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Subject: Re: Are bitboards really faster on 64-bit hardware?

Author: Matthew Hull

Date: 13:35:04 11/06/03

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On November 06, 2003 at 16:26:15, Dann Corbit wrote:

>On November 06, 2003 at 15:55:10, Russell Reagan wrote:
>
>>In this thread:
>>
>>http://www.chess-archive.com/ccc.php?art_id=310212
>>
>>Gian-Carlo Pascutto reported that his program, Deep Sjeng (compiled for 64-bit
>>hardware), ran 70% faster on an Opteron, clock for clock. As far as I know, Deep
>>Sjeng is not bitboard based.
>>
>>In this thread:
>>
>>http://www.talkchess.com/forums/1/message.html?325912
>>
>>Eugene Nalimov reports that Crafy (compiled for 64-bit hardware) gets 1,761,569
>>nps on a 1.8GHz Opteron. On my 2GHz Athlon, Crafty gets 1,230,931 nps.
>>
>>(2.0 / 1.8) x 1,761,569 = about 1,957,298 nps on a 2GHz Opteron
>>
>>So, clock for clock, Crafty is 1,957,298 / 1,230,931  = 1.59 times faster (60%)
>>on an Opteron, while Deep Sjeng was 70% faster. I suspect Eugene was using his
>>magic unreleased compiler also, which probably produces faster executables than
>>gcc. But that is speculation.
>
>I doubt if it creates faster executables than GCC for 64 bit systems.  64 bit
>GCC will be much more mature than MS VC++.NET for Win64, since there have been
>64 bit systems around for years, and these often use GCC.  Win64 is still beta.

I have the impression from previous discussions that GCC making slower
executables has more to do with philosophical approach than to experience on
architecture.

MH

>
>>So either Deep Sjeng is bitboard based, or the expected advantage that bitboard
>>engines were going to get that non-bitboard engines were not going to get does
>>not exist. Or I'm overlooking something else.
>>
>>Thoughts?
>
>My second thought is that it shows move generation is not the bottleneck in
>crafty.  Probably, evaluation is also not dominating, since tons of bitboard
>math will be done there also.



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