Re: [PATCH 5/5] KVM: paravirt time source

Anthony Liguori
2007-06-19T21:38:36Z

Jeremy Fitzhardinge wrote:
> Anthony Liguori wrote:
>
>> I've updated this patch and switched to using a scale/shift like Xen
>> is doing, but I must admit, I don't understand how it helps adjtime.
>> I poked around a bit and it wasn't obvious.
>>
>> Why is having {mult=1<<22, shift=22} better for adjtime than {mult=1,
>> shift=0}?
>>
>
> I don't fully understand it myself, but I think its because adjtime
> plays with the mult factor to scale the rate at which time passes. If
> the scale is 1, then it can only scale time by integer amounts. By
> setting it to 2^22, then it can adjust time down to 1 part in 4 million.
>

Ah, thanks.

Regards,

Anthony Liguori

> J