Comment 47 for bug 1392176

Quoting Martin Pitt (<email address hidden>):
> Serge Hallyn [2015-04-17 17:49 -0000]:
> > Cpusets are not *required* for lxc. Perhaps we should in fact default
> > to only providing name=systemd, devices and freezer cgroups for users?
> > We'd want to very widely advertise how to enable other cgroups.
>
> Right, I mostly understood it so that we need to create all those
> controllers in the host that the container workload can *potentially*
> use all these cgroups as well, not that they are inherently required.
>
> > Currently lxc would fail this way, but we could teach it to ignore
> > inability to create cgroups which aren't required. (This isn't as
> > simple as it seems, since using the keyword "all" for controllers
> > would no longer work, but it's doable)
>
> "all" could still try to join all controllers, but ignore the ones it
> doesn't have permissions for?
>
> Maybe also (1) a new weak version of "all" which implements that
> behaviour, or (2) a new strong version which will fail if it cannot
> join any controller. TBH I don't know which way around would break
> backwards compat less: (1) requires changing all existing container
> configs on upgrade once we stop putting the user session into all
> controllers, and (2) might break existing container workloads which
> actually expect the dropped controllers.
>
> My gut feeling is that (2) is the better option.

I agree. (the same will be needed for create)