Basic HTML version of Foils prepared August 7 98

Foil 20 Implementation of DISTRIBUTE

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


Allocate enough memory on each processor for its section of each distributed array
  • Distributed memory: 1 malloc per processor or shrink bounds
  • Shared memory: 1 shared area, with usage divided
Adjust indexing
  • Distributed memory: translate global indices ¤ local numbering
  • Shared memory: permute elements, keep each processor's together
Adjust loops (including implicit loops)
  • Pick a reference in the loop (e.g. A(J+1))
  • Each processor executes iterations so that reference is local (e.g. lb-1:ub-1)
Handle nonlocal data
  • Distributed memory: allocate buffer space, SEND/RECV needed data
  • Shared memory: access data directly, or allocate & make local copies



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