[systemd-devel] [PATCH] cgroup-util: Add more well-known controller names

[Stéphane Graber]

On Mon, Dec 01, 2014 at 06:24:48AM +0100, Martin Pitt wrote:
> Hey Lennart,
> 
> Lennart Poettering [2014-12-01  0:44 +0100]:
> > > +        "hugetlb\0"
> > > +        "cpuset\0"
> > > +        "net_cls\0"
> > > +        "net_prio\0"
> > > +        "freezer\0"
> > > +        "perf_event\0";
> > 
> > In general we should be really careful about manipulating hierarchies
> > we don't know enough about, since some controllers actually have an
> > effect on a process even with no actual cgroup property changed from
> > the default ("cpu" is an obvious one, which breaks RT scheduling). 
> 
> I asked Stéphane (LXC upstream) about that some days/weeks ago, and he
> said that this issue was fixed upstream in the kernel. I have no
> further info about this, perhaps he can reply with some details?

Not so much fixed in the kernel as not a problem if you make sure you
kernel isn't built with CONFIG_RT_GROUP_SCHED enabled
(which we did for the Ubuntu kernels).

So obviously the real fix there is the unified hierarchy which by design
will give us what we want. Until then, having this be configurable so
that distros can choose to use the feature or not depending on the
features they care about should be a reasonable stop gap measure.

Or indeed as suggested, just do it as a distro patch.

> 
> > I figure before adding these controllers to the list systemd manages
> > we need to open the discussion with Tejun about the future of the
> > respective controllers...
> > 
> > I think it would be better to apply a patch of thee downstream if at
> > all, for now, if you need it now. 
> 
> Ack, that's ok.
> 
> Martin
> -- 
> Martin Pitt                        | http://www.piware.de
> Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)

-- 
Stéphane Graber
Ubuntu developer
http://www.canonical.com
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