SCHED_GET_PRIORITY_MAX(2) Linux Programmer's Manual SCHED_GET_PRIORITY_MAX(2)
NAME
sched_get_priority_max, sched_get_priority_min - get static priority
range
SYNOPSIS
#include <sched.h>
int sched_get_priority_max(int policy);
int sched_get_priority_min(int policy);
DESCRIPTION
sched_get_priority_max() returns the maximum priority value that can be
used with the scheduling algorithm identified by policy.
sched_get_priority_min() returns the minimum priority value that can be
used with the scheduling algorithm identified by policy. Supported
policy values are SCHED_FIFO, SCHED_RR, SCHED_OTHER, SCHED_BATCH,
SCHED_IDLE, and SCHED_DEADLINE. Further details about these policies
can be found in sched(7).
Processes with numerically higher priority values are scheduled before
processes with numerically lower priority values. Thus, the value re-
turned by sched_get_priority_max() will be greater than the value re-
turned by sched_get_priority_min().
Linux allows the static priority range 1 to 99 for the SCHED_FIFO and
SCHED_RR policies, and the priority 0 for the remaining policies.
Scheduling priority ranges for the various policies are not alterable.
The range of scheduling priorities may vary on other POSIX systems,
thus it is a good idea for portable applications to use a virtual pri-
ority range and map it to the interval given by sched_get_prior-
ity_max() and sched_get_priority_min POSIX.1 requires a spread of at
least 32 between the maximum and the minimum values for SCHED_FIFO and
SCHED_RR.
POSIX systems on which sched_get_priority_max() and sched_get_prior-
ity_min() are available define _POSIX_PRIORITY_SCHEDULING in
<unistd.h>.
RETURN VALUE
On success, sched_get_priority_max() and sched_get_priority_min() re-
turn the maximum/minimum priority value for the named scheduling pol-
icy. On error, -1 is returned, and errno is set appropriately.
ERRORS
EINVAL The argument policy does not identify a defined scheduling pol-
icy.
CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
SEE ALSO
sched_getaffinity(2), sched_getparam(2), sched_getscheduler(2),
sched_setaffinity(2), sched_setparam(2), sched_setscheduler(2),
sched(7)
COLOPHON
This page is part of release 5.07 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2017-09-15 SCHED_GET_PRIORITY_MAX(2)