Author: Uri Blass
Date: 12:50:11 02/19/03
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On February 19, 2003 at 15:38:53, Omid David Tabibi wrote: >On February 19, 2003 at 14:13:47, Uri Blass wrote: > >>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). > >But generating random numbers for hash key initializations might cause different >hash-table overwrites, and thus the total node count might slightly vary on the >same position and depth. I use fixed numbers for hash key initializations. Uri
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