Author: Slater Wold
Date: 10:30:11 12/09/03
Go up one level in this thread
On December 09, 2003 at 13:17:55, Robert Hyatt wrote: >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. Like I said, it was just a 'deduction'. I know you're pretty scientific, but this was just a rough comparison. I'd be confident in this statement however: "64-bits, depending on application, can speedup a typical chess program from 40% to 70%." Which is nice, considering it is practically 'free'.
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