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 identi-
     fied by policy.  Supported  policy  values  are  SCHED_FIFO,
     SCHED_RR, and SCHED_OTHER.

     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.
     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.1b requires a spread of at least 32 between  the  max-
     imum 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, errno is set appropriately.

ERRORS

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

CONFORMING TO

     POSIX.1b (formerly POSIX.4)

SEE ALSO

     sched_setscheduler(2),                sched_getscheduler(2),
     sched_setparam(2), sched_getparam(2).

     sched_setscheduler(2)  has  a  description  of   the   Linux
     scheduling scheme.

     Programming for the real world -  by  Bill  O.  Gallmeister,
     O'Reilly & Associates, Inc., ISBN 1-56592-074-0
     IEEE Std 1003.1b-1993 (POSIX.1b standard)
     ISO/IEC 9945-1:1996