Kevin Lawton wrote:
>
> Ramon van Handel wrote:
>
> > Uh, you mean the lapic timer ? Not that I can see..
> > Not in a reliable way, anyway.
>
> Yeah the Local APIC timer. Humm, I'll have to read up
> on it more. With timers in general, you can multiplex
> them. Given you know when they're supposed to go off
> next (according to the host OS view), we might be
> able to take a time sampling, and store away the
> current LAPIC timer settings. Then run the guest for a timeslice.
> Once the timer hits, we'll be back in the
> host kernel module to handle the interrupt redirection
> and thus can take another sampling, and restore the LAPIC
> timer back to some sensible value considering.
> Since we know how long we were in the guest context due
> to our time samplings with RDTSC, we can increment the
> LAPIC timer based on this so it's accurate from the
> host's perspective.
Why can't we just do this with the PIT, then ?
Doesn't sound extremely reliable to me, but for a timesharing
host system it should do.
Ramon
