Author: Tony Werten
Date: 22:03:33 09/25/03
Go up one level in this thread
On September 25, 2003 at 13:02:22, Tord Romstad wrote: >On September 25, 2003 at 11:28:55, Robert Hyatt wrote: > >>On September 25, 2003 at 09:48:33, Tord Romstad wrote: >> >>>On September 24, 2003 at 16:28:57, Robert Hyatt wrote: >>> >>>>I try to use _most_ of main memory for serious games, and if you have a >>>>1 gig machine, I generally use something like hash=784M, hashp=40M, >>>>cache=128M, and go from there... >>> >>>Interesting. Is a 40M pawn hash table really useful for Crafty? How big >>>are your pawn hash entries? My pawn hash table contains just 256 entries, >>>where each entry is 128 bytes. The last time I tried, increasing the size >>>of the table gave just a very small speedup (less than 2%, if I recall >>>correctly). >>> >>>Tord >> >> >>I've never carefully tested this, but 256 entries seems _way_ small. Just >>look at how many different possible pawn positions there are. > >I decided to experiment with this again. I let my engine analyze the >position after 1. d4 d5 2.c4 e6 3. Nc3 Nf6 4. Bg5 Be7 to a depth of >10 plies with different pawn hash table sizes. Here are the results >(the first column is the number of entries, the second column is the >number of seconds needed to complete 10 plies): You should add 0 entries I think because going from 0 to 1 will give you the biggest speedup. My guess is that the searchtime for 0 will be even above 90s 1 entrie will already mean that you remember the pawnstructure of the parent node, wich is most usefull. Specially if you exclude silly captures (QxP, PxQ ) in quiescence. Tony > > 1 70.59s > 2 60.08s > 4 58.28s > 8 57.25s > 16 55.74s > 32 55.24s > 64 54.38s > 128 54.18s > 256 53.76s > 512 53.53s > 1024 53.32s > 2048 53.05s > 8192 52.68s > 16384 52.25s > 32768 52.09s > 65536 51.87s >131072 51.82s >262144 51.85s >524288 51.88s > >As you can see, the speed gain by increasing the number of entries from >256 is not very big, and increasing the size beyond 65536 entries seems >completely useless. > >Of course, it is possible that a different position would have given >different results. > >Tord
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