Re: [RFD] cgroup: about multiple hierarchies

From: Lennart Poettering
Date: Mon Mar 12 2012 - 18:31:23 EST


On Mon, 12.03.12 15:28, Tejun Heo (tj@xxxxxxxxxx) wrote:

>
> Hey,
>
> On Mon, Mar 12, 2012 at 11:22:18PM +0100, Peter Zijlstra wrote:
> > On Mon, 2012-03-12 at 15:10 -0700, Tejun Heo wrote:
> > >
> > > * How to map controllers which aren't aware of full hierarchy is still
> > > an open question but I'm still standing by one active node on any
> > > root-to-leaf path w/ root group serving as the special rest group.
> >
> > What does this mean?
>
> Let's say we have a tree like the following.
>
> root
> / | \
> G1 G2 G3
> / \
> G31 G32
>
> So, for cgroups which don't support full hierarchy, it'll be viewed as
> either,
>
> root
> / | \
> G1 G2 G3
>
> or
>
> root
> / | | \
> G1 G2 G31 G32
>
> With root being treated specially, probably as just being a equal
> group as other groups, I'm not fully determined about that yet.

Note that at least systemd places all services by default beneath a
single "super" group (/system/), hence the first suggestion would make
little sense for us. The second suggestion would be fine however.

Lennart

--
Lennart Poettering - Red Hat, Inc.
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