Xen users - Sep 2007 - Time went backwards in domU after migration

Hello gurus,

I have two physical xen hosts and when I migrate a domU from one host to 
another, I get many of this error from domU kernel:

clocksource/0: Time went backwards: delta=-3536123661 shadow=686019823475
offset=281887188

Sometimes domU time stalls and network stops working, but other times it
gets working again.

The two hosts are using different platform timer source:

root@xen1test:~# xm dmesg|grep -i timer
(XEN) Platform timer is 14.318MHz HPET

root@xen2:~# xm dmesg|grep -i timer
(XEN) Platform timer is 1.193MHz PIT

Both hosts use Ubuntu Gutsy (latest as of today) packaged version of Xen
3.1.0, Linux 2.6.22 (on both dom0 and domU).

Dom0s are working flawlessly.

Thanks in advance,
Takeshi

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I changed the BIOS setting so both hosts use 1.193MHz PIT,
but it didn''t get fixed. 

Takeshi Sone wrote:
> Hello gurus,
> 
> I have two physical xen hosts and when I migrate a domU from one host to 
> another, I get many of this error from domU kernel:
> 
> clocksource/0: Time went backwards: delta=-3536123661 shadow=686019823475
offset=281887188
> 
> Sometimes domU time stalls and network stops working, but other times it
> gets working again.
> 
> The two hosts are using different platform timer source:
> 
> root@xen1test:~# xm dmesg|grep -i timer
> (XEN) Platform timer is 14.318MHz HPET
> 
> root@xen2:~# xm dmesg|grep -i timer
> (XEN) Platform timer is 1.193MHz PIT
> 
> Both hosts use Ubuntu Gutsy (latest as of today) packaged version of Xen
> 3.1.0, Linux 2.6.22 (on both dom0 and domU).
> 
> Dom0s are working flawlessly.
> 
> Thanks in advance,
> Takeshi
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users

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Enabling HPET on both hosts didn''t help either.

Also I found that the same error occurs when I just save domU, reboot 
dom0, and restore domU.


Takeshi Sone wrote:
> I changed the BIOS setting so both hosts use 1.193MHz PIT,
> but it didn''t get fixed.
> Takeshi Sone wrote:
>> Hello gurus,
>>
>> I have two physical xen hosts and when I migrate a domU from one host 
>> to another, I get many of this error from domU kernel:
>>
>> clocksource/0: Time went backwards: delta=-3536123661 
>> shadow=686019823475 offset=281887188
>>
>> Sometimes domU time stalls and network stops working, but other times
it
>> gets working again.
>>
>> The two hosts are using different platform timer source:
>>
>> root@xen1test:~# xm dmesg|grep -i timer
>> (XEN) Platform timer is 14.318MHz HPET
>>
>> root@xen2:~# xm dmesg|grep -i timer
>> (XEN) Platform timer is 1.193MHz PIT
>>
>> Both hosts use Ubuntu Gutsy (latest as of today) packaged version of
Xen
>> 3.1.0, Linux 2.6.22 (on both dom0 and domU).
>>
>> Dom0s are working flawlessly.
>>
>> Thanks in advance,
>> Takeshi
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@lists.xensource.com
>> http://lists.xensource.com/xen-users
> 
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users

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Xen-users@lists.xensource.com
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Hi,

I can reproduce this too - Gutsy versions of Xen 3.1.0 with the Gutsy
2.6.22 kernel on dom0 and domU.

It sometimes migrates ok for me, but mostly causes this.  The
clocksource messages continue repeatedly until the domU is rebooted. 

The clock in the domU is stalled too.

I''ve reported it to Ubuntu:

https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.22/+bug/146924

Feel free to add any more information there to help the kernel
maintainers.

John.
-- 
http://www.brightbox.co.uk - UK Rails Xen Hosting

On Fri, 2007-09-28 at 17:01 +0900, Takeshi Sone wrote:
> Hello gurus,
> 
> I have two physical xen hosts and when I migrate a domU from one host to 
> another, I get many of this error from domU kernel:
> 
> clocksource/0: Time went backwards: delta=-3536123661 shadow=686019823475
offset=281887188
> 
> Sometimes domU time stalls and network stops working, but other times it
> gets working again.
> 
> The two hosts are using different platform timer source:
> 
> root@xen1test:~# xm dmesg|grep -i timer
> (XEN) Platform timer is 14.318MHz HPET
> 
> root@xen2:~# xm dmesg|grep -i timer
> (XEN) Platform timer is 1.193MHz PIT
> 
> Both hosts use Ubuntu Gutsy (latest as of today) packaged version of Xen
> 3.1.0, Linux 2.6.22 (on both dom0 and domU).
> 
> Dom0s are working flawlessly.
> 
> Thanks in advance,
> Takeshi
> 


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