Author: Robert Hyatt
Date: 20:06:55 04/16/01
Go up one level in this thread
On April 16, 2001 at 22:53:34, Eugene Nalimov wrote: >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... > >Visual C allows you to declare the global variable as "thread-specific", i.e. >each thread will have its own copy of the variable. Compiler generates special >code to access such a variables. > >Eugene Many machines have a variant of this. On the Cray, we had global variables in FORTRAN via a "common" statement. They added "task common" which were global but thread-specific. I do the same thing via pointers in normal C. A thread-specific (local) pointer that points to a global area that is allocated to a specific thread for its exclusive use... But any such thing causes syntacical changes and lots of debugging...
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