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

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

On Sat, Oct 29, 2011 at 11:38:25AM +0200, Glauber Costa wrote:
> On Sat, Oct 29, 2011 at 1:30 AM, Andrew Morton
> <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> wrote:
> > On Tue, 25 Oct 2011 13:06:35 -0700
> > Tim Hockin <thockin-Rl2oBbRerpQdnm+yROfE0A@public.gmane.org> wrote:
> >
> >> On Tue, Oct 4, 2011 at 3:01 PM, Andrew Morton <akpm00-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >> > On Mon, __3 Oct 2011 21:07:02 +0200
> >> > Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >> >
> >> >> Hi Andrew,
> >> >>
> >> >> This contains minor changes, mostly documentation and changelog
> >> >> updates, off-case build fix, and a code optimization in
> >> >> res_counter_common_ancestor().
> >> >
> >> > I'd normally duck a patch series like this when we're at -rc8 and ask
> >> > for it to be resent late in -rc1. __But I was feeling frisky so I
> >> > grabbed this lot for a bit of testing and will sit on it until -rc1.
> >> >
> >> > I'm still not convinced that the kernel has a burning need for a "task
> >> > counter subsystem". __Someone convince me that we should merge this!
> >>
> >> We have real (accidental) DoS situations which happen because we don't
> >> have this.  It usually takes the form of some library no re-joining
> >> threads.  We end up deploying a few apps linked against this library,
> >> and suddenly we're in trouble on a machine.  Except, this being
> >> Google, we're in trouble on a lot of machines.
> >
> > This is a bit foggy.  I think you mean that machines are experiencing
> > accidental forkbombs?
> >
> >> There may be other ways to cobble this sort of safety together, but
> >> they are less appealing for various reasons.  cgroups are how we
> >> control groups of related pids.
> >>
> 
> In the end of the day, all cgroups are just a group of tasks. So I don't really
> get the need to have a cgroup to control the number of tasks in the system.
> 
> Why don't we just allow all cgroups to have a limit on the number of
> tasks it can hold?

Not sure what you mean. You would prefer to have this as a core feature in
cgroups rather than a subsystem?