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SubjectRe: [PATCH] i386-pda UP optimization
Date
On Wednesday 15 November 2006 18:20, Ingo Molnar wrote:
>
> * Andi Kleen <ak@suse.de> wrote:
>
> > On Wednesday 15 November 2006 12:27, Eric Dumazet wrote:
> > > Seeing %gs prefixes used now by i386 port, I recalled seeing strange
> > > oprofile results on Opteron machines.
> > >
> > > I really think %gs prefixes can be expensive in some (most ?) cases,
> > > even if the Intel/AMD docs say they are free.
> >
> > They aren't free, just very cheap.
>
> Eric's test shows a 5% slowdown. That's far from cheap.

I have my doubts about the accuracy of his test results. That is why I asked
him to double check.

-Andi
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