Author: Robert Hyatt
Date: 11:00:50 01/06/04
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On January 06, 2004 at 13:36:19, Anthony Cozzie wrote: >One of the things that I'm very curious about in the DTS paper is the copying >that goes on. If you are on a shared memory machine, why do you need to copy >everything? I don't copy everything, just the "current tree state". I have to do that so that two threads can search, update their tree state independently, and finally return me a score and PV from what they did. > >How many nodes does crafty do per split? Very hard to say. Sometimes it only splits a total of 100 times in 5 minute searches. Sometimes 5000 times in 5 minute searches (more rare). And again, that depends on the number of processors, since that controls how many different tree segments are being searched in parallel. 2 processors might not split very much at all, while 16 will get pretty busy at times. :) But for the copy question, think about a chess position and you want two people to search it in parallel. You give them each a board with the current position, and then as they ask, you tell them the next move to search. If they were sharing one board, it would be chaos and they would interfere with each other. > >anthony
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