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Subject: Re: Hash effects on knowledge vs. search

Author: Chris Carson

Date: 10:43:27 11/14/97

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On November 14, 1997 at 13:10:50, Ernst A. Heinz wrote:

>On November 13, 1997 at 22:35:43, Robert Hyatt wrote:
>>
>>I'd like to see data on this topic.  For example, in a typical opening
>>or middlegame position, 30% hash hits is *very* good.  there is *lots*
>>of stuff that is stored and *never* used again, due to the way the tree
>>is traversed.  I depend on the hash stuff a lot, but in normal
>>middlegame
>>positions I don't see any huge performance issues at all.  IE I don't
>>think
>>the difference between the biggest table I can use (96mb) and the
>>smallest I
>>ever use (1mb) is more than 10-15% at best.  Perhaps in endgames this
>>goes
>>up.  I'm going to try to run a small set of positions with various sizes
>>of hash tables to see what happens.  But I can't believe (except for
>>some
>>endings) that we are talking even 50% speed changes...
>
>For fast time controls, your above statement is certainly true.
>
>For tournament-type time controls, however, I know *many* positions
>where



Could you post one or two of these?  THANKS!  :)



>"DarkThought" really hits some kind of "hash wall" when doing about 200K
>nps.
>
>In these positions, time to solution greatly decreases (up to 50%) when
>doubling the hash table size from 64MB to 128MB.
>
>=Ernst=

Best Regards,
Chris Carson



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