change realtime priority of a linux process

Get the sample program from here

[root@localhost ~]# uname -a
Linux ... 2.6.21-1.3194.fc7 #1 SMP ... GNU/Linux

# gcc -o realtime linux_realtime.c
# ./realtime
Round-robin quantum is 0 seconds, 99984800 nanoseconds
Sched getparam: current policy 0
Sched getparam: current priority 0
RR min prio: 1
RR max prio: 99
Completed test 0
Completed test 1
Completed test 2
Completed test 3
Completed test 4
Completed test 5
Completed test 6
Completed test 7
Completed test 8
Completed test 9

Reference:
http://www.helsinki.fi/atk/unix/dec_manuals/DOC_40D/APS33DTE/DOCU_003.HTM