Re: [PATCHv3 8/8] cgroup: Add documentation for cgroup namespaces

From: Tejun Heo
Date: Wed Feb 11 2015 - 00:10:39 EST


Hello,

On Wed, Feb 11, 2015 at 05:29:42AM +0100, Serge E. Hallyn wrote:
> > There shouldn't be a "freezer" cgroup. The processes are categorized
> > according to their logical structure and controllers are applied to
> > the hierarchy as necessary.
>
> But there can well be cgroups for which only freezer is enabled. If
> I'm wrong about that, then I am suffering a fundamental misunderstanding.

Ah, sure, I was mostly arguing semantics. It's just weird to call it
"freezer" cgroup.

> > The semantics is that the parent enables distribution of its given
> > type of resource by enabling the controller in its subtree_control.
> > This scoping isn't necessary for freezer and I'm debating whether to
> > enable controllers which don't need granularity control to be enabled
> > unconditionally. Right now, I'm leaning against it mostly for
> > consistency.
>
> Yeah, IIUC (i.e. freezer would always be enabled?) that would be
> even-more-confusing.

Right, freezer is kinda weird tho. Its feature can almost be
considered a utility feature of cgroups core rather than a separate
controller. That said, it's most likely that it'll remain in its
current form although how it blocks tasks should definitely be
reimplemented.

Thanks.

--
tejun
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