sched_setscheduler
int sched_setscheduler(pid_t, int, const struct sched_param *);
if (sched_setscheduler(0, new_policy, ¶m) == -1) {
(void) sched_setscheduler(0, orig_policy, &orig_param);
if (sched_setscheduler(0, SCHED_FX, ¶m) == -1) {
(void) sched_setscheduler(0, orig_policy, &orig_param);