Author: Robert Hyatt
Date: 09:49:17 12/09/03
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On December 09, 2003 at 12:33:20, Slater Wold wrote: >On December 09, 2003 at 11:49:19, Mathieu Pagé wrote: > >>On December 09, 2003 at 11:16:02, stuart taylor wrote: >> >>>Is 2.2 Ghz. of a 64-bit computer a similar speed for chess as is 4.4 is it were >>>a 32-bit one? >>>If not, what? >>>S.Taylor >> >>Hi! >> >>No, it is not. >> >>64-bit computer are not twice as fast as 32-bit ones. The number of bit >>represent the natural lenght of an number on a cpu. Since chess engines use lot >>of 64 bits numbers they will run faster on 64 bits machines because on 32-bit >>machines they have to do some trick to do 64 bits maths that are natural on a 64 >>bit cpu. >> >>I dont think the improvement will be in the range of 2x speed up. Anyway it will >>vary from diffrents engines. >> >>Mathieu > >GCP reported 70% with Sjeng. > >Bob has reported about 50% with Crafty. Not exactly. I reported 1.0M with a 2.8ghz xeon, vs 1.6M with a 1.8ghz opteron. If you factor in a clock speed equalization, the xeon slows to 1.8ghz and would produce about 650K nodes per second and the opteron would be more than 2x faster. I have not done a direct comparison of 32 bit code vs 64 bit code on the opteron as I have no 32 bit compiler available there. If I get to do that at some point it time, it would be interesting. It would be more interesting to be able to say "use only 32 bit ops, but use all 16 registers" to get a _real_ feel for what 64 bits offers over 32 bits, but that looks even harder to test.
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