From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933749AbdEXSTQ (ORCPT ); Wed, 24 May 2017 14:19:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40256 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933130AbdEXSTO (ORCPT ); Wed, 24 May 2017 14:19:14 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 899AA7F6AA Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=longman@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 899AA7F6AA Subject: Re: [RFC PATCH v2 12/17] cgroup: Remove cgroup v2 no internal process constraint To: Tejun Heo References: <1494855256-12558-1-git-send-email-longman@redhat.com> <1494855256-12558-13-git-send-email-longman@redhat.com> <20170519203824.GC15279@wtj.duckdns.org> <93a69664-4ba6-9ee8-e4ea-ce76b6682c77@redhat.com> <20170524170527.GH24798@htj.duckdns.org> Cc: Li Zefan , Johannes Weiner , Peter Zijlstra , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, efault@gmx.de From: Waiman Long Organization: Red Hat Message-ID: <97996c22-57c3-aea4-c06a-5a57e8520f36@redhat.com> Date: Wed, 24 May 2017 14:19:12 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170524170527.GH24798@htj.duckdns.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 24 May 2017 18:19:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/24/2017 01:05 PM, Tejun Heo wrote: > Hello, > > On Mon, May 22, 2017 at 12:56:08PM -0400, Waiman Long wrote: >> All controllers can use the special sub-directory if userland chooses to >> do so. The problem that I am trying to address in this patch is to allow >> more natural hierarchy that reflect a certain purpose, like the task >> classification done by systemd. Restricting tasks only to leaf nodes >> makes the hierarchy unnatural and probably difficult to manage. > I see but how is this different from userland just creating the leaf > cgroup? I'm not sure what this actually enables in terms of what can > be achieved with cgroup. I suppose we can argue that this is more > convenient but I'd like to keep the interface orthogonal as much as > reasonably possible. > > Thanks. > I am just thinking that it is a bit more natural with the concept of the special resource domain sub-directory. You are right that the same effect can be achieved by proper placement of tasks and enabling of controllers. A (cpu,memory) [T1] - B(cpu,memory) [T2] \ cgroups.resource_domain (memory) A (cpu,memory) - B(cpu,memory) [T2] \ C (memory) [T1] With respect to the tasks T1 and T2, the above 2 configurations are the same. I am OK to drop this patch. However, I still think the current no-internal process constraint is too restricting. I will suggest either 1. Allow internal processes and document the way to avoid internal process competition as shown above from the userland, or 2. Mark only certain controllers as not allowing internal processes when they are enabled. What do you think about this? Cheers, Longman