From mboxrd@z Thu Jan  1 00:00:00 1970
From: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Subject: Re: [PATCH] cgroups: add task along with its threads in one shot
	inside	cgroup
Date: Thu, 18 Dec 2008 09:51:52 +0800
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To: Gowrishankar M <gowrishankar.m-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>, Sukadev <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Balbir <balbir-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Eric <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>, Dave <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
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Gowrishankar M wrote:
> From: Gowrishankar M <gomuthuk-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
> 
> In current model, task by task we populate cgroup.
> Incase of multi-threaded task, it becomes difficult
> as we should first know about list of threads created
> and add them one by one in cgroup.
> 

It was proposed to add 'procs' control file to do so long ago, but there
is a big issue, that there is no way to do it atomically, i.e you may
success to move some threads but fail for others.

You can get some information here:
	https://lists.linux-foundation.org/pipermail/containers/2008-July/011747.html

> In below patch, when a thread group leader is scanned,
> belonging threads are also moved along with it, while
> populating cgroup tasks.