play with SCHED_RR

sched_play.c

#include <stdio.h>
#include <errno.h>
#include <sched.h>
#include <sys/types.h>
#include <unistd.h>

void print_sched(){
  printf("PID=%d, SCHED=%d\n", getpid(), sched_getscheduler(getpid()));
}

int set_sched(int policy, int priority){
  int ret;
  struct sched_param param;
  param.sched_priority = priority;
  ret = sched_setscheduler(getpid(), policy, &param);
  if (ret)
    perror("sched_setscheduler");
  return ret;
}

int main(){
  print_sched();
  printf("sched_setscheduler()->%d\n", set_sched(SCHED_RR, sched_get_priority_max(SCHED_RR)));
  print_sched();
}