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Subject: Re: Question for the KING: TT sizes

Author: Johan de Koning

Date: 19:21:39 01/24/04

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On January 23, 2004 at 15:14:04, Rajen Gupta wrote:

>hi johan:
>
>i have a pentium 3, 1.2 ghz with 512 mb ram
>
>i normally use just below half of this as hash for chessbase engines at long
>time controls.
>
>as per your previous suggestion (through indirect sources) i have come to
>believe that 64 mb is optimum for the king3.23 (running as a UCI engine in the
>chessbase interface.

Because clearing the TT takes some time, there used to be a problem
with huge TT *and* fast time controls. However, the clearing has been
optimised as of TK 3.12d (CM8000 final patch, summer 2001), and the
problem is non-existant since then.

Well, there is still the fact that random RAM access slows down with
increasing size. But that's a complicated hardware issue that applies
to all engines. Depending on the machine and the engine it will be
just noticeable or just not.

>is this correct or should i use a higher figure?

Can? Yes, no problem.
Should? No, only for loooong time controls.

My rule of thumb for The King (being a slow searcher) is to allocate
1 byte per *average* node searched. That's simply enough.

Example1
PIII/1200                      does 150 kN/s
Time control game/10 minutes   does 10 seconds on average.
TT = 1.5 MB                    does the job.

Example2
AMD 3000+                      does 400 kN/s
Overnight analysis             takes e.g 36 ks
TT = 1 GB                      is smallish, but hey, there are limits!

... Johan



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