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SubjectRe: Clock jumps
On 05/26/2010 11:31 AM, Alexander Graf wrote:
> On 26.05.2010, at 19:10, Orion Poplawski wrote:
>> On 05/25/2010 12:21 AM, Gleb Natapov wrote:
>>> Adding kvm to CC.
>>> On Mon, May 24, 2010 at 04:06:32PM +0000, Orion Poplawski wrote:
>>>> I have a KVM virtual machine running on a CentOS 5.5
>>>> host whose clock jumps about 8-12 hours a couple times a day. I have no idea
>>>> what is causing it. Fedora 12 and Centos 5.5 KVM machines run fine on the same
>>>> host. Is there any debugging I can enable to see what is jumping the clock?
>>>> kvm-clock: cpu 0, msr 0:1ba4741, boot clock
>>>> kvm-clock: cpu 0, msr 0:1e15741, primary cpu clock
>>>> Switching to clocksource kvm-clock
>>>> rtc_cmos 00:01: setting system clock to 2010-05-20 16:59:48 UTC (1274374788)
>> Thanks, though I don't think it made it there. I'm also not sure it's completely limited to KVM, though that is the only running system I am currently seeing the problem on. I also see clock jumps during anaconda installs on physical hardware and apparently they have been present since at least F11. Might be unrelated though.
>> I'm really at a loss of how to debug this though.
> Do you have ntpd running inside the guest? I have a bug report lying around about 2.6.33 with kvm-clock jumping in time when ntpd is used:
> Alex

That bug looks just like what I'm seeing. I even see the soft lockup messages
sometimes as well. May actually be seeing it with a Fedora 12 guest as well -
but it results in a hard hang.

Orion Poplawski
Technical Manager 303-415-9701 x222
NWRA/CoRA Division FAX: 303-415-9702
3380 Mitchell Lane
Boulder, CO 80301

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