Scripted HTML version of Foils prepared 11 November 1996

Foil 13 Examples of MPI_ALLTOALL

From CPS615-Completion of MPI foilset and Application to Jacobi Iteration in 2D Delivered Lectures of CPS615 Basic Simulation Track for Computational Science -- 7 November 96. by Geoffrey C. Fox *
Secs 241.9
All to All Communication with i'th location in j'th processor being sent to j'th location in i'th processor
Processor 0 1 2 3
Start (a0,a1,a2,a3) (b0,b1,b2,b3) (c0,c1,c2,c3) (d0,d1,d2,d3)
After (a0,b0,c0,d0) (a1,b1,c1,d1) (a2,b2,c2,d2) (a3,b3,c3,d3
There are extensions MPI_ALLTOALLV to handle case where data stored in noncontiguous fashion in each processor and when each processor sends different amounts of data to other processors
Many MPI routines have such "vector" extensions

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