Author: Albert Bertilsson
Date: 00:04:23 12/13/03
Go up one level in this thread
On December 12, 2003 at 17:29:18, Dieter Buerssner wrote:
>The performance of your program seems quite comparable to my program using hash
>tables for perft. I store the whole position, to be really sure (for faster
>perft runs, the overhead óf doing this seemed not too high). I get on P4, 2.53
>GHz, 350e6 bytes for perft HTs:
>
>white ( 1): perft 6
>entries 5468750 size 350000000 size_wanted 350000000
> 6: 119060324
>Used 2.588 s
>white ( 1): perft 7
>entries 5468750 size 350000000 size_wanted 350000000
> 7: 3195901860
>Used 32.301 s
>white ( 1): perft 8
>entries 5468750 size 350000000 size_wanted 350000000
> 8: 84998978956
>Used 427.989 s
>white ( 1): perft 9
>entries 5468750 size 350000000 size_wanted 350000000
> 9: 2439530234167
>Used 8929.689 s
>
>I used the following struct for hash:
>
>#define EXACT_PERFT 1
>#define N_PERFT_DEPTH 2
>
>typedef struct perfentry
>{
> unsigned long hash32;
>#if EXACT_PERFT
> unsigned char real_bd[32];
>#endif
> double nodes[N_PERFT_DEPTH];
> unsigned char depth[N_PERFT_DEPTH];
>#if EXACT_PERFT
> unsigned char castle_flags;
> signed char epsq;
>#endif
>} PERFENTRY;
>
>So, each entry could store two depthes and node couunts. I only used 32 bits for
>the first compare of position, and if the same, compare the whole board. In the
>perft 9 run, there was no collision (all matching hash keys also gave a matching
>position). I used another 32 bits of the hashkey to calculate the index in the
>table. The program also considered index+1 and index+2 (when storing, it may
>overwrite the entry with the lowest depth - when probing it will look at all
>three entries). I did not tune it really, just started with this idea. Perhaps a
>more simple scheme would work better.
>I used double as a counter. With typical modern floating point implementations,
>this will work well, until counters hit 2**54.
>
>Regards,
>Dieter
The idea of storing multiple depth/node counts for each position is quite clever
considering that the board takes most of the struct anyway. I think I'll try
that too :)
Your program actually seems a bit faster than mine. If perft(12) becomes real
would you consider letting the project use your exe? (It would only require a
known commandline interface).
/Regards Albert
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