Author: Tord Romstad
Date: 10:02:22 09/25/03
Go up one level in this thread
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
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