gather2.c

mpi并行计算的c++代码 可用vc或gcc编译通过 可以用来搭建并行计算试验环境

/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
 *
 *  (C) 2003 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */

#include "mpi.h"
#include "mpitest.h"
#include <stdlib.h>
#include <stdio.h>

/* Gather data from a vector to contiguous.  Use IN_PLACE */

int main( int argc, char **argv )
{
    MPI_Datatype vec;
    double *vecin, *vecout;
    MPI_Comm comm;
    int    count, minsize = 2;
    int    root, i, n, stride, errs = 0;
    int    rank, size;

    MTest_Init( &argc, &argv );

    while (MTestGetIntracommGeneral( &comm, minsize, 1 )) {
	if (comm == MPI_COMM_NULL) continue;
	/* Determine the sender and receiver */
	MPI_Comm_rank( comm, &rank );
	MPI_Comm_size( comm, &size );
	
	for (root=0; root<size; root++) {
	    for (count = 1; count < 65000; count = count * 2) {
		n = 12;
		stride = 10;
		vecin = (double *)malloc( n * stride * size * sizeof(double) );
		vecout = (double *)malloc( size * n * sizeof(double) );
		
		MPI_Type_vector( n, 1, stride, MPI_DOUBLE, &vec );
		MPI_Type_commit( &vec );
		
		for (i=0; i<n*stride; i++) vecin[i] =-2;
		for (i=0; i<n; i++) vecin[i*stride] = rank * n + i;
		
		if (rank == root) {
		    for (i=0; i<n; i++) {
			vecout[rank*n+i] = rank*n+i;
		    }
		    MPI_Gather( MPI_IN_PLACE, -1, MPI_DATATYPE_NULL, 
				vecout, n, MPI_DOUBLE, root, comm );
		}
		else {
		    MPI_Gather( vecin, 1, vec, NULL, -1, MPI_DATATYPE_NULL, 
				root, comm );
		}
		if (rank == root) {
		    for (i=0; i<n*size; i++) {
			if (vecout[i] != i) {
			    errs++;
			    if (errs < 10) {
				fprintf( stderr, "vecout[%d]=%d\n",
					 i, (int)vecout[i] );
			    }
			}
		    }
		}
		MPI_Type_free( &vec );
		free( vecin );
		free( vecout );
	    }
	}
	MTestFreeComm( &comm );
    }

    /* do a zero length gather */
    MPI_Comm_rank( MPI_COMM_WORLD, &rank );
    if ( rank == 0 ) {
	MPI_Gather( MPI_IN_PLACE, -1, MPI_DATATYPE_NULL, NULL, 0, MPI_BYTE, 0, MPI_COMM_WORLD );
    } else {
	MPI_Gather( NULL, 0, MPI_BYTE, NULL, 0, MPI_BYTE, 0, MPI_COMM_WORLD );
    }

    MTest_Finalize( errs );
    MPI_Finalize();
    return 0;
}