naromero

/* * Driver for demonstrating MPI_Reduce_scatter performance problems on two  * racks of BG/P. * * Please contact Jack Poulson at <jack.poulson@gmail.com> for more information. */#include "mpi.h"#include "mpix.h"#include <stdio.h>const int num_tests = 20;int MPIX_Get_last_algorithm(MPI_Comm comm, int *lastalgorithm);/* Test from 100 doubles to 3000 doubles contributions in multiples of 100 */voidTestReduceScatter( MPI_Comm comm, char* comm_name ){    int num_doubles;    int comm_size, comm_rank, world_rank;    int* rcs;    double* send_buffer;    double* recv_buffer;    int result;    /* Extract the communicator properties and our world rank */    MPI_Comm_size( comm, &comm_size );    MPI_Comm_rank( comm, &comm_rank );    MPI_Comm_rank( MPI_COMM_WORLD, &world_rank );    rcs = (int*)malloc(comm_size*sizeof(int));    /* Loop over local contribution sizes */    if( world_rank == 0 )    {        printf("Testing over %s\n", comm_name);        printf("Local contribution   Megabits/second   Algorithm\n");        printf("------------------------------------------------\n");    }    for( num_doubles=100; num_doubles<=2000; num_doubles+=100 )    {        int test;        int rank;        double megabits, megabits_per_second;        double start_time, end_time, average_time;        int last;        megabits = num_doubles*comm_size*sizeof(double)*8/1.e6;        for( rank=0; rank<comm_size; ++rank )            rcs[rank] = num_doubles;        send_buffer = (double*)malloc(num_doubles*comm_size*sizeof(double));        recv_buffer = (double*)malloc(num_doubles*sizeof(double));        start_time = MPI_Wtime();        for( test=0; test<num_tests; ++test )        {            MPI_Reduce_scatter            ( send_buffer, recv_buffer, rcs, MPI_DOUBLE, MPI_SUM, comm );        }        end_time = MPI_Wtime();        average_time = (end_time-start_time)/num_tests;        megabits_per_second = megabits/average_time;        MPIX_Get_last_algorithm(comm, &last);        if( world_rank == 0 )            printf("%8d doubles     %8lf     %8ld \n", num_doubles, megabits_per_second, last);        free( send_buffer );        free( recv_buffer );    }    if( world_rank == 0 )        printf("\n");    free( rcs );}intmain( int argc, char* argv[] ){    int XYZT_size, XYZT_rank, XY_size, XY_rank, ZT_size, ZT_rank;    int remainingDimensions[4];    MPI_Comm XYZT_comm, XY_comm, ZT_comm;    MPI_Init( &argc, &argv );     MPIX_Cart_comm_create( &XYZT_comm );     MPI_Comm_size( XYZT_comm, &XYZT_size );    MPI_Comm_rank( XYZT_comm, &XYZT_rank );    /* Create the XY subcommunicator */    remainingDimensions[0] = 0;    remainingDimensions[1] = 0;    remainingDimensions[2] = 1; /* keep Y */    remainingDimensions[3] = 1; /* keep X */    MPI_Cart_sub( XYZT_comm, remainingDimensions, &XY_comm );    MPI_Comm_rank( XY_comm, &XY_rank );    MPI_Comm_size( XY_comm, &XY_size );    /* Create the ZT subcommunicator */    remainingDimensions[0] = 1; /* keep T */    remainingDimensions[1] = 1; /* keep Z */    remainingDimensions[2] = 0;    remainingDimensions[3] = 0;    MPI_Cart_sub( XYZT_comm, remainingDimensions, &ZT_comm );    MPI_Comm_rank( ZT_comm, &ZT_rank );    MPI_Comm_size( ZT_comm, &ZT_size );    if( XYZT_rank == 0 )    {        printf("Communicator properties:  \n");        printf("--------------------------\n");        printf("(X,Y) size:     %d\n", XY_size);        printf("(Z,T) size:     %d\n", ZT_size);        printf("(X,Y,Z,T) size: %d\n", XYZT_size);        printf("\n");    }    TestReduceScatter( XY_comm, "(X,Y)" );    TestReduceScatter( ZT_comm, "(Z,T)" );    TestReduceScatter( XYZT_comm, "(X,Y,Z,T)" );    return 0;}