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Subject: Re: move_generation + hash

Author: Tom Kerrigan

Date: 16:44:05 05/28/00

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On May 28, 2000 at 10:02:05, Georg v. Zimmermann wrote:

>Hi,
>
>today I realized that the program I'm toying around with does in its search()
>
>1.) generate all moves
>2.) order the moves and put hash move if available to 1st position
>3.) do the recursive search
>
>I thought that I could increase its speed by testing the hash move first and
>only if not >= beta do the move generation and the rest.
>
>From my tests it shows that it sticks with the hash-move about 50% of the time.
>Should this number be higher ?
>
>I was very dissapointed when I didn't notice any speedup after my changes. What
>speedup should I expect ? Something like 0.5-1% or more like 1ply ?

You can forget about 1 ply. Your program needs to go ~4x faster for it to search
1 ply deeper. Which means that your move generator must be taking ~400% of the
execution time, which is clearly impossible.

Here's what you have to consider when calculating your speedup:

1) How many moves you get from the hash table. I just ran some random position
and got a 1.75% "hit rate."

2) How many times your optimization will be effective. You said 50%.

3) How much time your move generator takes. Let's just say 20%.

So, I bet your speedup is somewhere around 0.175%, which is probably why you
didn't notice it.

-Tom



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