Basic HTML version of Foils prepared Oct 26,97

Foil 31 Parallel Algorithm in Fast Multipole I

From Master Set of Foils for GEM Computational Science Presentation GEM Workshop Santa Fe -- October 24-25 1997. by Geoffrey C. Fox


Parallelism is clear -- update particles in parallel but what about communication?
It requires a thoughtful algorithm but can efficiently fetch information needed.
  • Fetch all the information needed by ANY particle in a given processor as multipole approach implies that particles tend to need same long range components if nearby
  • call this "locally essential" data
  • cf. O(N) multipole-multipole approach
Effectively top of tree replicated in all processors and tey just differ near bottom which is expanded in a way that depends on where processor is



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