On Fri, Apr 4, 2008 at 4:33 PM, Jan Kiszka <[EMAIL PROTECTED]> wrote:
> Gilles Chanteperdrix wrote:
> > Right. We are approximating a fraction with another fraction. But my
> > first impression remains: I do not like the idea of making
> > xnarch_ns_to_tsc wrong because xnarch_tsc_to_ns is wrong.
> >
>  Well, my first impression was originally the same: If we still need llimd
> in the ns-to-tsc patch, then we should keep the precise way. But that was
> wrong as this thread demonstrated. We have to ensure that
> ns_to_tsc(tsc_to_ns(x)) remains x with only minor last-digit errors. So
> either use scaled math parameters in both ways or fall back to the original
> calculation.

Now that I think about it, this scaled math approach is about taking
an approximation of the CPU frequency, which is already approximative.
So, I will not oppose longer to your patch.

>  However the final decision for 2.5 is (pro or contra scaled math), at least
> for 2.4.x we have to fix things now without turning the upside down. That
> means apply my patch or revert scaled-math optimizations for all archs.


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