sched_get_priority_max

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 5.05 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)