Re: [RFC] Paravirt timer for KVM

Hollis Blanchard
2007-10-15T23:05:40Z

On Mon, 2007-10-15 at 18:47 +0200, Avi Kivity wrote:
> Hollis Blanchard wrote:
> >>
> >> I'd think there is no reason for virtual timer to be PIT like, which
> >> is mostly due to historic reason.
> >>
> >> If we need to make it close to native timer device, HPET is much
> >> better than PIT for virtual time to look like.
> >>
> >
> > Fine, so why do we need PV time when we can emulate the HPET?
> >
>
> A pv timebase can require zero exits while any emulated timebase will
> require at least one.

That's a good point, but does PIT/HPET emulation show up as a hot spot
in any profiles? I think keeping the hypercall API as small as feasible
is a desirable design goal.

--
Hollis Blanchard
IBM Linux Technology Center