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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,  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 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()
     return 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 4.16 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)