Author: Uri Blass
Date: 07:18:14 07/09/04
Go up one level in this thread
On July 09, 2004 at 09:53:02, Daniel Clausen wrote: >On July 09, 2004 at 09:47:36, Tord Romstad wrote: > >>On July 09, 2004 at 09:13:31, Robert Hyatt wrote: >> >>>On July 09, 2004 at 08:38:31, Tord Romstad wrote: >>> >>>>I am currently writing a chess engine. Parallel search is not among my main >>>>interests at the moment, but it is not entirely impossible that I will give it >>>>a try some time in the future. >>>> >>>>In order to keep everything as flexible as possible, I would like to design >>>>my algorithms and data structures in such a way that adding parallel search >>>>at a later stage is feasible. I understand that I should remove most of my >>>>global variables and replace them with huge structs containing the same data, >>>>and use one such struct for each thread. Is there anything else which is >>>>important to keep in mind? >>>> >>>>Tord >>> >>> >>>That's the main issue assuming you are going to use lightweight processes >>>(threads) which I believe is the best approach. >> >>Yes, threads is what I intend to use. >> >>>The most thread-specific data >>>you have, which means less global data, will help performance (modified global >>>data is not cache-friendly on a SMP box) and simplify testing (since modified >>>global data requires atomic locks to avoid interleaved update problems). >> >>But as far as I can see, I would be forced to pass an extra pointer to most >>of the chess-related functions (search(), evaluate(), generate_moves(), >>make_move() etc.). A bit ugly, but I suppose I could live with that. > >What do you mean with ugly here? > >To me, functions which work on exactly the arguments they get and maybe return >something are much clearer than functions which work on data that is cluttered >all over the place. :) > >Sargon The ugly thing is that if I plan to add function call then I need to add a lot of parameters. Another problem is that if later I want to change the function to include one more parameter then I need also to change all the places when I called the function. I think that you are right that it may be clearer to understand things and it is more important. Unfortunately I wanted to do some changes as fast as possible and by adding global varaibles I saved time by not giving them as parameters to many functions and I did not need to think exactly which varaibles are going to be changed by every function. The cost was a code that is badly written and later it is harder to detect bugs in the code or think about changing things. Uri
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