In the production setup, we have two KVM servers. According to NTP, their clock 
corrections are:
server-a: -147.2 ppm
server-b: -142.1 ppm

NTP is running on the guest as well, and it's drift-rate matches
whichever server the guest is running on, after NTP has had time to
adjust.

The length of time that the guest freezes is exactly the time since the
last migration, times the NTP rate of the server it is on.

I did two migrations, one at 11h30, and another at 14h10, so 9600 seconds 
between migrations.
The freeze after the second migration was 1.369s (as reported by "ntpdate -q 
server-a", right after the migration).
This 9600 seconds, times the 142.1 ppm of the server it was on, would predict a 
freeze of 1.364 s.

I will set up a pair of machines with the qemu PPA later this week.

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https://bugs.launchpad.net/bugs/1297218

Title:
  guest hangs after live migration due to tsc jump

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