Re: [Xen-devel] HPET/PIT timer accuracy

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 29 Jul 2005, at 19:29, Ian Pratt wrote:

> > We're not relying on TSC synchronisation between CPUs. They
> > can run at different frequencies, stop in deep sleep, and so
> > on. But we *do* want the frequency of each one to be as
> > stable as possible. I'd expect to get <1ppm stability from a
> > crystal source at constant temperature, no problem.
> I'd wager the TSC is stable and it's the HPET that's wandering...
>
> We'll probably just have to add more damping on the re-calibration.
I haven't done any further tests to see how low the frequency of 
wandering goes. Perhaps we'll find the platform timer is more stable 
over e.g., 60s periods.
 -- Keir


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel