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56 lines
1.4 KiB
56 lines
1.4 KiB
#include "mpi.h"
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#include <stdio.h>
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#define SIZE 16
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#define UP 0
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#define DOWN 1
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#define LEFT 2
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#define RIGHT 3
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int main(argc,argv)
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int argc;
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char *argv[]; {
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int numtasks, rank, source, dest, outbuf, i, tag=1,
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inbuf[4]={MPI_PROC_NULL,MPI_PROC_NULL,MPI_PROC_NULL,MPI_PROC_NULL,},
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nbrs[4], dims[2]={4,4},
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periods[2]={0,0}, reorder=0, coords[2];
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MPI_Request reqs[8];
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MPI_Status stats[8];
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MPI_Comm cartcomm;
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MPI_Init(&argc,&argv);
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MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
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if (numtasks == SIZE) {
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MPI_Cart_create(MPI_COMM_WORLD, 2, dims, periods, reorder, &cartcomm);
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MPI_Comm_rank(cartcomm, &rank);
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MPI_Cart_coords(cartcomm, rank, 2, coords);
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MPI_Cart_shift(cartcomm, 0, 1, &nbrs[UP], &nbrs[DOWN]);
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MPI_Cart_shift(cartcomm, 1, 1, &nbrs[LEFT], &nbrs[RIGHT]);
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outbuf = rank;
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for (i=0; i<4; i++) {
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dest = nbrs[i];
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source = nbrs[i];
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MPI_Isend(&outbuf, 1, MPI_INT, dest, tag,
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MPI_COMM_WORLD, &reqs[i]);
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MPI_Irecv(&inbuf[i], 1, MPI_INT, source, tag,
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MPI_COMM_WORLD, &reqs[i+4]);
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}
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MPI_Waitall(8, reqs, stats);
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printf("rank= %d coords= %d %d neighbors(u,d,l,r)= %d %d %d %d\n",
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rank,coords[0],coords[1],nbrs[UP],nbrs[DOWN],nbrs[LEFT],
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nbrs[RIGHT]);
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printf("rank= %d inbuf(u,d,l,r)= %d %d %d %d\n",
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rank,inbuf[UP],inbuf[DOWN],inbuf[LEFT],inbuf[RIGHT]);
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}
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else
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printf("Must specify %d processors. Terminating.\n",SIZE);
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MPI_Finalize();
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}
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