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Subject: Re: Hash hit rate?

Author: John Stanback

Date: 19:41:59 02/25/99

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On February 25, 1999 at 19:24:36, Steve Maughan wrote:

>What is a reasonable hash hit rate?  My program seems to have a low hit rate.
>From a new game position the hit rate is approx 7% ie 7% of probes result in a
>hit.  This is surely too low!?  Does anyone have an idea of what is reasonable?
>
>Thanks in advance!
>
>Steve Maughan
>
>PS I'm using a 2 hash system of Clever/Simple hash replacement.  I only probe
>the table once for each interigation ie I do not look at Offset+1, Offset+2 etc

I only get a 4-5% hash hit rate in Zarkov when searching the opening
position for about a minute.  I don't store or probe quisecence nodes,
but I do count them in the #nodes.  The percentage I calculate
is #hits/#nodes.  I compute 4 hash addresses and replace the "worst"
of the four entries, unless the entry is near the root of the tree and
current node is not.  I think this hit rate is ok.  It goes way up in
the endgame.

John



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