RT_PREEMPT - Scheduler priority

[Below are comments reported by Brad during his RT_PREEMPT testings]

If you don't use sudo to run ./ex04_display_basic_info, the call to sched_setschedler will fail with a permission problem, but the program will continue to run. This will allow you to run the program without making use of RT_PREEMPT and a high priority thread. If you do run the program without using sudo you should see the message in the shell: Yikes, the call to sched_setscheduler failed

This is okay; it just means your thread is running at standard priority.