why is nested OpenMP program is taking more time in executing?
My OpenMP program of matrix multiplication which consists of nesting of for loops is taking more execution time than the non-nested version of the parallel program. This is the block where I have used nested parallelisation.
pragma omp parallel
omp_set_nested(1);
#pragma omp parallel for
for(i=0;i<N;i++) {
#pragma omp parallel for
for(j=0;j<N;j++) {
C[i][j]=0.; // set initial value of resulting matrix C = 0
#pragma omp parallel for
for(m=0;m<N;m++) {
C[i][j]=A[i][m]*B[m][j]+C[i][j];
}
printf("C:i=%d j=%d %f n",i,j,C[i][j]);
}
}