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Subject: Re: Nodes per second........

Author: John Coffey

Date: 14:30:09 09/26/98

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On September 26, 1998 at 17:21:58, James Robertson wrote:

>What is a reasonable number of NPS for a program to search if it has an average
>sized evaluation procedure? I.E. what does Crafty get? Chessmaster? Comet? My
>program started out searching a very nice number of nodes per second, but as I
>added stuff that number decreased dramatically from about 600,000 to 160,000. By
>the time I finish the evaluation function (which is currently like 20 lines),
>I'm afraid it will be down to like 5,000 NPS on my P233! At what point should I
>get worried?
>
>James

This is an interesting question, because Robert Hyatt told me the other day
that it was the size of the tree and not the NPS that really matter.  When
I looked at the Crafty source code, I was surprised at how much code that
gets executed for every single node.  But the main purpose of that code is
to cut down the size of the tree (using null moves, hash tables, move ordering,
etc.) That tree  grows exponentially, so cutting it from say 6^N down to 3^N
is a huge improvement regardless of the number of nodes per second.

Fritz 5 is suppose to use about a 1,000 clock cycles per node.  Crafty gets
80,000 nodes on a Pentium 200 mmx, so that works out to be about 2,500 clock
cycles per node.  But Crafty is still very very strong.

John Coffey



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