Author: Vincent Diepeveen
Date: 15:05:06 09/20/00
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On September 19, 2000 at 11:05:01, Frank Quisinsky wrote: >On September 19, 2000 at 10:16:19, Robert Hyatt wrote: >A questions to Crafty: >I see that Crafty 17.13 is not faster then Crafty 17.11 but the new SMP version >is faster. >At the moment is the dual technic factor 1.8. Do you think that factor 1.9 or >1.95 is possible ? Diep gets 2.0 at 2 minutes a move , IF YOU HAVE AT LEAST 150MB HASH. Note that diep is a slow searcher AND using multiprocessing AND each process is SMP, where all parallel programs i know aren't SMP except cray blitz. Not SMP: the process having the recursions can't abort when the last moves searched are done by a different process. Apart from that the chance that the first move gives a cutoff in a 'beta' node is quite small in diep compared to most programs (yet it's using very nodes a ply compared to other programs despite that it's not forward pruning yet). At levels of 30 minutes a move at a fast PIIIdual i see average speedup of way over 2.0, more like 3.0. You can theoretical be much much faster as 2.0. consider this. Suppose you split in a position x. Now suppose that process 1 searches a move A, and process 2 searches move B. Now move A is a long and heavy search, but process 2 quickly gets a cutoff for move B. So single cpu you would be hours busy with move A, but now you get a quick cutoff for move B. >I have interest to get more information why is not more then factor 1.8 >possible. I think a very interesting message for my News Ticker because more and >more persons have interest to buy a dual system an I think this is a interesting >question about SMP. Where diep's speedup dual is great, i'm lacking a lot of tests at 4 processors for speedup. Yet it seems that getting 4.0 out of 4 processors is nearly impossible (some forward pruning versions of diep could achieve this but the versions without forward pruning did much worse). Dual however is getting a great boost when at the newyear we will see the first thunderbirds dual at ABIT dual motherboards. I can't wait to get one of those! >See here (little zip file, Crafty bench results on dual and single PIII): >http://amateurschach.in-trier.de/schach/download/sonstige/crafty_bench2.zip >Frank
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