redhat man page for sched_get_priority_max

GET_PRIORITY_MAX(2)					     Linux Programmer's Manual					       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, 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 pri-
       ority 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_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

Linux 1.3.81							    1996-04-10						       GET_PRIORITY_MAX(2)