SCHED_GET_PRIORITY_MAX
Section: Linux Programmer's Manual (2)
Updated: 2014-05-12
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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
policy
values are
SCHED_FIFO,
SCHED_RR,
SCHED_OTHER,
SCHED_BATCH,
SCHED_IDLE,
and
SCHED_DEADLINE.
Further details about these policies can be found in
sched(7).
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 range 1 to 99 for the
SCHED_FIFO
and
SCHED_RR
policies, and the priority 0 for the remaining policies.
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.1-2001 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>.
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, and
errno
is set appropriately.
ERRORS
- EINVAL
-
The argument
policy
does not identify a defined scheduling policy.
CONFORMING TO
POSIX.1-2001.
SEE ALSO
sched_getaffinity(2),
sched_getparam(2),
sched_getscheduler(2),
sched_setaffinity(2),
sched_setparam(2),
sched_setscheduler(2),
sched(7)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- SEE ALSO
-
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Time: 02:54:47 GMT, September 18, 2014