Re: [libvirt] why doesn't libvirt let qemu autostart live-migrated VMs?

On 04/15/2014 02:28 AM, Daniel P. Berrange wrote: >On Mon, Apr 14, 2014 at 05:50:07PM -0600, Chris Friesen wrote: >>Hi, >> >>I've been digging through the libvirt code and something that struck >>me was that it appears that when using qemu libvirt will migrate the >>instance with autostart disabled, then sit on the source host >>periodically polling for migration completion, then once the host >>detects that migration is completed it will tell the destination to >>start up the VM. >> >>Why don't we let the destination autostart the VM once migration is >>complete? > >Libvirt has to have synchronization point on the target machine, so >that we can acquire any disk leases associated with the VM before >the CPUs are started. Where does that happen? I'm looking at libvirt/qemu, specifically this code path on the target: remoteDispatchDomainMigrateFinish3ParamsHelper remoteDispatchDomainMigrateFinish3Params virDomainMigrateFinish3Params qemuDomainMigrateFinish3Params qemuMigrationFinish qemuProcessStartCPUs qemuMonitorStartCPUs