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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, and
       SCHED_BATCH.  Further details about these policies can be found in sched_setscheduler(2).

       Processes with numerically higher priority values are scheduled before processes with numerically lower  prior-
       ity  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 and SCHED_BATCH.  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 appli-
       cations to use a virtual priority range and map it  to  the  interval  given  by  sched_get_priority_max()  and
       sched_get_priority_min().   POSIX.1-2001  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_PRIOR-
       ITY_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 appropriately.

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

CONFORMING TO
       POSIX.1-2001.

SEE ALSO
       sched_getaffinity(2),  sched_getparam(2),   sched_getscheduler(2),   sched_setaffinity(2),   sched_setparam(2),
       sched_setscheduler(2)

       Programming  for  the  real  world  -  POSIX.4  by  Bill  O.  Gallmeister,  O'Reilly  &  Associates, Inc., ISBN
       1-56592-074-0

COLOPHON
       This page is part of release 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2006-03-23         SCHED_GET_PRIORITY_MAX(2)