mirror of https://github.com/QMCPACK/qmcpack.git
59 lines
1.6 KiB
C
59 lines
1.6 KiB
C
#include "mpi.h"
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#include <stdlib.h>
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#include <stdio.h>
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/* Gather data from a vector to contiguous */
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int main( int argc, char **argv )
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{
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MPI_Datatype vec;
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MPI_Comm comm;
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double *vecin, *vecout;
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int minsize = 2, count;
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int root, i, n, stride, errs = 0;
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int rank, size;
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MPI_Init( &argc, &argv );
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comm = MPI_COMM_WORLD;
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/* Determine the sender and receiver */
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MPI_Comm_rank( comm, &rank );
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MPI_Comm_size( comm, &size );
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for (root=0; root<size; root++) {
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for (count = 1; count < 65000; count = count * 2) {
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n = 12;
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stride = 10;
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vecin = (double *)malloc( n * stride * size * sizeof(double) );
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vecout = (double *)malloc( size * n * sizeof(double) );
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MPI_Type_vector( n, 1, stride, MPI_DOUBLE, &vec );
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MPI_Type_commit( &vec );
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for (i=0; i<n*stride; i++) vecin[i] =-2;
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for (i=0; i<n; i++) vecin[i*stride] = rank * n + i;
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MPI_Gather( vecin, 1, vec, vecout, n, MPI_DOUBLE, root, comm );
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if (rank == root) {
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for (i=0; i<n*size; i++) {
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if (vecout[i] != i) {
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errs++;
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if (errs < 10) {
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fprintf( stderr, "vecout[%d]=%d\n", i, (int)vecout[i] );fflush(stderr);
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}
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}
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}
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}
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MPI_Type_free( &vec );
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free( vecin );
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free( vecout );
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}
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}
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/* do a zero length gather */
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MPI_Gather( NULL, 0, MPI_BYTE, NULL, 0, MPI_BYTE, 0, MPI_COMM_WORLD );
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MPI_Finalize();
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return 0;
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}
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