.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996

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.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>

.\"            First version written

.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>

.\"            revision

.\"

.TH SCHED_GET_PRIORITY_MAX 2 2017-09-15 "Linux" "Linux Programmer's Manual"

.SH NAME

sched_get_priority_max, sched_get_priority_min  \- get static priority range

.SH SYNOPSIS

.B #include <sched.h>

.PP

.BI "int sched_get_priority_max(int " policy );

.PP

.BI "int sched_get_priority_min(int " policy );

.SH DESCRIPTION

.BR sched_get_priority_max ()

returns the maximum priority value that can be used with the

scheduling algorithm identified by

.IR policy .

.BR sched_get_priority_min ()

returns the minimum priority value that can be used with the

scheduling algorithm identified by

.IR policy .

Supported

.I policy

values are

.BR SCHED_FIFO ,

.BR SCHED_RR ,

.BR SCHED_OTHER ,

.BR SCHED_BATCH ,

.BR SCHED_IDLE ,

and

.BR SCHED_DEADLINE .

Further details about these policies can be found in

.BR sched (7).

.PP

Processes with numerically higher priority values are scheduled before

processes with numerically lower priority values.

Thus, the value

returned by

.BR sched_get_priority_max ()

will be greater than the

value returned by

.BR sched_get_priority_min ().

.PP

Linux allows the static priority range 1 to 99 for the

.B SCHED_FIFO

and

.B SCHED_RR

policies, and the priority 0 for the remaining policies.

Scheduling priority ranges for the various policies

are not alterable.

.PP

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

.BR sched_get_priority_max ()

and

.BR sched_get_priority_min

POSIX.1 requires

.\" POSIX.1-2001, POSIX.1-2008 (XBD 2.8.4)

a spread of at least 32 between the maximum and the minimum values for

.B SCHED_FIFO

and

.BR SCHED_RR .

.PP

POSIX systems on which

.BR sched_get_priority_max ()

and

.BR sched_get_priority_min ()

are available define

.B _POSIX_PRIORITY_SCHEDULING

in

.IR <unistd.h> .

.SH RETURN VALUE

On success,

.BR sched_get_priority_max ()

and

.BR sched_get_priority_min ()

return the maximum/minimum priority value for the named scheduling

policy.

On error, \-1 is returned, and

.I errno

is set appropriately.

.SH ERRORS

.TP

.B EINVAL

The argument

.I policy

does not identify a defined scheduling policy.

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

.SH SEE ALSO

.ad l

.nh

.BR sched_getaffinity (2),

.BR sched_getparam (2),

.BR sched_getscheduler (2),

.BR sched_setaffinity (2),

.BR sched_setparam (2),

.BR sched_setscheduler (2),

.BR sched (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I 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/.