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Re: [Xen-devel] clock drift in Xen 4.0.0

To: James Harper <james.harper@xxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] clock drift in Xen 4.0.0
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 25 May 2010 08:58:39 +0100
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On 25/05/2010 08:01, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:

>> Are you running NTP? 100ppm drift isn't unbelievable without external
>> synchronisation.
> That's 7 minutes in front of the Dom0 that it's sitting on. The Dom0
> runs ntp. Another DomU on the same system is ahead by a similar amount
> (9 minutes over 74 days). I thought that with independent_wallclock=0
> that they should stay in step.
> I actually just noticed that I'm running 4.0.0-rc6, not 4.0.0 proper...
> d'oh. I think I should probably update before thinking about it much
> more.

It probably depends on your dom0 and domU kernels also. Have they both been
observed to behave 'properly' before? In particular I'm not sure pv_ops
behaves same as ealrier kernels.

 -- Keir

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