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

Author: Russell Reagan

Date: 12:55:10 11/06/03


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.

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?



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