Author: Robert Hyatt
Date: 19:09:26 09/11/02
Go up one level in this thread
On September 11, 2002 at 15:27:32, Dann Corbit wrote: >On September 11, 2002 at 15:10:49, Gian-Carlo Pascutto wrote: >[snip] >>>2. That there is definitely a linear improvement in new CPUs and 64 CPUs is >>>almost exactly twice as good as 32 CPUs. I think that is pretty astonishing, >>>and so however it is that communication happens between nodes should be tried >>>in other systems. >> >>It's a natural consequence of the fact that they have (almost) no >>synchronisation costs. > >Well, that's pretty interesting, isn't it? Can the same model be copied to >other algorithms? > >Surely they have to coordinate the information from the entire set of processors >somehow. The processors cannot be purely independent of one another or no >resolution would be reached. If a similar speedup could be obtained with >another scheme, it might be very valuable. > >Also, since they have done a test with 64 CPUs, I assume that they are using >some sort of NUMA architecture, since there are not many 64 CPU SMP systems >around. Hence, it might scale to stupendous CPU counts like the DoD >supercomputers with thousands of CPUs. If if the efficiency is 1%, if you have >10000 CPUs you will be at 100x the speed of a single CPU system. Maybe no other >system can match that. Two comments to _everybody_ fiddling with this thread. 1. The best serial algorithm is generally _not_ the best parallel algorithm. This has been shown over and over and over. The best parallel algorithm, by inverse thinking, is not necessarily the best serial algorithm either. Just because we use alpha/beta today doesn't mean we will be using it in 5 years on massively parallel machines. Quicksort is the best serial sort today. It isn't necessarily the best parallel sort for large numbers of processors. 2. Best-first is not thought much of today, because it has never worked well in the past. But that doesn't mean it _can't_ work well, just that nobody has really worked with it anywhere near as much as with Shannon's original minimax approach later augmented with the now infamous alpha/beta modification... I hesitate to throw rocks at people trying new ideas. Sometimes they waste tons of time, but _sometimes_ they find remarkable results...
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