GETPRIORITY(2) | System Calls Manual | GETPRIORITY(2) |
getpriority
, setpriority
—
#include <sys/resource.h>
int
getpriority
(int
which, id_t
who);
int
setpriority
(int
which, id_t who,
int prio);
getpriority
() call and set with the
setpriority
() call.
The priority is maintained in a per-process basis and affects
scheduling of LWPs which belong to the process and use the
SCHED_OTHER
scheduling class.
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; numerically lower priority values 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 priority values.
getpriority
() can legitimately return the value
-1, it is necessary to clear the external variable errno
prior to the call, then check it afterward to determine if a -1 is an error or
a legitimate value. The setpriority
() call returns 0
if there is no error, or -1 if there is.
getpriority
() and setpriority
()
will fail if:
EINVAL
]PRIO_PROCESS
, PRIO_PGRP
,
or PRIO_USER
.ESRCH
]In addition to the errors indicated above,
setpriority
() will fail if:
getpriority
() function call appeared in
4.2BSD.
April 13, 2012 | NetBSD 9.0 |