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 algo-
       rithm identified 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_pri-
       ority_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_prior-
       ity_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_priority_min  are available define _POSIX_PRIOR-
       ITY_SCHEDULING in <unistd.h>.

RETURN VALUE
       On success,  sched_get_priority_max  and  sched_get_prior-
       ity_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_set-
       param(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                          1