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 <unistd.h>.
