Re: [PULL 00/18] migration queue

[Daniel P . Berrangé]

On Mon, Mar 14, 2022 at 05:15:57PM +0000, Peter Maydell wrote:
> On Mon, 14 Mar 2022 at 17:07, Daniel P. Berrangé <berrange@redhat.com> wrote:
> > So the test harness is waiting for a reply to 'query-migrate'.
> >
> > This should be fast unless QEMU has hung in the main event
> > loop servicing monitor commands, or stopped.
> 
> I was kind of loose with the terminology -- I don't remember whether
> it was actually hung in the sense of stopped entirely, or just
> "sat in a loop waiting for a migration state that never arrives".
> I'll try to look more closely if I can catch it in the act again.

Ah yes, if it is just forever migrating, that would match the
stack traces shown from the QEMUs. 

> One thing that makes this bug investigation trickier, incidentally,
> is that the migration-test code seems to depend on userfaultfd.
> That means you can't run it under 'rr'.

Yeah, we also can't turn on the tracing for a live QEMU since the
monitor connection is already in use. Kinda need to have a second
monitor instance present, that we can connect to for debugging
the migration state.

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|