[libvirt] [PATCH 1/2] qemu: Resolve issue with virsh schedinfo for non running domain

[Daniel P. Berrange]

On Thu, May 30, 2013 at 08:24:59AM -0400, John Ferlan wrote:
> Since commit '632f78ca' the 'virsh schedinfo <domain>' command returns:
> 
> Scheduler      : Unknown
> error: Requested operation is not valid: cgroup CPU controller is not mounted
> 
> Prior to that change a non running domain would return:
> 
> Scheduler      : posix
> cpu_shares     : 0
> vcpu_period    : 0
> vcpu_quota     : 0
> emulator_period: 0
> emulator_quota : 0
> 
> This change will result in the following:
> 
> Scheduler      : posix
> cpu_shares     : 0

Hmm, no this isn't right. The entire approach of this method to changing
the set of tunables reported, according to the state of cgroups is broken
by design.

We should always unconditionally report all 5 tunables whether running
or shutoff.

Then when starting a guest, we should report an error if the admin has
set a non-default  emulator_quota/emulator_period values and the
corresponding cgrpoups aren't available.

Likewise when changing tunables on a running guest, we should report
an error if the admin attempts to change the values of tunables that
are not currently supported.


Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|