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Subject: Re: speed question

Author: Uri Blass

Date: 11:13:47 02/19/03

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On February 19, 2003 at 13:57:41, Dann Corbit wrote:

>When you want to make your code faster, the most important thing is to find out
>where it is slow.  I don't know how familiar you are with profiling, but a good
>profiler will show you a lot about your algorithms.  On most programs, and
>certaintly for chess programs, most of the time will be dominated by a few hot
>spots.  If you spend the effort on the hot spots, it will be enormously more
>beneficial than in other places.
>
>Nuts and bolts tweaky sorts of things are fun to learn.  But an adjustment to
>the fundamental algorithm (if it is possible) is often dominatingly better than
>that.
>
>So, my steps to make something faster are like this:
>1.  Profile to find the slow spots.
>2.  Examine and understand the algorithms in the slow places
>3.  Look for a better algorithm
>4.  If a better algorithm exists, try it
>5.  If a better algorithm does not exist, try to improve the existing algorithm
>6.  If still a slow spot, resort to tweaky sorts of things and inline assembly.
>
>One idea that is often helpful is to precompute as much as possible, and store
>the results in a compact lookup table.  Then the complex calculation becomes a
>simple lookup.

I know it.

The point is that the better algorithm that I have is to write similiar
functions to the functions that I have and when I write similiar functions I
also think of optimizing the previous functions.

Today I have not a function to generate only captures and I need to do it but it
leads me to think again about my move generator and I find ideas that can do it
faster.

I do not do the things that will help most to the speed of my program
because they may take time and I prefer first to see what I can improve
relatively fast.

I also think that evaluation of endgames is more important but I like more doing
Movei faster because it is easier to test for bugs(if I get the same number of
nodes then I know that I probably have no bugs).

Uri



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