Author: Bas Hamstra
Date: 13:07:51 01/16/03
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Hi Scott, I have exactly the same problem with Tao and the same cause. In my case I assign SEE values to all qcaptures and sort them. That kills nps but improves movesorting. From earlier experiments I know that simply sorting MVV/LVA, while maintaining the skipping of SEE losing captures, boosts nps, however in my case the measured overall searchdepth remained about the same. So I don't worry to much about it. As Bruce expressed it once, you simply run at a lower "gear". Best regards, Bas. >Hi, > >Bruce's recent posts about code efficiency have had the opposite affect he >intended, on me at least. I've been profiling and looking to trim the fat from >my code since reading them. I have made some progress, I'm glad to report. > >As part of these experiments I enabled a material-only eval routine. Running a >raw speed test with this simple eval I noticed my engine still was only about as >fast as "fast" engines on the same machine. Engines like yace/crafty/ruffian >seem to run about as fast on my machine as my poor engine does with only a >material count eval. This indicates to me that I am generating and scoring >moves too slowly. > >So I profiled my engine with the material only eval and found that it is >dominated by the SEE code. This is partially my own fault because I have a >pretty complicated SEE that handles stuff like accurate pawn promotion scores, >pieces that can't participate because they are pinned against the king, >attackers/defenders exposed in the middle of the exchange, etc. > >My question for those of you with fast move generators, especially those using >SEEs to score moves, is how do you do it? Vincent said something to me about >not scoring all the moves generated which doesn't make any sense (at least to >me). I don't run the hash move through the SEE since I am going to try it first >anyway. And I won't bother to send PxQ through the SEE, clearly it's a winning >move. I send all promotions, apparently even captures, and apparently losing >captures though the SEE though to make sure I have a score on every move >generated, though. I do this because when I go to pick the next best move out >of the list I need to know the score of every move generated. Am I missing some >trick here? > >I have a feeling that monsoon is due for a major code revision after CCT5... I >have a bunch of ideas I want to try like: parallel search, incremental attack >tables instead of an SEE, better POSITION data structure, etc... Thanks for any >and all advice. > >Scott
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