int sched_setparam(pid_t pid, const struct sched_param *p);
int sched_getparam(pid_t pid, struct sched_param *p);
sched_setparam sets the scheduling parameters associated with the scheduling policy for the process identified by pid. If pid is zero, then the parameters of the current process are set. The interpretation of the parameter p depends on the selected policy. Currently, the following three scheduling policies are supported under Linux: SCHED_FIFO, SCHED_RR, and SCHED_OTHER.
sched_getparam retrieves the scheduling parameters for the process identified by pid. If pid is zero, then the parameters of the current process are retrieved.
sched_setparam checks the validity of p for the scheduling policy of the process. The parameter p- must lie within the range given by sched_get_priority_min and sched_get_priority_max.
The process whose ID is pid could not be found.
The calling process does not have appropriate privileges. The process calling sched_setparam needs an effective uid equal to the euid or uid of the process identified by pid, or it must be a superuser process.
sched_setscheduler(2), sched_getscheduler(2), sched_get_priority_max(2), sched_get_priority_min(2), nice(2), setpriority(2), getpriority(2),
sched_setscheduler(2) has a description of the Linux scheduling scheme.