why is thread not running with correct priority in linux

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http://stackoverflow.com – I have following code, which changes priority of current thread. I passed 90 as parameter, yet it looks like thread is running with priority 19. I have: checked that ulimit -r is set to 99 process is running as root How do I know that process is running with priority 19. I executed following command. As you can see pri is 19. Also what is the difference between rtprio and pri? I am using 2.6 kernel from redhat enterprise linux ver 6.3. Since, this is not a real time linux, is this line valid in code if(pthread_setschedparam(pthread_self(), SCHED_RR, &param)) as i am setting scheduler t (HowTos)