Author: Tony Werten
Date: 01:54:29 04/19/03
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On April 19, 2003 at 04:07:37, Uri Blass wrote: >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? No, because you're doing more then, wich can go faster with faster hardware. ie You don't reach the move generation bottleneck, but have others. But if all you are doing, has a memory bottleneck (wich happens when only generating moves with bitboards ), a faster cpu won't help very much. Tony > >If pentium933 give you the same speed as faster hardware then there is no reason >to use new hardware. > >Uri
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