Basic HTML version of Foils prepared 24 August 98

Foil 23 Distributed Memory Machines -- Notes

From Master Foilset for CPS615 Introduction -- Material from Culler and Koelbel Computational Science for Simulations -- Fall Semester 1998. by Geoffrey C. Fox, Nancy McCracken


Conceptually, the nCUBE CM-5 Paragon SP-2 Beowulf PC cluster are quite similar.
  • Bandwidth and latency of interconnects different
  • The network topology is a two-dimensional torus for Paragon, fat tree for CM-5, hypercube for nCUBE and Switch for SP-2
To program these machines:
  • Divide the problem to minimize number of messages while retaining parallelism
  • Convert all references to global structures into references to local pieces (explicit messages convert distant to local variables)
  • Optimization: Pack messages together to reduce fixed overhead (almost always needed)
  • Optimization: Carefully schedule messages (usually done by library)



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