sched_get_priority_min(2) -- Linux man page
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,
and
SCHED_OTHER.
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. 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.1b 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,
errno
is set appropriately.
ERRORS
- EINVAL
-
The parameter policy does not identify a defined scheduling policy.
CONFORMING TO
POSIX.1b (formerly POSIX.4)
SEE ALSO
sched_setaffinity(2),
sched_getaffinity(2),
sched_setscheduler(2),
sched_getscheduler(2),
sched_setparam(2),
sched_getparam(2)
sched_setscheduler(2)
has a description of the Linux scheduling scheme.
Programming for the real world - POSIX.4
by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0
IEEE Std 1003.1b-1993
(POSIX.1b standard)
ISO/IEC 9945-1:1996
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