sched_get_priority_max

GET_PRIORITY_MAX(2)        Linux Programmer's Manual       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 pol-
       icy 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  pri-
       ority  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 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 policy.  On
       error, -1 is returned, errno is set appropriately.

ERRORS
       EINVAL The parameter policy does not identify a defined scheduling pol-
              icy.

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  -  POSIX.4  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



Linux 1.3.81                      1996-04-10               GET_PRIORITY_MAX(2)