Author: Robert Hyatt
Date: 10:17:55 12/09/03
Go up one level in this thread
On December 09, 2003 at 13:04:01, Slater Wold wrote: >On December 09, 2003 at 12:49:17, Robert Hyatt wrote: > >>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. > >Well, we can always deduct. :) > >An opteron 144 (1.8Ghz) running SuSe and gcc33, using -m32 to produce 32 bit >code, got these results on 186.crafty: We can't compare with that at all. That is a _way_ old version, obviously. I can't do -m32 on this machine, as the libraries are all -m64 and they become incompatible (I have already tried this a few days back in fact.) > >90.1 1109 > >The fastest 2.8Ghz Xeon on SPEC's website does: > >92.0 1087 (2k AS IC++ 7.0 compiler) > > >For all practical purposes, we can say that a O144 a P4 2.8Ghz Xeon are >'comparible'. OK. Can't argue there with no data of my own to rely on.. > >1.0M to 1.6M = 60% speedup Not directly attributable to 64 bit however. -m32 restricts you to 8 registers, while -m64 adds the other 8. That also factors in and makes this less clear.
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