Re: [PATCH v3 2/7] socket: initial cgroup code.

[Glauber Costa]

On 09/22/2011 12:09 PM, Balbir Singh wrote:
> On Thu, Sep 22, 2011 at 11:30 AM, Greg Thelen<gthelen@xxxxxxxxxx>  wrote:
> > On Wed, Sep 21, 2011 at 11:59 AM, Glauber Costa<glommer@xxxxxxxxxxxxx>  wrote:
> > > Right now I am working under the assumption that tasks are long lived inside
> > > the cgroup. Migration potentially introduces some nasty locking problems in
> > > the mem_schedule path.
> > >
> > > Also, unless I am missing something, the memcg already has the policy of
> > > not carrying charges around, probably because of this very same complexity.
> > >
> > > True that at least it won't EBUSY you... But I think this is at least a way
> > > to guarantee that the cgroup under our nose won't disappear in the middle of
> > > our allocations.
> >
> > Here's the memcg user page behavior using the same pattern:
> >
> > 1. user page P is allocate by task T in memcg M1
> > 2. T is moved to memcg M2.  The P charge is left behind still charged
> > to M1 if memory.move_charge_at_immigrate=0; or the charge is moved to
> > M2 if memory.move_charge_at_immigrate=1.
> > 3. rmdir M1 will try to reclaim P (if P was left in M1).  If unable to
> > reclaim, then P is recharged to parent(M1).
>
> We also have some magic in page_referenced() to remove pages
> referenced from different containers. What we do is try not to
> penalize a cgroup if another cgroup is referencing this page and the
> page under consideration is being reclaimed from the cgroup that
> touched it.
>
> Balbir Singh
humm... Then we need to keep pointers to: 1) Which allocations comes 
from each socket, and 2) Which sockets comes from each task. 2 is pretty 
easy, 1 may get expensive. I will investigate it now.

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