Author: Ed Trice
Date: 20:17:04 11/10/05
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The hash table reduces the size of the game tree. The larger the hash table, the quicker you can reach a certain depth. There is a diminishing return, however, largely depending on the search time. For example, at 5 seconds per move, a 1 GB hash table (1024 MB) will not offer any tangible gain over a 8 MB hash table. Longer matches, bigger hash tables, better results. The endgames are encountered so rarely during a search that a 16 MB settting would be more than sufficient, with 8 MB probably being as effective. Even though the number of positions in the tablebases are huge, by the time the program reaches where they are useful, there is excellent "locality of reference", and only the thin sliver that will occur from that point forward will be loaded into your RAM buffer. I would say 64 MB hash for each program, 8 MB TB Cache, and you will be at a fully optimized setting for short time controls. The reason for smaller hash tables: each move they must be "initialized", and looping through large hash tables on shorter time controls will leave you will about half a second less time per move. >Hello Chesscomputerfriends! > >I just a bought a new PC and I'm ready to make a lot of Enginematches (Pondern >OFF) which will result in a kind of Ratinglist. But now before starting I am >having some doubt of how much Hash Table size and TB Cache I should use to >optimize the performance of the Engines. I'm using the complete 3+4 TB's that >are included on the Shredder 9 CD and I have copied them to my Hard Disk (size: >app. 30 MB). You should know the following of my tests and new PC: > >- I'm doing testmatches with 5+5 thinkingtime, that means an average thinking >time of 10 seconds per move provided that an averagegame is 60 Moves. > >- Here are some basic facts of my new PC-system: > >Asus A8V, socket 939 Motherboard >AMD Athlon 64 4000+, The quite new San Diego core (only 90 nm), 2.4 GHz, 1 MB >Level 2 Cache >2 x 512 MB Corsair TwinX 3200 XLPT, PC3200 Ram, CAS Latency 2-2-2-5 >Windows XP operative system > >The reason I bought these High Peformance Ram is that I read a review of my new >CPU in which it was emphasized that fast memory is imperative due to the fact >that the memory controller is integrated in the CPU. Hence, fast memory should >make a real difference. > >Based on these informations; which size of Hash Tables and TB's Cache would you >recommend? My sugest: 128 MB HT for each engine and 32 MB Cache for the TB's (or >maybe 16 MB are sufficient??). > >Best regards >Per Jørgensen, Denmark
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