> > It's not as good as a pure user-mode solution using tsc could be, but
> > we've seen the kinds of complexities that has with multi-CPU systems, and
> > they are so painful that I suspect the sysenter approach is a lot more
> > palatable even if it doesn't allow for the absolute best theoretical
> > numbers.
>
> 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.
Pavel
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