On 11/14/19 10:30 AM, Michael Weiser wrote: > Hello, > > I expect this pops up every couple of months and apologise if indeed it > does. But I couldn't find a discussion specific to virt-manager and so > it goes: > > When working with snapshots, guests will have outdated date and time > upon resume. Although the (virtual) hardware clock seems to get updated > upon resume, it can take quite a long time until the guest OS resyncs > its current time from either that or via NTP. I've seen workarounds > employing hwclock --hctosys in once-a-minute cron jobs or very > aggressive NTP client configs. > > Now I have come across an agent based solution in Nova[1] and ported it > PoC-style to virt-manager. It works very well for me. > > Would this be something that could be considered for inclusion? > Or is there another mechanism that should already take care of this and > just doesn't work in my case? > Yes it's definitely worth fixing, we are overdue for it in fact. There's a virt-manager bug about it, it doesn't have much more info though: https://bugzilla.redhat.com/show_bug.cgi?id=1222069 > [1] https://github.com/openstack/nova/commit/414df1e56ea9df700756a1732125e06c5d97d792. > > PoC code: > > --- virt-manager/virtManager/object/domain.py.orig 2019-10-31 17:35:04.829950245 +0100 > +++ virt-manager/virtManager/object/domain.py 2019-10-31 18:19:39.834899951 +0100 > @@ -1276,7 +1276,28 @@ > > @vmmLibvirtObject.lifecycle_action > def startup(self): > + sync_time = self.has_managed_save() > self._backend.create() > + if sync_time: > + dry = 1 > + while dry < 5: > + t = time.time() > + seconds = int(t) > + nseconds = int((t - seconds) * 10 ** 9) > + try: > + self._backend.setTime(time = {'seconds': seconds, 'nseconds': nseconds}) > + except libvirt.libvirtError as e: > + code = e.get_error_code() > + if code == libvirt.VIR_ERR_AGENT_UNRESPONSIVE: > + log.debug('Failed to set time: QEMU agent unresponsive') > + elif code == libvirt.VIR_ERR_NO_SUPPORT: > + log.debug('Failed to set time: not supported') > + elif code == libvirt.VIR_ERR_ARGUMENT_UNSUPPORTED: > + log.debug('Failed to set time: agent not configured') > + else: > + log.warning('Failed to set time: %s', e) > + > + dry += 1 > I like the idea of using nova's code, that's a good starting point. Add a comment in the code that that this is inspired by nova code, with a link to that commit you mentioned, it's a good reference. Everything under sync_time can be moved to its own function, def _set_time(self), so we can easily reuse it from other code paths like snapshot restore and possibly resume from pause. The different log levels aren't interesting for virt-manager, you can just do: except Exception as e: log.debug("Failed to set time: %s", e) With those changes it will be commitable IMO. After that, some ideas are: * Only run the API for qemu and test drivers, they are the only ones that support it. This will save spamming logs with error output * For qemu, only run the API if the VM has the qemu guest agent in the XML. * Wire it up for snapshot restore, and possibly after unpause (need to confirm it's desired there) * Maybe dispatch the whole thing in its old thread, so it doesn't appear in the UI like the VM start process is blocked by the time API completing. I can help with the extra bits but I'm happy to provide guidance if you'd like to work on them too. Thanks, Cole _______________________________________________ virt-tools-list mailing list virt-tools-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/virt-tools-list
