sched_getscheduler(3)sched_getscheduler(3)NAMEsched_getscheduler - Returns the scheduling policy of a process
(P1003.1b)
SYNOPSIS
#include <sched.h>
int sched_getscheduler ( pid_t pid);
LIBRARY
Realtime Library (librt.so, librt.a)
PARAMETERS
Specifies the ID of the process for which the scheduling policy is to
be obtained. If pid is zero, the scheduling policy of the calling
process is obtained.
DESCRIPTION
The sched_getscheduler function returns the current scheduling policy
of a process. The values that can be returned are defined in the header
file <sched.h>.
The sched_setscheduler function changes the scheduling policy and pri‐
ority of a process. Changing the scheduling policy and priority ensures
that an application can determine more effectively when a process will
run.
The realtime scheduling policies are as follows: Specifies the first-
in, first-out (FIFO) scheduling policy Specifies the round-robin (RR)
scheduling policy Specifies the standard timesharing scheduling policy
The SCHED_FIFO and SCHED_RR scheduling policies are fixed-priority
scheduling policies. You can specify a priority for your process and
the scheduler will not adjust it. Setting priorities in conjunction
with a SCHED_FIFO scheduling policy allows a critical process to run as
soon as it is ready, for as long as it needs to run, because the
process will preempt other lower-priority processes.
The round-robin scheduling policy is similar to first in-first out, but
also imposes a quantum on execution time. Use the sched_rr_get_interval
function to determine the current quantum for process execution under
the SCHED_RR scheduling policy.
The scheduler adjusts process priorities running under the timesharing
scheduling policy.
No special privileges are needed to use the sched_getscheduler func‐
tion.
RETURN VALUES
On a successful call to sched_getscheduler, the scheduling policy of
the process is returned. If there is an error, -1 is returned and errno
is set to indicate the error.
ERRORS
The sched_getscheduler function fails under the following condition: No
process can be found corresponding to that specified by pid.
SEE ALSO
Functions: getpid(2), sched_getparam(3), sched_setparam(3),
sched_setscheduler(3)
Guide to Realtime Programming
sched_getscheduler(3)