Author: Robert Hyatt
Date: 19:41:50 01/29/99
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On January 29, 1999 at 11:52:05, KarinsDad wrote: >On January 29, 1999 at 10:45:51, Albrecht Heeffer wrote: > >[snip] >> >>After the tournament I burned a CD-R with the complete directory image >>of all sources, executables and log files. The version on the website >>'bionic41.exe' is ftp'd directly from the CD onto the web site. It _is_ >>the same version as used during both weekends of the tournament, I >>can assure you. The SMP code must be very indeterministic if we can't >>reproduce the moves somehow. >> >>Albrecht Heeffer > >Actually, it may be extremely deterministic, just not deterministic with the >environments you are using. To reproduce the results, you may need to run on the >exact same hardware and have the "opposing player" respond on each move within >the exact same time frame. I can guarantee you it is highly non-deterministic, and it was designed that way for performance. Practically no places where one processor is 'waiting'. No 'synchronization' points, etc. The hash table causes huge non-determinism. random processor timing resulting in different split points every time you run the same position. It is a debugging nightmare, but a barn-burner in terms of performance... > >The number of variables in a chess program is huge. The number of variables in >an SMP version of a chess program is larger. I realize that when testing most >non-SMP versions of programs, that the program will often come up with the exact >same move within 1 minute as it does in 5 minutes (and hence Bruce's test >suite), however, an SMP version of a program may have different results. > >Have you examined the moves that are not corresponding with the tournament >results to see if the move considered at a lesser time during the tournament is >different than the actual one made and identical to the one made in the test? I >am not saying that this is where the problem lies, it's just a possibility for >some of the mis-matches. > >KarinsDad
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