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Subject: Re: Hashtables: is larger always better?

Author: Vincent Diepeveen

Date: 10:20:01 09/23/01

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On September 22, 2001 at 22:03:17, Robert Hyatt wrote:

>On September 22, 2001 at 18:29:46, Andreas De Troy wrote:
>
>>When I see results for the so called "Fritzmarks", I notice that the actual
>>numbers decrease with increasing hashtables. Is this an artefact of the
>>measurement? In other words, are larger hashtables always better? I suppose it
>>depends of the speed of the processor. If you have, for instance an Athlon 1 Ghz
>>(or a 1.5 Ghz or...), does it -in general- make sense to increase the size of
>>the hashtables to 256 Mb, 512 Mb or more?
>>
>>Thanks in advance for any help!
>
>
>You are comparing apples and oranges.  Apples = NPS, oranges = time to
>reach a specific search depth.  Larger hash tables will slightly lower
>NPS for some programs.  But it will speed up time-to-ply, until the hash
>becomes too large.  At that point, no further improvement will be seen,
>but larger won't hurt at all unless you go so large you cause paging.

I have never seen a 'hashtable too large'.

I only know that hashtable mercilous punishes forward pruning experiments
when talking about branching factor in the long run.





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