Re: [RFD][PATCH] memcg: Move Usage at Task Move

["Paul Menage" <menage@google.com>]

On Wed, Jun 11, 2008 at 1:27 AM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
> Sorry. try another sentense..
>
> I think cgroup itself is designed to be able to be used without middleware.

True, but it shouldn't be hostile to middleware, since I think that
automated use will be much more common. (And certainly if you count
the number of servers :-) )

> IOW, whether using middleware or not is the matter of users not of developpers.
> There will be a system that system admin controlles all and move tasks by hand.
> ex)...personal notebooks etc..
>

You think so? I think that at the very least users will be using tools
based around config scripts, rule engines and libcgroup, if not a
persistent daemon.

>> If the common mode for middleware starting a new cgroup is fork() /
>> move / exec() then after the fork(), the child will be sharing pages
>> with the main daemon process. So the move will pull all the daemon's
>> memory into the new cgroup
>>
> My patch (this patch) just moves Private Anon page to new cgroup. (of mapcount=1)

OK, well that makes it more reasonable regarding the above problem.
But I can still see problems if, say, a single thread moves into a new
cgroup, you move the entire memory. Perhaps you should only do so if
the mm->owner changes task?

Paul

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