From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751748AbeCTUMb convert rfc822-to-8bit (ORCPT ); Tue, 20 Mar 2018 16:12:31 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:41776 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751343AbeCTUM2 (ORCPT ); Tue, 20 Mar 2018 16:12:28 -0400 Subject: Re: [PATCH v5 2/2] cpuset: Add cpuset.flags control knob to v2 From: Waiman Long To: Tejun Heo Cc: 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, efault@gmx.de, torvalds@linux-foundation.org, Roman Gushchin References: <1521148842-15486-1-git-send-email-longman@redhat.com> <1521148842-15486-3-git-send-email-longman@redhat.com> <20180319162654.GR2943022@devbig577.frc2.facebook.com> <8e553b7e-cab6-1b5d-9110-cc5770ae16c4@redhat.com> Organization: Red Hat Message-ID: Date: Tue, 20 Mar 2018 16:12:25 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <8e553b7e-cab6-1b5d-9110-cc5770ae16c4@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19/2018 12:33 PM, Waiman Long wrote: > On 03/19/2018 12:26 PM, Tejun Heo wrote: >> Hello, Waiman. >> >> On Thu, Mar 15, 2018 at 05:20:42PM -0400, Waiman Long wrote: >>> + The currently supported flag is: >>> + >>> + sched_load_balance >>> + When it is not set, there will be no load balancing >>> + among CPUs on this cpuset. Tasks will stay in the >>> + CPUs they are running on and will not be moved to >>> + other CPUs. >>> + >>> + When it is set, tasks within this cpuset will be >>> + load-balanced by the kernel scheduler. Tasks will be >>> + moved from CPUs with high load to other CPUs within >>> + the same cpuset with less load periodically. >> Hmm... looks like this is something which can be decided by the cgroup >> itself and should be made delegatable. Given that different flags >> might need different delegation settings and the precedence of >> memory.oom_group, I think it'd be better to make the flags separate >> bool files - ie. cpuset.sched_load_balance which contains 0/1 and >> marked delegatable. >> >> Thanks. >> > Sure. Will do that. After some thought, I am planning to impose the following additional constraints on how sched_load_balance works in v2. 1) sched_load_balance will be made hierarchical, the child will inherit the flag from its parent. 2) cpu_exclusive will be implicitly associated with sched_load_balance. IOW, sched_load_balance => !cpu_exclusive, and !sched_load_balance => cpu_exclusive. 3) sched_load_balance cannot be 1 on a child if it is 0 on the parent. With these changes, sched_load_balance will have to be set by the parent and so will not be delegatable. Please let me know your thought on that. Cheers, Longman