[Openstack-operators] Puzzling issue: Unacceptable CPU info: CPU doesn't have compatibility

David Medberry openstack at medberry.net
Fri Jul 17 12:58:46 UTC 2015


HI Daniel,

Yep found that all out.

Now I'm struggling through the NUMA mismatch. NUMA as there are two cpus.
The old CPU was a 10 core 20 thread thus 40 "cpus", {0-9,20-29} and then
{10-19,30-39} on the other cell. The new CPU is a 12 core 24 thread.
Apparently even in kilo, this results in a mismatch if I'm running a 2 VCPU
guest and trying to migrate from new to old. I suspect I have to disable
NUMA somehow (filter, etc) but it is entirely non-obvious. And of course
I'm doing this again in OpenStack nova (not direct libvirt) so I'm going to
do a bit more research and then file a new bug. This also may be fixed in
Kilo but I"m not finding it (and it may be fixed in Liberty already and
just need a backport.)

My apologies for not following up to the list once I found the Kilo
solution to the original problem.

On Fri, Jul 17, 2015 at 6:10 AM, Daniel P. Berrange <berrange at redhat.com>
wrote:

> On Fri, Jul 17, 2015 at 01:07:56PM +0100, Daniel P. Berrange wrote:
> > On Thu, Jul 09, 2015 at 12:00:15PM -0600, David Medberry wrote:
> > > Hi,
> > >
> > > When trying to live-migrate between two distinct CPUs, I kind of expect
> > > there to be issues. Which is why openstack supports the
> "cpu_mode=custom",
> > > "cpu_model=MODELNAME" flags for libvirt.
> > >
> > > When I set those to some Lowest Common Denominator (and restart
> > > everything), I still git the issue. I've set both systems to
> SandyBridge
> > > and tested as well as Conroe. The actual CPUs are Ivy Bridge and
> Haswell
> > > (newer than SandyBridge and supersets thereof.)
> > >
> > > The Older->Newer migration works fine (even without setting a
> cpu_model)
> > > but the newer to older never works.
> > >
> > > Specfics:
> > > OpenStack Juno.2
> > > LibVirt: 1.2.2
> > >
> > > Older: model name : Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz (Ivy
> Bridge)
> > > Newer: model name : Intel(R) Xeon(R) CPU E5-2650 v3 @ 2.30GHz (Haswell)
> > >
> > > Daniel, Operators: Any ideas?
> >
> > In versions of Nova prior to Liberty, nova did an incorrect CPU model
> > comparison. It checks the source *host* CPU model against the dest
> > host CPU model, instead of checking the *guest* CPU model against the
> > dest host CPU model.
> >
> > This is fixed in Liberty, provided you have the cpu_mode=custom and
> > cpu_modelk=MODELNAME parameters set. Unfortunately the fix will only
> > work for guests that are launched under Liberty codebase as it needed
> > a database addition. So if you have existing running guests from Juno
> > those need restarting after upgrade.
>
> Sigh,  s/Liberty/Kilo/ in everything I wrote here
>
> Regards,
> Daniel
> --
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> :|
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