Basic HTML version of Foils prepared August 7 98

Foil 20 Implementation of HPF 2 Parallel Features

From DoD HPF Training -- 6. HPF2 DoD Training and Others -- 1995-98. by Chuck Koelbel -- Rice University


1 All new features represent useful information to the compiler
  • They do not change the meaning of the program if properly used
2 REDUCTION
  • Choose an efficient order of evaluation for the reduction tree
  • For scalar reductions, keep a local sum on each node and have a global combining phase at the end
    • Alternate implementation: critical region
  • For vector reductions, use same algorithm as XXX_SCATTER
3 ON HOME
  • Base the loop partitioning on the HOME expression
  • Invert subscripting function to derive loop bounds
  • Does not affect where communication/synchronization can be placed, but may change what must be communicated
  • Warning: You can outsmart the compiler this way‹to your detriment

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