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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  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   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 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.1-2001
       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_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 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

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