> Hmm, so if K6 and Xeon can scrounge up 80% of pipe
> performance, why is the Athlon an order of magnitude off
> at 8%? How did your Athlon perform in other tests relative
> to these other procs?
The pipe test basically tests copy_from_user()/copy_to_user().
The standard implementation of these macros (essentially rep ; movsl)
doesn't exploit the Athlon very well - it is not good at this
instruction. AFAIK Intel CPUs have an faster microcode
implementation for this.
You could likely do better on Athlon with a copy*user that uses
an unrolled loop with explicit movls or even SSE.
[similar to the implementation the x86-64 port uses, but without
the NT instructions]
-Andi
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