− get the SCHED_RR interval for the named process
sched_rr_get_interval(pid_t pid, struct
timespec * tp);
writes into the timespec structure pointed to by
tp the round-robin time quantum for the process
identified by pid. The specified process should be
running under the SCHED_RR scheduling policy.
timespec structure has the following form:
time_t tv_sec; /* seconds */
long tv_nsec; /* nanoseconds */
is zero, the time quantum for the calling process is written
sched_rr_get_interval() returns 0. On error, −1
is returned, and errno is set appropriately.
Problem with copying information
to user space.
The system call is not yet implemented (only on rather
Could not find a process with the ID pid.
on which sched_rr_get_interval() is available define
POSIX does not specify any mechanism for controlling the
size of the round-robin time quantum. Older Linux kernels
provide a (nonportable) method of doing this. The quantum
can be controlled by adjusting the process’s nice
value (see setpriority(2)). Assigning a negative
(i.e., high) nice value results in a longer quantum;
assigning a positive (i.e., low) nice value results in a
shorter quantum. The default quantum is 0.1 seconds; the
degree to which changing the nice value affects the quantum
has varied somewhat across kernel versions. This method of
adjusting the quantum was removed starting with Linux
Linux 3.9 added
a new mechanism for adjusting (and viewing) the
SCHED_RR quantum: the
/proc/sys/kernel/sched_rr_timeslice_ms file exposes
the quantum as a millisecond value, whose default is 100.
Writing 0 to this file resets the quantum to the default
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