Re: [PATCH 00/10] cgroups: Task counter subsystem v6

[Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Tue, Dec 13, 2011 at 12:49:18PM -0800, Tejun Heo wrote:
> Hello,
> 
> On Tue, Dec 13, 2011 at 08:06:46PM +0100, Frederic Weisbecker wrote:
> > On Tue, Dec 13, 2011 at 07:58:48AM -0800, Tejun Heo wrote:
> > > Can you please rebase the patchset on top of cgroup/for-3.3?
> > 
> > Sure. But please note its fate is still under discussion. Whether
> > we want it upstream is still a running debate. But I certainly
> > need to rebase against your tree.
> 
> I see.
> 
> > > I primarily like the idea of being able to track process usage w/ cgroup
> > > and enforce limits on it but hope that it could somehow integrate w/
> > > cgroup freezer.  ie. trigger freezer if it goes over limit and let the
> > > userland tool / administrator deal with the frozen cgroup.  I'm
> > > planning on extending cgroup freezer such that it supports recursive
> > > freezing and killing of frozen tasks.  If we can fit task counters
> > > into that, we'll have general method of handling problematic cgroups -
> > > freeze, notify userland and let it deal with it.
> > 
> > Hmm, so you suggest a kernel trigger that freeze the cgroup when the
> > task limit is reached?
> 
> Yeah, something like that.  I'm not really sure about how it would
> actually work tho.
> 
> > What about rather implementing register_event() for the tasks.usage such
> > that the user can be notified using eventfd when the limit is reached.
> > Then it would be up to the user to decide to freeze or any other thing.
> > Sounds like a more generic solution.
> 
> Maybe, the problem would be how to ensure that the userland manager
> can respond fast enough (whatever that means...).

Yeah that's part of the goal of the task counter: limit the spreading
of the forkbomb soon enough such that the machine stays responsive and
the admin can react accordingly.