This problem has nothing to do with MPI. You are allocating a lot of memory on the stack. Try allocating the matrix with a bunch of malloc's instead. -- Pavan On 11/22/2012 12:35 PM US Central Time, Alejandro Allievi wrote:

Hi,

The following matrix multiplication code does not execute in my machine for MATRIX_ORDER greater than 400 or so, and I've got plenty of memory. Is there anything I need to tweak in MPI.h for this to work??

Thanks for any help.

Alejandro

#include <stdio.h> #include "mpi.h" /* for the Wtime() function only */

#define MATRIX_ORDER 400

typedef float MATRIX_T[MATRIX_ORDER][MATRIX_ORDER];

void serial_matrix_mult(MATRIX_T A, MATRIX_T B, MATRIX_T C, int n);

int main(int argc, char* argv[]) { MATRIX_T A; MATRIX_T B; MATRIX_T C; int i, j; double start, finish; int p, my_rank;

MPI_Init(&argc,&argv); MPI_Comm_size(MPI_COMM_WORLD, &p); MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

for (i = 0; i < MATRIX_ORDER; i++) /* initialize matrices */ for (j = 0; j < MATRIX_ORDER; j++) /* to an arbitrary value */ { A[i][j] = 5; B[i][j] = 5; }

start = MPI_Wtime(); serial_matrix_mult(A, B, C, MATRIX_ORDER); finish = MPI_Wtime();

printf("Elapsed time in seconds is %e\n", finish - start );

MPI_Finalize();

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-- Pavan Balaji http://www.mcs.anl.gov/~balaji