Author: Uri Blass
Date: 01:07:37 04/19/03
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On April 19, 2003 at 03:37:06, Tony Werten wrote: >On April 17, 2003 at 20:35:35, James Robertson wrote: > >>Out of curiosity I tested just the move generation and basic board functions of >>my bitboard chess program on several different computers. My home computer is a >>Pentium 933mhz, and the other computers I used were Athlons in the 1.6ghz range. >> >>My program's move generator runs at roughly the same speed on both systems. I >>was surprised and tested using several different compilers (VC5, VC6, .NET, >>gcc), under Windows and under Linux. To compare more easily, I wrote a simple >>non-bitboard move generator and tested this on all of the machines. The speed >>differences scaled with the speed of the processors, which seemed logical. >>However, I still cannot explain why the bitboard functions are so much slower on >>the faster computers. The only difference I can see is that my home computer is >>a pentium and the others are athlons. >> >>It seems strange that this would make such a large difference. Can anyone give >>any reasons why? I used no assembly, just C/C++ code, with all the default >>compiler options on all tests. > >I think it's because bitboards tend to fill up the caches, so memory becomes the >bottleneck. > >With other approaches this doesn't happen, ( until you add the big stuff like >eval ) so all things stay in chache wich makes it (almost) only processor >limited. > >Tony Does it mean that bitboard chess programs or programs with big evaluation are basically optimized for the old hardware because they cannot get much from new hardware? If pentium933 give you the same speed as faster hardware then there is no reason to use new hardware. Uri
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