Author: Bob Durrett
Date: 07:11:34 09/14/03
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On September 14, 2003 at 09:28:07, Uri Blass wrote: >I know that usually top programs do not evaluate a lot of special cases about >endgames like situation of theoretical draw of KRPPP vs KRPP when the pawns are >in the same side > >My question is if except having more important things to do there is a speed >reason for programmers not to have big code for rare cases when calculating if >the rare cases happen is cheap but calculating the evaluation is not cheap? > >In the relevant example you can assume that >checking if a position is KRPPP vs KRPP is cheap but calculating if you can >evaluate it as a draw position is not cheap. > >Uri How much of a chess engine's code gets loaded into RAM? If not much or any, then it may be a speed hit to have to keep going to the hard drive to get needed blocks of code. My computer has 2 GB RAM but I typically allocate much of it to a Hash table. Perhaps there is some sort of tradeoff between hash table size and RAM remaining for the engine's other uses. I also do not know how much of the RAM is used to store temporary data [other than in hash tables] and how much is used to temporarily house engine code. Perhaps these factors vary from one engine to another or from one programmer to the next. I have always thought that, with the huge hard disks we have nowadays, the total number of lines of code is unimportant. Not being a professional computer programmer, I assume one brings into RAM only the code one is going to be using in the near term and then use the code there to minimize trips to the hard drive. I envision special-purpose blocks of code being brought into RAM only when needed and written over when no longer needed. That has been my perception. Awhile back, I asked about the feasibility of loading blocks of engine code into one or more of the microprocessor's on-die memory elements. The idea is that the time needed to go get needed code would be very small in that case. No one said that would be impractical if the on-die memory elements were large enough. It would just be difficult for the programmer since he/she does not have complete control over what happens on-die. Bob D.
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