus.exclusive.effective > always includes all bits in cpus.effective. With no offline CPUs, cpus.effective should be the same as cpus.exclusive.effective for a valid partition root. Here cpus.exclusive.effective is a bit different from cpus.effective as it can contain offline cpus. It also mean that adding cpus.exclusive.effective can be redundant. As said before, I try to avoid adding new cpuset control file unless absolutely necessary. I now have a slight different proposal. Once manually set, I can keep cpuset.cpus.exclusive invariant. I do need to do a bit more work when enabling a partition root to find out the effective set of exclusive CPUs to be used or make the partition invalid if no exclusive CPU is available. I still want to do a initial check when setting cpuset.cpus.exclusive to make sure that the value is at least valid at the beginning. Do you think this is an acceptable compromise? Thanks, Longman