Author: Robert Hyatt
Date: 07:53:19 05/03/04
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On May 03, 2004 at 10:19:46, Sune Fischer wrote: > >>I don't see any at 8. I don't personally have access to a 16-way box yet so I >>can't say anything there. But there is nothing that really makes null-move hurt >>parallel search... > >Couldn't it be, that nullmove hurts scalability in much the same way alpha-beta >"hurts" parallel search compared to minimax? I don't see how. It might make _some_ positions more unstable, and unstable positions hurt parallel search. But it also makes other positions more stable. > >I wouldn't be surprised if a more selective program was harder to parallelize in >general. I don't see why, unless you form the hypothesis of "forward pruning makes move ordering _worse_." That's the only wat this could happen... There are obviously "issues". Forward pruning tosses moves out. So at any node you will have fewer branches to search than in a normal (non-pruning) program. But if you don't require that all processors always work at the same node, this should not be a problem. IE Crafty searches endgames just as efficiently as it searches complex middlegames, from an SMP perspective... > >Perhaps at some point the benefit of nullmove is even lost to parallel >inefficiency and the disadvantages of nullmove begins to outweigh the savings? >That might make an interesting experiment :) > >Of course I don't know anything about it, only guessing. > >-S.
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