Author: Robert Hyatt
Date: 11:37:39 10/08/02
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On October 08, 2002 at 14:29:02, Rex wrote: >I agree that dual or more processors are faster. My question is the effeciency >of search may be decrease. The weight of a given move may be decreased when its >way down the tree. The differences of move weight gets less efficiant when the >tree search gets deeper and deeper. Calculating what would be the best move >based on score may not be the best move at all. Figuring this calculation deep >in the search tree is probably imposible until that particular move arrives 1 to >2 moves deep. Then it may be too late. By faster, I don't mean "faster NPS only". I mean that if it takes one 1ghz processor 3 minutes to search to depth X, then the two 1ghz machine should take significantly less than 3 minutes to reach that same depth X. For Crafty, the rough number is about 1.7. IE if it takes 3 minutes for one cpu, then it will take around 1.7 minutes to do the same search using two cpus. For Crafty, the NPS will be closer to 2x faster using two cpus, but the "search efficiency" you mentioned drops the overall performance gain down to 1.7X or so... (again, this is an _average_ number, for those that like to question it. Some positions speed up more than 2.0 times faster, other speed up significanly less than 2.0 times faster. The overall _average_ seems to hover around 1.7 for Crafty. YMMV on other programs or on different hardware.)
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