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#include "stdio.h"
#include "mpi.h"
const int size = 1000;
float a[size][size];
float b[size][size];
float c[size][size];
void multiply(int istart, int iend)
{
for (int i = istart; i <= iend; ++i) {
for (int j = 0; j < size; ++j) {
for (int k = 0; k < size; ++k) {
c[i][j] += a[i][k] * b[k][j];
}
}
}
}
int main(int argc, char* argv[])
{
int rank, nproc;
int istart, iend;
double start, end;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &nproc);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
// MPI_Barrier(MPI_COMM_WORLD);
// start = MPI_Wtime();
if (rank == 0) {
// Initialize buffers.
for (int i = 0; i < size; ++i) {
for (int j = 0; j < size; ++j) {
a[i][j] = (float)i + j;
b[i][j] = (float)i - j;
c[i][j] = 0.0f;
}
}
}
// Broadcast matrices to all workers.
MPI_Bcast(a, size*size, MPI_FLOAT, 0,MPI_COMM_WORLD);
MPI_Bcast(b, size*size, MPI_FLOAT, 0,MPI_COMM_WORLD);
MPI_Bcast(c, size*size, MPI_FLOAT, 0,MPI_COMM_WORLD);
// Partition work by i-for-loop.
istart = (size / nproc) * rank;
iend = (size / nproc) * (rank + 1) - 1;
// Compute matrix multiplication in [istart,iend]
// of i-for-loop.
// C <- C + A x B
multiply(istart, iend);
// Gather computed results.
MPI_Gather(c + (size/nproc*rank),
size*size/nproc,
MPI_FLOAT,
c + (size/nproc*rank),
size*size/nproc,
MPI_FLOAT,
0,
MPI_COMM_WORLD);
if (rank == 0) {
// Compute remaining multiplications
// when size % nproc > 0.
if (size % nproc > 0) {
multiply((size/nproc)*nproc, size-1);
}
}
// MPI_Barrier(MPI_COMM_WORLD);
// end = MPI_Wtime();
MPI_Finalize();
// if (rank == 0) { /* use time on master node */
// float msec_total = 0.0f;
// // Compute and print the performance
// float msec_per_matrix_mul = end-start;
// double flops_per_matrix_mul = 2.0 * (double)size * (double)size * (double)size;
// double giga_flops = (flops_per_matrix_mul * 1.0e-9f) / (msec_per_matrix_mul / 1000.0f);
// printf(
// "Performance= %.2f GFlop/s, Time= %.3f msec, Size= %.0f Ops\n",
// giga_flops,
// msec_per_matrix_mul,
// flops_per_matrix_mul);
// }
return 0;
}