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Re: [Xen-devel] Dom0 <> DomU clock sync

To: Sébastien RICCIO <sr@xxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Dom0 <> DomU clock sync
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 03 Sep 2007 15:17:30 +0100
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 3/9/07 15:07, "Sébastien RICCIO" <sr@xxxxxxxxxxxxxxx> wrote:

> Ntpd is not running in dom0. I am updating the dom0 time with ntpdate
> (crontab every hour).
> Should ntpd be running on dom0 ?

So long as ntpdate calls settimeofday(), this should be sufficient to update
Xen's notion of time too. It seems that isn't happening for some reason.

Do all guests (including dom0) have independent_wallclock equal to 0?

What kernel are you using in dom0 (e.g., vendor kernel?).

Ntpd in dom0 would be an interesting thing to try. That should cause dom0 to
periodically (every few minutes) push its time down to Xen to be picked up
by all domUs. But really ntpdate should be doing the right thing...

In our kernels it should be *impossible* for dom0 and domU time to diverge
when independent_wallclock is set to zero everywhere...

 -- Keir

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