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Subject: Re: Slow EGTBs - test position

Author: Dieter Buerssner

Date: 13:15:56 01/16/03

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On January 16, 2003 at 15:37:07, David Rasmussen wrote:

        EGTB probes: 25055
                     ^^^^^
>1. Bxg5
>
>That is quite a speed drop. What I don't understand is that during this search,
>the disk is working like crazy. I only probe in the first 2 plys.

??
This doesn't seem to matter at all.

> There is 11
>legal moves in the position, so that's roughly 100 positions. That can't take
>that much activity to probe. And then I only probe within the iteration depth,
>and only then if there have been a capture or a promotion, and only if the
>number of pieces on the board is small enough (<= 5 for 3-5 man tables). In this
>position, there is of course a capture now and then, and a promotion sometimes
>too. But why this constant disk access?

Even for a fast disk, 25000 random accesses will take a long time. Many of those
will have been cached, otherwise it would even be much slower.

I get a similar slowdown and a comparable number of TB-accesses here with my
engine.

Just testing a position will not be a good test for normal games. There all the
caches will have time to "warm up". When you try the same position a second time
(of course again not a good test), you will probably see a big difference.

Regards,
Dieter




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