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GET_PRIORITY_MAX
!!!GET_PRIORITY_MAX
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO
----
!!NAME


sched_get_priority_max, sched_get_priority_min - get static priority range
!!SYNOPSIS


__#include __


__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'',
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 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
''
!!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 - POSIX.4'' by Bill O.
Gallmeister, O'Reilly
''
IEEE Std 1003.1b-1993'' (POSIX.1b standard)''
ISO/IEC 9945-1:1996''
----

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