Messages in this thread | | | Date | Wed, 15 Nov 2006 18:20:03 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] i386-pda UP optimization |
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* 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.
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