mpi_largest_sum.c

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

/*
Pra compilar execute mpicc mpi_largest_sum.c -o mpi_largest_sum
Pra rodar execute    mpirun -n 4 mpi_largest_sum
o parametro -n indica a quantidade de processadores, voce pode aumentar ou diminuir = )
*/

int main (int argc, char **argv) {
  int vector_size = 10;

  int sum = 0, global_sum;
  int i, rank, size;
  MPI_Status status;

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &size);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  int *vector_total = (int*)  calloc (10*size, sizeof(int));
  int *vector = (int*)  calloc (vector_size, sizeof(int));
  srand((unsigned)  time(NULL));

  if (rank == 0) {
      for(i = 0; i < 10 * size; i++){
      	vector_total[i] = rand() % 100;
    }
  }

  MPI_Scatter(vector_total, vector_size, MPI_INT, vector, vector_size, MPI_INT, 0, MPI_COMM_WORLD);

  for(i = 0; i < vector_size; i++){
  	  sum +=vector[i];
  }
  printf("soma de cada do vetor no processo[%d] = %d \n", rank, sum);
  MPI_Reduce(&sum, &global_sum, 1, MPI_INT, MPI_MAX, 0, MPI_COMM_WORLD);
  if (rank == 0){
  	printf("Maior valor: %d \n", global_sum);
  }

  MPI_Finalize();
  return 0;
}

Na linha 28, talvez fique melhor um MPI_Reduce(&sum_local, &vetor, vetor_size, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);. O que acha?

vou testar