Author: Robert Hyatt
Date: 06:38:43 12/08/03
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On December 08, 2003 at 04:57:58, Sven Reichard wrote: >On December 07, 2003 at 23:00:10, Robert Hyatt wrote: > >>On December 07, 2003 at 20:40:51, Sean Mintz wrote: >> >>>Discussions about running chess programs efficiently on clusters have been going >>>on here for as long as I can remember. With the recent (impressive!) work by >>>Hyatt and Nalimov, I wonder if this brings us any closer towards efficient >>>searches by clusters. Although there are many major differences left, NUMA >>>seems to me much closer to clusters than SMP. Are we getting closer, or are the >>>differences still to great/many? >>> >>>Sean Mintz >> >> >>Still a long way apart. NUMA is _still_ shared memory. Clusters are still >>message-passing. Handling NUMA is just a special-case of shared memory stuff >>that simply offers more performance if done right... > > >A while ago I read about an algorithm specifically geared towards clusters; it >had some cryptachrostic name like APHID or something like that... Anyway, it >didn't depend on shared memory, just on low bandwidth message passing. Correct... > >The basic idea was the following: The master process searches to a shallow depth >(say, 4 ply) and distributes the encountered nodes to the slaves. Each slave >investigates its nodes independently, feeding back its findings to the master. >The main advantage was that if one slave has finished all work on a given ply, >it can immediately continue with the next ply, without waiting for the other >slaves to finish. > >Of course there are still many issues to resolve, such as efficient distribution >of the subtrees and providing reasonably search bounds to the slaves. Also, it >is not clear how this scales to large clusters. > >Does anybody have practical experience with this approach? > >Sven. Not me, when you say "practical experience". I've done _lots_ of distributed computing, but not chess-related yet. But it won't be long.
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