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From: Tejun Heo <tj@kernel.org>
To: Mike Galbraith <efault@gmx.de>
Cc: Waiman Long <longman@redhat.com>, Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	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
Subject: Re: [RFC PATCH v2 12/17] cgroup: Remove cgroup v2 no internal process constraint
Date: Wed, 24 May 2017 13:01:40 -0400	[thread overview]
Message-ID: <20170524170140.GG24798@htj.duckdns.org> (raw)
In-Reply-To: <1495246207.7442.2.camel@gmx.de>

Hello, Mike.

On Sat, May 20, 2017 at 04:10:07AM +0200, Mike Galbraith wrote:
> On Fri, 2017-05-19 at 16:38 -0400, Tejun Heo wrote:
> > Hello, Waiman.
> > 
> > On Mon, May 15, 2017 at 09:34:11AM -0400, Waiman Long wrote:
> > > The rationale behind the cgroup v2 no internal process constraint is
> > > to avoid resouorce competition between internal processes and child
> > > cgroups. However, not all controllers have problem with internal
> > > process competiton. Enforcing this rule may lead to unnatural process
> > > hierarchy and unneeded levels for those controllers.
> > 
> > This isn't necessarily something we can determine by looking at the
> > current state of controllers.  It's true that some controllers - pid
> > and perf - inherently only care about membership of each task but at
> > the same time neither really suffers from the constraint either.  CPU
> > which is the problematic one here...
> 
> (+ cpuacct + cpuset)

Yeah, cpuacct and cpuset are in the same boat as perf.  cpuset is
completely so and we can move the tree walk to the reader side or
aggregate propagation for cpuacct as necessary.

Thanks.

-- 
tejun

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  reply	other threads:[~2017-05-24 17:01 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-15 13:33 [RFC PATCH v2 00/17] cgroup: Major changes to cgroup v2 core Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 01/17] cgroup: reorganize cgroup.procs / task write path Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 02/17] cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 03/17] cgroup: introduce cgroup->proc_cgrp and threaded css_set handling Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 04/17] cgroup: implement CSS_TASK_ITER_THREADED Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 05/17] cgroup: implement cgroup v2 thread support Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 06/17] cgroup: Fix reference counting bug in cgroup_procs_write() Waiman Long
2017-05-17 19:20   ` Tejun Heo
2017-05-15 13:34 ` [RFC PATCH v2 07/17] cgroup: Prevent kill_css() from being called more than once Waiman Long
2017-05-17 19:23   ` Tejun Heo
2017-05-17 20:24     ` Waiman Long
2017-05-17 21:34       ` Tejun Heo
2017-05-15 13:34 ` [RFC PATCH v2 08/17] cgroup: Move debug cgroup to its own file Waiman Long
2017-05-17 21:36   ` Tejun Heo
2017-05-18 15:29     ` Waiman Long
2017-05-18 15:52     ` Waiman Long
2017-05-19 19:21       ` Tejun Heo
2017-05-19 19:33         ` Waiman Long
2017-05-19 20:28           ` Tejun Heo
2017-05-15 13:34 ` [RFC PATCH v2 09/17] cgroup: Keep accurate count of tasks in each css_set Waiman Long
2017-05-17 21:40   ` Tejun Heo
2017-05-18 15:56     ` Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 10/17] cgroup: Make debug cgroup support v2 and thread mode Waiman Long
2017-05-17 21:43   ` Tejun Heo
2017-05-18 15:58     ` Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 11/17] cgroup: Implement new thread mode semantics Waiman Long
2017-05-17 21:47   ` Tejun Heo
2017-05-18 17:21     ` Waiman Long
2017-05-19 20:26   ` Tejun Heo
2017-05-19 20:58     ` Tejun Heo
2017-05-22 17:13     ` Waiman Long
2017-05-22 17:32       ` Waiman Long
2017-05-24 20:36       ` Tejun Heo
2017-05-24 21:17         ` Waiman Long
2017-05-24 21:27           ` Tejun Heo
2017-06-01 14:50             ` Tejun Heo
2017-06-01 15:10               ` Peter Zijlstra
2017-06-01 15:35                 ` Tejun Heo
2017-06-01 18:44                 ` Waiman Long
2017-06-01 18:47                   ` Tejun Heo
2017-06-01 19:27                     ` Waiman Long
2017-06-01 20:38                       ` Tejun Heo
2017-06-01 20:48                         ` Waiman Long
2017-06-01 20:52                           ` Tejun Heo
2017-06-01 21:12                             ` Waiman Long
2017-06-01 21:18                               ` Tejun Heo
2017-06-02 20:36                                 ` Waiman Long
2017-06-03 10:33                                   ` Tejun Heo
2017-06-01 19:55                   ` Waiman Long
2017-06-01 20:15                 ` Waiman Long
2017-06-01 18:41               ` Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 12/17] cgroup: Remove cgroup v2 no internal process constraint Waiman Long
2017-05-19 20:38   ` Tejun Heo
2017-05-20  2:10     ` Mike Galbraith
2017-05-24 17:01       ` Tejun Heo [this message]
2017-05-22 16:56     ` Waiman Long
2017-05-24 17:05       ` Tejun Heo
2017-05-24 18:09         ` Waiman Long
2017-05-24 18:19         ` Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 13/17] cgroup: Allow fine-grained controllers control in cgroup v2 Waiman Long
2017-05-19 20:55   ` Tejun Heo
2017-05-19 21:20     ` Waiman Long
2017-05-24 17:31       ` Tejun Heo
2017-05-24 17:49         ` Waiman Long
2017-05-24 17:56           ` Tejun Heo
2017-05-24 18:17             ` Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 14/17] cgroup: Enable printing of v2 controllers' cgroup hierarchy Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 15/17] sched: Misc preps for cgroup unified hierarchy interface Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 16/17] sched: Implement interface for cgroup unified hierarchy Waiman Long
2017-05-15 13:34 ` [RFC PATCH v2 17/17] sched: Make cpu/cpuacct threaded controllers Waiman Long

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