On Tue, Jul 05, 2016 at 09:51:41AM -0300, Marcelo Tosatti wrote: > On Mon, Jul 04, 2016 at 04:45:06PM -0300, Eduardo Habkost wrote: > > On Mon, Jul 04, 2016 at 04:30:08PM -0300, Marcelo Tosatti wrote: > > > On Mon, Jul 04, 2016 at 01:01:42PM +0200, Paolo Bonzini wrote: > > > > Can bad things happen if a guest using the TSC deadline timer is > > > > migrated? The guest doesn't re-calibrate the TSC after migration, and > > > > the TSC frequency can and will change unless your data center is > > > > perfectly homogeneous. > > > > > > It can fire earlier if the destination runs at a higher frequency. > > > It will fire past the configured time if the destination runs at a slower frequency. > > > > > > Suppose the first case is worse. > > > > > > Should convert the expiration time to nanoseconds i suppose, and then > > > convert back on the destination. > > > > This won't make any difference if the guest sets up a new timer > > after migration (but using the old TSC frequency), will it? > > It does, because the timer setup traps to the host, where you can > convert it to the proper value: To convert it to the proper value, you need to know what's the TSC frequency the guest is assuming. How would you do that? -- Eduardo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
