Basic HTML version of Foils prepared 13 February 2000

Foil 14 Distributed Memory Machines -- Notes

From Methodology of Computational Science CPS615 Computational Science -- Spring Semester 2000. by Geoffrey C. Fox
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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