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Subject: Re: movegen speeds(was Re: Status of Brutus?)

Author: Angrim

Date: 13:53:27 07/30/03

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On July 29, 2003 at 17:00:05, Vincent Diepeveen wrote:

>On July 29, 2003 at 12:05:59, Angrim wrote:
>>
>>perft includes makeing moves, and checking moves for legality, so it
>>will be much slower than just generating pseudo-legal moves for the
>
>WRONG. you can do perft much faster.

see bottom of page for comments on perft.

>We have had this discussion before.
>
>Just generate after 1.e4,e5 2.d4,d5 the semi-legal move list about 10 million
>times. Then divide by the time needed.

This was what I did to get my 60meg moves per second number.
This can be a useful benchmark also, especially if you use multiple
different positions.

>note that perft is not storing the moves at all.

see bottom of page for comments on perft.

>major speed penalty.
>
>Now you try to get near a few tens of clocks move...
>
>>same position over and over.  I just coded up a routine to do a few
>>million calls to get_chess_moves() from the current position and
>>time it, and from the e4 e5 d4 d5 position I get the equivalent of
>>60meg moves per second on a 2ghz machine.  My perft only gets equiv
>>of 4.8 meg positions a second though, since my InCheck is pretty slow.
>
>>note that my Athlon is actually running at 1.15ghz currently, so I
>>multiplied my actual results by (2.0/1.15) to get 2ghz equivalent.
>>Angrim
>
>you're comparing the wrong things.
>
>perft goes at 1 billion moves a second when using a hashtable as we discussed
>here in CCC.... ...if it just runs long enough

I disagree, you can do something which outputs the same numbers as
perft does much faster with hash tables and tricks, but that isn't
perft, and is useless for benchmarking.
There seems to be an adequate definition of perft at:
http://homepages.caverock.net.nz/~peter/perft.htm

If someone wants to write a function that generates the same numbers
far faster, and call that perft, I think they are mostly just hurting
themselves, I certainly won't be paying any attention to them and they
won't be able to test the speed of their movegen and makemove against
other engines using that function.

Angrim



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