Re: Intel P6 vs P7 system call performance

Pavel Machek
2002-12-19T22:15:09Z

Hi!

> >>don't many of the multi-CPU problems with tsc go away because you've got a
> >>per-cpu physical page for the vsyscall?
> >>
> >>i.e. per-cpu tsc epoch and scaling can be set on that page.
> >
> > Problem is that cpu's can randomly drift +/- 100 clocks or so... Not
> > nice at all.
> >
>
> ­­?100 clocks is what... ?50 ns these days? You can't get that kind of
> accuracy for anything outside the CPU core anyway...

50ns is bad enough when it makes your time go backwards.

Pavel
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