Programming Interfaces Guide

Interactions With Other Interfaces

Altering the priority of a process in the TS class can affect the behavior of other processes in the TS class. This section identifies ways in which a scheduling change can affect other processes.

Kernel Processes

The kernel's daemon and housekeeping processes are members of the system scheduler class. Users can neither add processes to nor remove processes from this class, nor can users change the priorities of these processes. The command ps -cel lists the scheduler class of all processes. A SYS entry in the CLS column identifies processes in the system class when you run ps(1) with the -f option.

Using fork and exec

Scheduler class, priority, and other scheduler parameters are inherited across the fork(2) and exec(2) interfaces.

Using nice

The nice(1) command and the nice(2) interface work as in previous versions of the UNIX system. These commands enable you to change the priority of a time-sharing process. Use lower numeric values to assign higher time-sharing priorities with these interfaces.

To change the scheduler class of a process or to specify a real-time priority, use priocntl(2). Use higher numeric values to assign higher priorities.


Theinit(1M) process is a special case to the scheduler. To change the scheduling properties of init(1M), init must be the only process specified by idtype and id or by the procset structure.