Re: [libvirt] cgroup cpuset limited by default?

On Tue, Apr 17, 2012 at 11:09:33AM +0530, Srivatsa S. Bhat wrote: > On 04/16/2012 09:43 PM, Daniel P. Berrange wrote: > >> On Mon, Apr 16, 2012 at 06:00:22PM +0200, Marc-André Lureau wrote: >>> Hi >>> >>> On Mon, Apr 16, 2012 at 2:32 PM, Srivatsa S. Bhat >>> <srivatsa.bhat(a)linux.vnet.ibm.com&gt; wrote: >>>> On 04/16/2012 05:34 PM, Marc-André Lureau wrote: >>>> Did you happen to perform a suspend/resume or a hibernation/restore >>>> on your computer? (Or did you do CPU hotplug manually?) >>>> >>>> If yes, you might be seeing the problem reported at: >>>> https://bugzilla.redhat.com/show_bug.cgi?id=714271 >>> >>> yep, thank you very much, that seems to be the reason > > > Thanks for the confirmation. The script below might work as a > temporary workaround. > >> >> This problem has existed for ages now. I wonder if there's a way we get get >> a userspace workaround implemented. >> >> IIRC, pm-utils has the ability to run arbitrary shell scripts upon >> restore from suspend/hibernate. We could put a temp hack in libvirt >> which resets the CPU affinity in the top level libvirt cgroup. That >> would at least make new VMs start with good affinity. To deal with >> existing running VMs, we would need to record existing affinity >> before suspend & re-store it fully afterwards which is more complicated >> > > > I don't think that would be all that complicated.. Below is a script > that should do the trick, for all cases, including existing running VMs. > > This script is not at all specific to libvirt by the way (as the problem > itself is not at all libvirt specific). It saves the cpuset configuration > before suspend and restores it after resume, for all cpusets (not only > the ones controlled by libvirt). Of course, it hooks onto the pm-utils > mechanism, as you mentioned. Thanks for taking the time to write this. I have opened a BZ against systemd to see if they are willing to ship this script as a standard workaround for the kernel bug, since they are responsible for mounting the cpuset cgroups in Fedora 16 and later https://bugzilla.redhat.com/show_bug.cgi?id=813228