You can configure the process scheduling classes on your system and the user priority range for the timesharing class.
The possible process scheduling classes are as follows:
Fair share (FSS)
Fixed (FX)
System (SYS)
Interactive (IA)
Real-time (RT)
The priority of a process is inherited from the parent process. This priority is referred to as the user-mode priority.
The system looks up the user-mode priority in the timesharing dispatch parameter table. Then, the system adds in any nice or priocntl (user-supplied) priority and ensures a 0–59 range to create a global priority.