Re: [Xen-users] Clock (time) issue

[Steven Timm <timm@xxxxxxxx>]

Mark, are your domU's 32-bit or 64-bit, likewise with dom0?
We have seen the domU clock on a 32-bit instance jump forward
by 40-80 minutes for no good reason and stay stuck there until
the outside world catches up (and any time set commands fail).
But never saw dom0 clock jump.

Steve


On Mon, 4 Oct 2010, Mark Adams wrote:

> Hi All,
>
> Im running Xen 4.0.1-rc6 Debian squeeze with pvops 2.6.32-21 kernel.
> Today I noticed (when kerberos to the domain controllers stopped
> working..) that the clock was 50 minutes out in dom0 -- This caused the
> HVM windows domain controllers to have the wrong time.
>
> I'm not sure if this is a kernel issue or a xen issue, but the only
> thing related is I can see the following in the kernel log:
>
> Oct  2 18:50:33 havhost1 kernel: [623480.977748] Clocksource tsc unstable 
> (delta = -2999660303788 ns)
>
> But I also see in the dmesg log that xen is using it's own clock.
>
> [    7.676563] Switching to clocksource xen
>
> I can't identify anything else in the logs to indicate when the time
> might have changed. I have a few other dom0 at the same level that
> haven't decided to change the time.
>
> Can anyone confirm whether xen controls the time or the kernel? Also
> when I corrected the time in dom0 it was still wrong in HVM domU -- How
> long does it take for this to propogate? (I rebooted the VM's to correct
> it immediately).
>
> Any other pointers on how to ensure stability of clocks from dom0 to
> domU HVM hosts (and pv for that matter..) would be appreciated.
>
> Cheers,
> Mark
>
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> http://lists.xensource.com/xen-users
--
------------------------------------------------------------------
Steven C. Timm, Ph.D  (630) 840-8525
timm@xxxxxxxx  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Assistant Group Leader.

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