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

Jeremy Fitzhardinge
2007-06-19T21:26:38Z

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.

J