[lxc-devel] [PATCH RFC] cgroups: use cgfs when possible

[Serge Hallyn]

Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
> Because it is easier on the host.  When creating many containers,
> reducing the load on the cgroup manager can greatly reduce the
> cpu usage.  Until now, we have used cgmanager whenever we could.
> Now we use cgfs when we can, and switch to cgmanager if needed.
> 
> At cgroup init, we first check whether we can use cgfs.  If we
> can, we use it rather than cgmanager.  This means that cgfs needs
> to actually check whether it can be used.  We do this by making
> sure that every needed hierarchy has a writeable mountpoint.
> 
> We also now need to have cgfs call cgmanager's mount_setup(), as
> any nested use of cgroups may well need to be using cgmanager.
> 
> This requires a patch to the lxcfs mount hook to avoid failure
> on mkdir.  (A better fix would be nice, but this suffices to make
> things work)
> 
> This also gets rid of the cgroup_driver enum, which wasn't
> actually used anywhere.
> 
> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>

Self-nack.  Excuse the noise.