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Subject: Re: Try RC5 w/ HT

Author: Aaron Gordon

Date: 20:40:23 05/23/03

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>What are they measuring?
>
>IE running two copies _should_ see each copy run about 1/2 as fast with SMT
>on, since each copy is getting roughly 50% of available cpu core resources
>when running the same instruction streams.
>
>Or do you mean something else?

It's keys per second for RC5, nodes per second for OGR. What I mean is it spawns
1 thread per processor (or virtual processor in HT's case).
My Dual Celeron 400MHz box gets an exact 2.00x speedup with this, I'm assuming
because it doesn't hit the main memory at all. Any other dual processor system
should also get a 2.00x speedup as well.. however I saw some results that were
puzzling. Here they are...

Dual Xeon (P4) 2.0GHz without HT - 2.8 million keys/sec per thread (5.6mk/s
total), 2 threads total.

Dual Xeon (P4) 2.0GHz with HT enabled - 0.72 million keys/sec per thread
(2.88mk/s total), 4 threads total.

I was just wondering if you could run the same tests and confirm this. I would
have figured RC5/OGR would have managed a nice boost from HT, so it's surprising
to me.



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