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Subject: Re: Hash table size

Author: J. Wesley Cleveland

Date: 10:01:11 06/25/99

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On June 24, 1999 at 15:35:18, Michael Fuhrmann wrote:

>On June 24, 1999 at 15:17:23, Chris Carson wrote:
>
>>On June 24, 1999 at 14:43:35, Michael Fuhrmann wrote:
>>
>>>	When setting hash table size, bigger is generally better (provided there’s
>>>enough memory). Except for blitz, when bigger is unnecessary, right?
>>>	So what would be an appropriate hash table setting for blitz? I’m thinking
>>>specifically of Crafty, but guess the same figure would be OK for other engines
>>>...
>>
>>I use the following rule (for Crafty and CM6K), take the Nodes Per Second
>>for your program (run Bench for Crafty, 180K NPS for my PII 300 for Crafty
>>and 20K NPS for CM6K).  Determine the amount of time you will give the
>>computer on average.  I play about 1 min per move so for Crafty I set
>>the hash=180K NPS * 60 sec = about 12M and hashp=3M.

You seem to be forgetting that that 12M is bytes and not table entries. For the
case of Crafty, you need to multiply by 16.

>So in the case of, let's say, a 5 min game, when Crafty has 300 seconds to make
>all its moves: Should I divide 300 by 40 (average number of moves per game), to
>get 7.5 seconds (average time per move) and then multiply that figure by NPS?
>
>And if ponder is on, I guess the figure should be higher?
>
>>
>>For CM6K  ttable=20K * 60 = 1.2M = I round up to 2M = 21
>>
>>Hope that helps.  Basically determine how many nodes will be evaluated
>>on average and set the hash tabel to be that size.  Just my opinion.
>>
>>Best Regards,
>>Chris Carson



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