Basic HTML version of Foils prepared 19 September 98

Foil 47 More Examples of Collective Communication/Computation

From MPI Message Passing Interface Computational Science for Simulations -- Fall Semester 1998. by Geoffrey C. Fox, Nancy McCracken
Four Processors where each has a send buffer of size 2
  • 0 1 2 3 Processors
  • (2,4) (5,7) (0,3) (6,2) Initial Send Buffers
  • MPI_SENDRECV with 0,1 and 2,3 paired
  • (5,7) (2,4) (6,2) (0,3) Resultant Buffers
  • MPI_GATHER with root=0
  • (2,4,5,7,0,3,6,2) (_,_) (_,_) (_,_) Resultant Buffers
  • Now take four Processors where only rank=0 has send buffer
  • (2,4,5,7,0,3,6,2) (_,_) (_,_) (_,_) Initial send Buffers
  • MPI_SCATTER with root=0
  • (2,4) (5,7) (0,3) (6,2) Resultant Buffers

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