sched_getscheduler - Returns the scheduling policy of a
int sched_getscheduler ( pid_t pid);
Realtime Library (librt.so, librt.a)
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.
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 priority 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 fixedpriority
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 infirst
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
The scheduler adjusts process priorities running under the
timesharing scheduling policy.
No special privileges are needed to use the
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.
The sched_getscheduler function fails under the following
condition: No process can be found corresponding to that
specified by pid.
Functions: getpid(2), sched_getparam(3), sched_setparam(3), sched_setscheduler(3)
Guide to Realtime Programming
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