Re: Timedrift in KVM guests after livemigration.

[Dor Laor <dlaor@redhat.com>]

On 04/19/2010 12:29 PM, Gleb Natapov wrote:
> On Mon, Apr 19, 2010 at 11:21:47AM +0200, Espen Berg wrote:
>> Den 18.04.2010 11:56, skrev Gleb Natapov:
>>
>>>> That's two different things here:
>>>> The issue that Espen is reporting is that the hosts have different
>>>> frequency and guests that relay on the tsc as a source clock will
>>>> notice that post migration. The is indeed a problem that -tdf does
>>>> not solve. -tdf only adds compensation for the RTC clock emulation.
>>>>
>>> It's -rtc-td-hack. -tdf does pit compensation, but since usually kernel
>>> pit is used it does nothing.
>>
>> So this "hack" will not solve our problem?

As I also stated, in the past the kvmclock MSRs were not sync upon live 
migration and it was fixed in 1a03675db146dfc760b3b48b3448075189f142cc ,
better check with the code.

>>
> If your guest uses RTC for time keeping it may help. Otherwise it does
> nothing.
>
> --
> 			Gleb.
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html