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Subject: Re: CM8000, 101 patch - still too many engines running

Author: John Merlino

Date: 11:17:33 03/05/01

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On March 04, 2001 at 18:03:00, Elizabeth Schwartz wrote:

>On March 03, 2001 at 15:20:31, John Merlino wrote:
>
>
>>Thrashing will affect game play in that the Chessmaster GUI (and any engines
>>that it is running AND any other programs that are also running) will all slow
>>to a crawl as Windows tries to fulfill a memory allocation/free request that
>>requires a great amount of other memory to be swapped out. I'm sure you
>>understand this.
>
>Yep, that's the part I *do* understand.  The part I don't understand is exactly
>how, *assuming a machine with sufficient resources* various parameters relate to
>how well the game plays chess. Is the size of the hash table what limits how
>many moves deep the machine can look, or is there another relationship?

Apart from the personality settings (selective search, randomness, piece values,
etc.), which is an entirely different discussion (and there are MANY different
combinations of settings that people have touted the "best"), the hash table
defines how much memory the engine can use to store its thinking data (the
lines/positions that it has already analyzed). The more hash table hits, the
faster the analysis (although there is the question of diminishing returns as
you allocate more and more memory, which the engine has to keep track of).

Johan, as far as my memory serves, uses a hash table of 16MB when The King goes
into tournaments. I may be wrong about this, but that's what I recall the last
time he told me about it. Actually, he MIGHT have said that 16MB is a good
"all-around" setting, so I may be confused with the context of his statement.
But, I'm sure you get the idea.

The Chessmaster default personality (and, actually, ALL personalities that have
a hash table setting) uses only 1MB. This is to protect our typical non-computer
literate users.

The engine will look as deep as it believes it has time to look, regardless of
the hash table size. The hash table is just there to allow the program to see
more positions faster due to hash table hits.

jm



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