Basic HTML version of Foils prepared August 7 98

Foil 43 Hints for Using Data Mapping

From DoD HPF Training -- 4. HPF Data Mapping Facilities DoD Training and Others -- 1995-98. by Chuck Koelbel -- Rice University


ALIGN data based on physical domains
  • Arrays with the same domain should be aligned
  • Arrays not physically connected should not
DISTRIBUTE based on parallelism
  • Optimal performance comes from parallel operations on a distributed axis
Pick distribution pattern based on communications
  • BLOCK generally good for local stencils and fully-filled arrays
  • CYCLIC and CYCLIC(K) generally good for load balancing and triangular loops
  • Conflicts require compromises, remapping, complex compilers, or new algorithms
REALIGN with care; REDISTRIBUTE with extreme care
  • Computation performed must outweigh communication for the remapping



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