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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
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SCHED_RR_GET_INTERVAL(2)Linux Programmer's ManualCHED_RR_GET_INTERVAL(2)
sched_rr_get_interval - get the SCHED_RR interval for the named
process
#include <sched.h>
int sched_rr_get_interval(pid_t pid, struct timespec *tp);
sched_rr_get_interval() 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.
The timespec structure has the following form:
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* nanoseconds */
};
If pid is zero, the time quantum for the calling process is
written into *tp.
On success, sched_rr_get_interval() returns 0. On error, -1 is
returned, and errno is set to indicate the error.
EFAULT Problem with copying information to user space.
EINVAL Invalid pid.
ENOSYS The system call is not yet implemented (only on rather old
kernels).
ESRCH Could not find a process with the ID pid.
POSIX.1-2001, POSIX.1-2008.
POSIX systems on which sched_rr_get_interval() is available
define _POSIX_PRIORITY_SCHEDULING in <unistd.h>.
Linux notes
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
2.6.24.
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 value.
sched(7)
This page is part of release 5.13 of the Linux man-pages project.
A description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2021-03-22 SCHED_RR_GET_INTERVAL(2)
Pages that refer to this page: sched_setattr(2), sched_setscheduler(2), syscalls(2), proc(5), sched(7)
Copyright and license for this manual page
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