The scheduling priority of the process, process group, or user, as indicated by
which and
who is obtained with the
getpriority() call and set with the
setpriority() call.
which is one of
PRIO_PROCESS,
PRIO_PGRP, or
PRIO_USER, and
who is interpreted relative to
which (a process identifier for
PRIO_PROCESS, process group identifier for
PRIO_PGRP, and a user ID for
PRIO_USER). A zero value of
who denotes the current process, process group, or user.
prio is a value in the range -20 to 20. The default priority is 0; lower priorities cause more favorable scheduling. A value of 19 or 20 will schedule a process only when nothing at priority ≤ 0 is runnable.
The
getpriority() call returns the highest priority (lowest numerical value) enjoyed by any of the specified processes. The
setpriority() call sets the priorities of all of the specified processes to the specified value. Only the super-user may lower priorities.