[systemd-devel] Fedora 25, cgroups V2 and systemd roadmap

[Lennart Poettering]

On Mon, 10.10.16 17:35, Daniel P. Berrange (berrange at redhat.com) wrote:

> > Before we can tell Docker/libvirt to port their stuff over I figure we
> > also need one more addition in the systemd API for this: next to
> > Delegate=yes|no (which we already have) we probably need to add
> > DelegateController= taking a list of all controllers to
> > delegate. Right now we delegate all controllers, but I figure that
> > should be configurable, since turning on a controller might have
> > effects people don't expect (in particular for the cpu hierarchy).
> 
> >From the libvirt POV, getting the CPU controller support merged is
> a blocking item, otherwise we have a major feature regression. We
> have a policy of not supporting code that is out of tree, as we don't
> like getting burnt when changes are inevitably made after it is finally
> accepted.

I still hope that Fedora can go the Facebook route, and just patch the
stuff in, and ignore the fight going on in the kernel community.

That said, note that we actually besides legacy and v2 cgroups mode we
actually support a hybrid mode: v2 for everything that the kernel
supports plus legacy for the crappy controllers that aren't yet up to
it (including "cpu").

Of course, this requires explicit support in the various delegation
services too, hence I'd much prefer if the main distros would just
apply the out-of-tree patch and we could go full-on v2...

Lennart

-- 
Lennart Poettering, Red Hat