Re: X15 alpha release: as fast as TUX but in user space (fwd)

H. Peter Anvin
2001-04-30T07:30:18Z

"David S. Miller" wrote:
>
> dean gaudet writes:
> > i was kind of solving a different problem with the code page though -- the
> > ability to use rdtsc on SMP boxes with processors of varying speeds and
> > synchronizations.
>
> A better way to solve that problem is the way UltraSPARC-III do and
> future ia64 systems will, by way of a "system tick" register which
> increments at a constant rate regardless of how the cpus are clocked.
>
> The "system tick" pulse goes into the processor, so it's still a local
> cpu register being accessed. Think of it as a system bus clock cycle
> counter.
>
> Granted, you probably couldn't make changes to the hardware you were
> working on at the time :-)
>

RDTSC in Crusoe processors does basically this.

-hpa

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