Author: Vincent Diepeveen
Date: 05:00:27 04/17/01
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On April 16, 2001 at 22:07:10, Robert Hyatt wrote: >On April 16, 2001 at 18:15:52, Dieter Buerssner wrote: > >>In a different discussion, Vincent wrote the following: >> >>>It is not difficult to implement the form of parallellism as used by >>>Rudolf. Invented by a frenchman who couldn't spell a word english and >>>who wrote an impossible article for JICCA (did anyone proofread it at >>>the time as i'm pretty sure they didn't get his parallel idea?). >>> >>>At the time when i read the article i was pathetically laughing about it >>>actually as i also didn't get the idea of the frenchman. But it appears >>>everyone who can make a chessprogram work under win2000 can also get >>>within an afternoon his program parallel to work. Then some debugging >>>and a day later it works cool. >> >>I'd be very interested in this algorithm, that can be implemented at an >>afternoon :-) >> >>Could you point elaborate on this. >> >>BTW. In Paderborn, Roland Pfister also told me, that he knows this from Rudolf >>Huber, and he even started to explain it to me. Somhow, we (or me) got >>distracted, and I cannot remember the essential things. >> >>What I remember is, that the time consuming work, of making your >>search/evaluation routines free from all those global variables is not needed. >> >>Regards, >>Dieter > > >Global variables will _always_ be a problem. Unless you avoid threads >altogether and use separate processes. But then you incur other penalties >you have to solve... Multiprocessing is faster anyway of course as multithreading as i do not need to read a stupid pointer. Arrays which are only read and not modified one can put in shared memory and read from there without penalties. The penalty for multithreading is, when using ansi-c conventions, way bigger as for multiprocessing. Multiprocessing is more than ok. Obviously it's not always so easy to get it to work, because of different causes - allocating shared memory in linux isn't simple - windows NT server/tuple server versions have the bad habit to always swap away shared memory to the cache when the allocated memory size is huge. - to share memory in NT in such a way that programs have the same virtual adress space is not evident, as there are 2 functions which one can use and one of them is not going to work for you. Don't need to mention that by accident i picked the wrong function initially :) Of course all the above problems are solvable
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