Author: Robert Hyatt
Date: 06:00:40 05/27/98
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On May 27, 1998 at 04:11:12, Jouni Uski wrote: >Bob please explain, what's the situation with multiprosessor Crafty - >I haven't seen any details yet! Which kind of hardware You have, >achieved NPS, which kind of operating system etc... >Thanks Jouni First, It is running under SMP linux on my machine, but it also runs well on Solaris, Digital unix (alpha), and Windows NT. It should compile and run on any unix that supports posix threads, which most do... I'm running on an ALR quad-6 revolution with four pentium-pro 200mhz processors and 512mb of RAM (although I usually run with hash=24M still). The NPS values are basically quadrupuled, although, in reality, using all 4 processors the program currently is running between 2-3.5 times faster depending on the position. It seems to be averaging around 3x faster at present, although lots of work is left to do. "Moron" on ICC is running SMP crafty on a dual pentium-II/333mhz machine (also using linux) and the two processor version is really quite efficient. We also have a couple of NT guys running on various servers... The only thing wrong with the 4X NPS is that, in reality, there is search overhead to consider as well. The tree grows as the number of processors goes up, due to the inherent sequential nature of alpha/beta. Typically, no matter how many processors are added, the tree still gets larger. The overhead seems to be between 25% and 35% in typical cases... although it can be way less at times, and occasionally can be much worse... Let me know what specific questions you have... if you'd like to see it run, visit ICC, as it is playing there in 4-processor mode all the time. Bob
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