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SubjectRe: [PATCH] i386-pda UP optimization

* 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.

Ingo
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