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

[KAMEZAWA Hiroyuki]

On Wed, 11 Jun 2008 01:48:20 -0700
"Paul Menage" <menage at google.com> wrote:

> On Wed, Jun 11, 2008 at 1:27 AM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu at 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.
> 
I believe some users will never use middlewares because of their special
usage of linux.



> >> 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?
> 

Thank you for pointing out. I'll add mm->owner check.

BTW, should we have a cgroup for SYSVIPC resource controller and devide it
from memory resource controller ?  I think that per-task on-demand usage
accounting is not suitable for shmem (and hugepage).
per-creater (caller of shmget()) accounting seems to be better for me.

Just a question:
What happens when a thread (not thread-group-leader) changes its ns by
ns-cgroup ? not-allowed ?


Thanks,
-Kame



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