Re: [PATCH v2] memcg: first step towards hierarchical controller

Michal Hocko
2012-09-06T12:06:23Z

On Wed 05-09-12 13:12:38, Tejun Heo wrote:
> Hello, Michal.
>
> On Wed, Sep 05, 2012 at 04:49:42PM +0200, Michal Hocko wrote:
> > Can we settle on the following 3 steps?
> > 1) warn about "flat" hierarchies (give it X releases) - I will push it
> > to as many Suse code streams as possible (hope other distributions
> > could do the same)
>
> I think I'm just gonna trigger WARN from cgroup core if anyone tries
> to create hierarchy with a controller which doesn't support full
> hierarchy. WARN_ON_ONCE() at first and then WARN_ON() on each
> creation later on.

How do you find out that a controller is not fully hierarchical? Memory
controller can be both.

> > 2) flip the default on the root cgroup & warn when somebody tries to
> > change it to 0 (give it another X releases) that the knob will be
> > removed
> > 3) remove the knob and the whole nonsese
> > 4) revert 3 if somebody really objects
>
> If we can get to 3, I don't think 4 would be a problem.

Agreed.
--
Michal Hocko
SUSE Labs