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Subject: Re: Speedups for BitBoard programs on 64-bit machines

Author: Alessandro Damiani

Date: 03:39:14 06/07/02

Go up one level in this thread


On June 06, 2002 at 20:35:03, Robert Hyatt wrote:

>On June 06, 2002 at 19:47:14, Vincent Diepeveen wrote:
>
>>On June 06, 2002 at 10:25:25, Robert Hyatt wrote:
>>
>>>On June 05, 2002 at 17:31:45, Gerd Isenberg wrote:
>>>
>>>>On June 05, 2002 at 13:22:30, Vincent Diepeveen wrote:
>>>>
>>>>>On June 05, 2002 at 04:14:41, Gerd Isenberg wrote:
>>>>>
>>>>>Gerd, a 33% speedup isn't much if you first slow down 2 times.
>>>>>Right now the crafty datastructure is exactly 2 times slower doing
>>>>>what i can do without bitboards.
>>>>>
>>>>
>>>>Vincent, if, as you claim, bitboarders are two times slower per se on 32bit
>>>>hardware, then i expect a speedup of >= 100% with bitboards on 64bit hardware.
>>>>
>>>>Gerd
>>>
>>>
>>>This argument goes in circles, because he also claims they are not very
>>>good on 64 bit machines either...
>>
>>Not really. the problem is the bitboarders have a different goal it seems.
>>If all you want is a Sum(squaresattacked) as mobility function, then sure
>>bitboards are an interesting thing to use at 64 bits processors. If you want
>>more, then bad luck with bitboards. Factor 2 slower.
>
>based on what?  Your lack of experience with them or proof that there are
>some things that bitboards can't do?  I know the latter is not true...
>
>Why do you want to waste so much time trying to explain why this approach
>is bad, when you have not tried it yourself.  It takes time to get used to
>it.  once you do, you discover that a lot of those "problems" are imaginary
>only.
>

It seems to me that Vincent tries to convince himself that bitboards are worse
than his approach.

Regards,

Alessandro



>
>
>>
>>At 64 bits processors 33% faster, still like 1.6 times slower.
>>
>>Best regards,
>>Vincent
>
>
>Again, what single cpu machine at 1ghz can run crafty at 1.5 M nodes per
>second?  Absolutely none unless we go to a Cray.  Or a Mckinley 64 bit
>processor...



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