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From Josh Harshman <>
Subject Hyper-V clock on KVM node - CLOUDSTACK-8978
Date Sat, 24 Oct 2015 00:15:07 GMT
Just looking for some feedback on this idea for an improvement.

Currently, for any windows guest OS, we set RTC for the clock source. This seems to contribute
to clock-drift issues leading to BSODs on Windows Server 2008 R2 Guests.

I believe a possible improvement would be to set Windows guests to use the hyper-v clock.
To do this we will need CloudStack to generate the appropriate Libvirt XML which would look
somewhat like the following:

<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='8191'/>
<clock ...>
<timer name='hypervclock' present='yes'/>

I believe the following code snippet from could be a starting
place to implement this.

if (vmTO.getOs().startsWith("Windows")) {
clock.setTimer("rtc", "catchup", null);

Let me know what you all think about this change.
Is there a better place / way to implement this?

Josh Harshman

Cloud Engineer

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Fax: (866) 565-4578
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