/* nag_omp_set_nested (x06agc) Example Program.
*
* Copyright 2024 Numerical Algorithms Group.
*
* Mark 30.1, 2024.
*/
#include <nag.h>
#include <stdio.h>
int main(void) {
/* Scalars */
Integer exit_status = 0;
Integer nesting, nesting_set, num_inner, num_outer, total;
/* Nag Types */
NagError fail;
INIT_FAIL(fail);
/* Output preamble */
printf("nag_omp_set_nested (x06agc)");
printf(" Example Program Results\n\n");
nesting_set = 1;
/*
* nag_omp_set_nested (x06agc).
* Enable the nesting of OpenMP parallel regions
*/
nag_omp_set_nested(nesting_set);
num_inner = 3;
num_outer = 5;
/*
* nag_omp_set_num_threads (x06aac).
* Set the number of threads for an outer parallel region
*/
nag_omp_set_num_threads(num_outer, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_omp_set_num_threads (x06aac).\n%s\n", fail.message);
fflush(stdout);
exit_status = 1;
goto END;
}
/*
* Spawn an OpenMP parallel region and have the master thread check whether
* nesting of parallel regions has been enabled
*/
total = 0;
#ifdef _OPENMP
#pragma omp parallel shared(num_inner,total) private(fail,nesting) \
reduction(+:exit_status) default(none)
#endif
{
INIT_FAIL(fail);
/*
* nag_omp_get_nested (x06ahc).
* Test whether nesting of parallel regions has been enabled
*/
nesting = nag_omp_get_nested();
#ifdef _OPENMP
#pragma omp master
#endif
{ printf("\n%s %11" NAG_IFMT " \n\n", "Nesting enabled: ", nesting); }
/*
* Set the number of threads for an inner parallel region
*/
nag_omp_set_num_threads(num_inner, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_omp_set_num_threads (x06aac).\n%s\n",
fail.message);
exit_status++;
} else {
/*
* Spawn a nested parallel region and add up the total number of threads
* in all teams
*/
#ifdef _OPENMP
#pragma omp parallel shared(total) default(none)
#endif
{
#ifdef _OPENMP
#pragma omp atomic
#endif
total++;
}
}
}
fflush(stdout);
if (exit_status == 0) {
printf("\n%s %11" NAG_IFMT " \n\n", "Total number of threads requested ",
num_outer * num_inner);
printf("\n%s %11" NAG_IFMT " \n\n",
"Total number of threads from sum: ", total);
fflush(stdout);
}
END:
return exit_status;
}