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, and
SCHED_BATCH. Further details about these policies can be found in
sched_setscheduler(2).
Processes with numerically higher priority values are scheduled before processes with numerically lower priority values. Thus, the value returned by
sched_get_priority_max() will be greater than the value returned by
sched_get_priority_min().
Linux allows the static priority value range 1 to 99 for
SCHED_FIFO and
SCHED_RR and the priority 0 for
SCHED_OTHER and
SCHED_BATCH. 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 priority range and map it to the interval given by
sched_get_priority_max() and
sched_get_priority_min(). POSIX.1-2001 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_priority_min() are available define
_POSIX_PRIORITY_SCHEDULING in
<unistd.h>.
RETURN VALUE
On success,
sched_get_priority_max() and
sched_get_priority_min() return the maximum/minimum priority value for the named scheduling policy. On error, -1 is returned, and
errno is set appropriately.
ERRORS
-
EINVAL
-
The argument
policy does not identify a defined scheduling policy.
CONFORMING TO
POSIX.1-2001.
SEE ALSO
sched_getaffinity(2),
sched_getparam(2),
sched_getscheduler(2),
sched_setaffinity(2),
sched_setparam(2),
sched_setscheduler(2)
Programming for the real world - POSIX.4 by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0.
COLOPHON
This page is part of release 3.53 of the Linux
man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.