Author: Uri Blass
Date: 08:59:10 09/26/03
Go up one level in this thread
On September 26, 2003 at 09:49:49, Gerd Isenberg wrote: >On September 26, 2003 at 07:01:49, Ricardo Gibert wrote: > >>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): >>> >>> 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 >> >>This is a surprise! > >Not for me, even with a one entry Pawn hash you got a lot of hits, >as Tony already mentioned. Try fine70 with one entry ;-) In that position I have no calculations of pawn structure also with 0 entries when I do or undo moves that pawn structure is not changed. Uri
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