NAME

       sched_get_priority_max, sched_get_priority_min  - get static priority range

LIBRARY

       Standard C library (libc, -lc)

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 returned  by  sched_get_priority_max()
       will be greater than the value returned 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 priority range and map it to the interval given
       by  sched_get_priority_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_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 to indicate the error.

ERRORS

       EINVAL The argument policy does not identify a defined scheduling policy.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001.

SEE ALSO

       sched_getaffinity(2), sched_getparam(2), sched_getscheduler(2), sched_setaffinity(2),
       sched_setparam(2), sched_setscheduler(2), sched(7)