Author: Robert Hyatt
Date: 15:38:53 01/20/98
Go up one level in this thread
On January 20, 1998 at 16:02:27, Stuart Cracraft wrote: >On January 20, 1998 at 15:22:51, Robert Hyatt wrote: > >>On January 20, 1998 at 14:10:49, Stuart Cracraft wrote: >> >>>An error was discovered in the search/quiescence calling. >>> >>>The call to the quiescence search was made >>>after the probe to the hash table, instead of before. >>>When this was moved to before the probe to the hash >>>table, the probe success rate jumped up to the kinds >>>of levels we're talking about here. >>> >>>The speed of the program jumped up 20% from 25,000 nps >>>to 30,000 nps on the same test suite and the hashing >>>success rate increased significantly from 14% to 40% >>>for the suite. >>> >>>--Stuart >> >>Your "bug" was correct. You *always* probe before doing anything >>else. That's the point. What you did was make the current position >>probe fail by deferring it, so that a deeper position probe would >>succeed. You bumped up your probe hit rate, but check out your nodes >>to reach a specific depth. >> >>The probe should be the first thing you do. Then the null-move >>search. Then the regular search. > >Okay to test your hunch, I did a 6-ply search of the first 20 positions >from Win-at-Chess (unless it is a checkmate, which returns when found). > >In my old way: > > search(alpha,beta,depth,etc.) > : > : > Do transposition table probe > if (depth <= 0) quiescence(alpha,beta,etc.) > >With the above this is the search result for the 20 positions: > >Time = 51.7 Rate=24332 Nodes=[927630/329326/1256956] >EvalCnt=289750 RptCnt=276 NullCut=49186 >Extensions: Check=45027 Recapture=23718 Pawn=350 PassedPawn=0 > OneMove=0 Threat=0 DeepSearch=0 Mate=0 >Hash: Success=10% Collision=16% >Pawn Hash: Success=93% Collision=5% > >The new way: > > search(alpha,beta,depth,etc.) > : > : > if (depth <= 0) quiescence(alpha,beta,etc.) > Do transposition table probe > >With the new way, these are the results: > >Time = 46.0 Rate=27392 Nodes=[930731/329941/1260672] >EvalCnt=293997 RptCnt=271 NullCut=48967 >Extensions: Check=45281 Recapture=23840 Pawn=360 PassedPawn=0 > OneMove=0 Threat=0 DeepSearch=0 Mate=0 >Hash: Success=31% Collision=16% >Pawn Hash: Success=93% Collision=5% > >So for the cost of searching 10,000 more nodes (but at a higher rate), >I got a 10% improvement in total time with the new way. Am I missing >something? I still like the new way, even with more nodes. > >--Stuart try more positions, to much deeper depths. this is going to explode like nobody's business...
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