[drbd-mc] LCMC feature request to fix clock skew in Windows guests.

Rasto Levrinc rasto.levrinc at gmail.com
Fri Mar 22 09:55:55 CET 2013


On Thu, Dec 13, 2012 at 2:37 PM, Caspar Smit <c.smit at truebit.nl> wrote:
> Hi Rasto,
>

> I noticed that in Windows 7 and Windows 2008 based VM's the clock of the
> guest falls behind the host's clock.
> Under heavy load of the VM this can result in 4 minutes behind during a 15
> minutes period, quite a lot.
>
> To fix this I found a combination of needed options in Libvirt:
>
> <clock offset='localtime'>
>   <timer name='rtc' tickpolicy='catchup'/>
>   <timer name='hpet' present='no'/>
> </clock>

Hi Caspar,

it seams that these settings should be ok for both Windows and Linux.
I've made "offset" configurable in the LCMC.

<clock offset="utc/localtime">
	<timer name="rtc" tickpolicy="catchup" />
	<timer name="pit" tickpolicy="delay" />
	<timer name="hpet" present="no" />
</clock>

If there's demand to make these timers configurable I'll gladly add it.

Thanks,
Rasto

>
> Default LCMC creates:
> <clock offset='utc'/>
>
> offset=localtime is best to use for Windows guests (according to the
> qemu-kvm manpage).
>
> It would be really nice if these libvirt options were configurable in LCMC.
>
> Kind regards,
>
> Caspar Smit

-- 
Dipl.-Ing. Rastislav Levrinc
rasto.levrinc at gmail.com
Linux Cluster Management Console
http://lcmc.sf.net/


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