From owner-freebsd-xen@FreeBSD.ORG  Mon May 30 10:27:47 2011
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Date: Mon, 30 May 2011 10:27:37 +0000 (UTC)
From: Janne Snabb <snabb@epipe.com>
To: Alex <other@ahhyes.net>
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Cc: freebsd-xen@freebsd.org
Subject: Re: Clock drift issues
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On Mon, 30 May 2011, Alex wrote:

> The clock is Sync'd though, it should *stay* correct, right? So there is a
> bug?

My experience is also that the clock is not stable on FreeBSD 8.X
guest on Xen and KVM HVM. It is unusable as a ntp server for other
hosts and I need to run ntpd to prevent the guest clock from drifting
and jumping.

Some times I get syslog messages about the time going backwards,
which is probably related:

calcru: runtime went backwards from 41668 usec to 35093 usec for pid 96767 (bash)

I have not tried this with the CURRENT kernel (which has new and
configurable event timer infrastructure by mav@).

(Linux guests are fine for running ntp server within Xen & KVM.)

--
Janne Snabb / EPIPE Communications
snabb@epipe.com - http://epipe.com/