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Subject: Re: Improvements in BF makes my MoveGen suck =(

Author: Sune Fischer

Date: 07:46:08 06/27/03

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On June 27, 2003 at 08:13:53, Albert Bertilsson wrote:

>Just wanted to share my latest findings and warn you from making the same
>mistake (or maybe I just point out the obvious).
>I've always been proud to have a very fast movegen, doing perft calculations
>very fast. I optimized the movegen alot, and always saw playing strength
>increasing. I use a legal move generator and always saw the cost of verifying
>legality to be minor. Lately however I've noticed that the engine performance
>isn't that great (compared to other engines) inspite of the fast movegen. So I
>started digging today and the numbers struck me as lightning...
>As I've improved moveordering very much with hashtable/iterative deepening,
>killer moves and history tables the effective BF is now much lower. The lower BF
>now means that very few moves of all the generated ones are actually ever made.
>This means that the cost of generating legal moves have increased incredibly
>It's really anoying to notice that something you though was very good now is on
>the list of improvements again =(.
>/Regards Albert

What that saying with premature optimization being the root of all evil? :)

Well it think it is correct, and probably a typical mistake to spend oceans of
time optimizing one thing only.

I found a good post by Bruce Moreland about that, I just can't say it any better
myself :)


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