From: Tejun Heo <tj@kernel.org>
To: Paul Menage <paul@paulmenage.org>
Cc: rjw@sisk.pl, lizf@cn.fujitsu.com,
linux-pm@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
containers@lists.linux-foundation.org,
Balbir Singh <bsingharora@gmail.com>,
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
James Morris <jmorris@namei.org>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 4/6] cgroup: don't use subsys->can_attach_task() or ->attach_task()
Date: Thu, 25 Aug 2011 11:12:28 +0200 [thread overview]
Message-ID: <20110825091228.GF3286@htj.dyndns.org> (raw)
In-Reply-To: <CALdu-PCc2RzedXubReF9huamL6W+5qGCfXNNvqS2yUk3QTHRng@mail.gmail.com>
Hello, Paul.
On Thu, Aug 25, 2011 at 02:07:35AM -0700, Paul Menage wrote:
> Doesn't the other part of this patch set, that avoids calling the
> *attach() methods for tasks that aren't moving, eliminate the need for
> the usage of skip_cgrp here (and elsewhere)? When do we actually need
> to pass a non-NULL skip_cgrp to cgroup_taskset_for_each()?
If any task is moving ->*attach() should be called. Whether the @tset
passed in should contain tasks which aren't changing cgroups is
debatable. The operation is guaranteed to be for an entire thread
group and it makes sense to make at least the leader always available
even if it's not moving. Given that the operation is defined to be
per-thread-group, I think it's better to pass in the whole thread
group with an easy way to skip the ones which aren't moving. For
example, memcg seems to need to find the mm->owner and it's possible
that the mm->owner might not be changing cgroups.
Thanks.
--
tejun
next prev parent reply other threads:[~2011-08-25 9:12 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-23 22:19 [PATCHSET] cgroup: introduce cgroup_taskset and consolidate subsys methods Tejun Heo
2011-08-23 22:19 ` [PATCH 1/6] cgroup: subsys->attach_task() should be called after migration Tejun Heo
2011-08-24 0:32 ` Frederic Weisbecker
2011-08-24 1:31 ` Li Zefan
2011-08-23 22:19 ` [PATCH 2/6] cgroup: improve old cgroup handling in cgroup_attach_proc() Tejun Heo
2011-08-25 8:51 ` Paul Menage
2011-08-25 9:03 ` Tejun Heo
2011-08-25 9:42 ` Paul Menage
2011-08-25 9:44 ` Tejun Heo
2011-08-23 22:19 ` [PATCH 3/6] cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach() Tejun Heo
2011-08-25 0:39 ` KAMEZAWA Hiroyuki
2011-08-25 8:20 ` Tejun Heo
2011-08-25 8:21 ` KAMEZAWA Hiroyuki
2011-08-25 8:40 ` Tejun Heo
2011-08-25 8:37 ` KAMEZAWA Hiroyuki
2011-08-25 9:14 ` Paul Menage
2011-08-25 9:20 ` Tejun Heo
2011-08-25 9:32 ` Paul Menage
2011-08-25 9:32 ` Paul Menage
2011-08-23 22:19 ` [PATCH 4/6] cgroup: don't use subsys->can_attach_task() or ->attach_task() Tejun Heo
2011-08-24 1:57 ` Matt Helsley
2011-08-24 7:54 ` Tejun Heo
2011-08-25 9:07 ` Paul Menage
2011-08-25 9:12 ` Tejun Heo [this message]
2011-08-23 22:19 ` [PATCH 5/6] cgroup, cpuset: don't use ss->pre_attach() Tejun Heo
2011-08-25 8:53 ` Paul Menage
2011-08-25 9:06 ` Tejun Heo
2011-08-23 22:20 ` [PATCH 6/6] cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() Tejun Heo
2011-08-25 9:45 ` Paul Menage
2011-08-24 1:14 ` [PATCHSET] cgroup: introduce cgroup_taskset and consolidate subsys methods Frederic Weisbecker
2011-08-24 7:49 ` Tejun Heo
2011-08-24 13:53 ` Frederic Weisbecker
2011-08-25 22:43 [PATCHSET] cgroup: introduce cgroup_taskset and consolidate subsys methods, take#2 Tejun Heo
2011-08-25 22:43 ` [PATCH 4/6] cgroup: don't use subsys->can_attach_task() or ->attach_task() Tejun Heo
2011-08-26 4:18 ` KAMEZAWA Hiroyuki
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