From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eduardo Habkost <ehabkost@redhat.com>
Subject: Re: TSC deadline timer in guests vs. migration?
Date: Mon, 4 Jul 2016 16:07:10 -0300
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To: Paolo Bonzini <pbonzini@redhat.com>
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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.

I believe it can. Also: what about everything else the guest may
try to use the TSC for? (even without TSC deadline timer)

>>From a quick look at Linux code, it looks like the TSC
clocksource code is more strict (but the exact rules are hard to
follow), but it will still use the TSC in native_sched_clock().

What about kvmclock? Do we have a mechanism to trigger a re-read
of TSC frequency from the hypervisor?

-- 
Eduardo