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SubjectRe: [RFC] Shared page accounting for memory cgroup
* KAMEZAWA Hiroyuki <> [2010-01-06 16:12:11]:

> On Wed, 6 Jan 2010 12:31:50 +0530
> Balbir Singh <> wrote:
> > > No. If it takes long time, locking fork()/exit() for such long time is the bigger
> > > issue.
> > > I recommend you to add memacct subsystem to sum up RSS of all processes's RSS counting
> > > under a cgroup. Althoght it may add huge costs in page fault path but implementation
> > > will be very simple and will not hurt realtime ops.
> > > There will be no terrible race, I guess.
> > >
> >
> > But others hold that lock as well, simple thing like listing tasks and
> > moving tasks, etc. I expect the usage of shared to be in the same
> > range.
> >
> And piles up costs ? I think cgroup guys should pay attention to fork/exit
> costs more. Now, it gets slower and slower.
> In that point, I never like migrate-at-task-move work in cpuset and memcg.
> My 1st objection to this patch is this "shared" doesn't mean "shared between
> cgroup" but means "shared between processes".
> I think it's of no use and no help to users.

So what in your opinion would help end users? My concern is that as
we make progress with memcg, we account only for privately used pages
with no hint/data about the real usage (shared within or with other
cgroups). How do we decide if one cgroup is really heavy?

> And implementation is 2nd thing.

More details on your concern, please!


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