CHRT
Section: User Commands (1)
Updated: August 2014
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NAME
chrt - manipulate the real-time attributes of a process
SYNOPSIS
chrt
[options]
priority command [argument...]
chrt
[options]
-p
[priority] pid
DESCRIPTION
chrt
sets or retrieves the real-time scheduling attributes of an existing pid,
or runs command with the given attributes. Both the policy (one of
SCHED_OTHER,
SCHED_FIFO,
SCHED_RR,
SCHED_BATCH,
or
SCHED_IDLE)
and the priority can be set and retrieved.
The
SCHED_BATCH
policy is supported since Linux 2.6.16. The
SCHED_IDLE
policy is supported since Linux 2.6.23.
The
SCHED_RESET_ON_FORK
flag for policies SCHED_RR and SCHED_FIFO is supported
since Linux 2.6.31.
OPTIONS
- -a, --all-tasks
-
Set or retrieve the scheduling attributes of all the tasks (threads) for a
given PID.
- -b, --batch
-
Set scheduling policy to
SCHED_BATCH
(Linux-specific). The priority argument has to be set to zero.
- -f, --fifo
-
Set scheduling policy to
SCHED_FIFO.
- -i, --idle
-
Set scheduling policy to
SCHED_IDLE
(Linux-specific). The priority argument has to be set to zero.
- -m, --max
-
Show minimum and maximum valid priorities, then exit.
- -o, --other
-
Set policy scheduling policy to
SCHED_OTHER.
- -p, --pid
-
Operate on an existing PID and do not launch a new task.
- -R, --reset-on-fork
-
Add
SCHED_RESET_ON_FORK
flag to the
SCHED_FIFO
or
SCHED_RR
scheduling policy (Linux-specific).
- -r, --rr
-
Set scheduling policy to
SCHED_RR.
When policy is not defined the
SCHED_RR
is used as default.
- -v, --verbose
-
Show status information.
- -V, --version
-
Display version information and exit.
- -h, --help
-
Display help text and exit.
USAGE
- The default behavior is to run a new command:
-
chrt
priority
command [arguments]
- You can also retrieve the real-time attributes of an existing task:
-
chrt -p
pid
- Or set them:
-
chrt -r -p
priority pid
PERMISSIONS
A user must possess
CAP_SYS_NICE
to change the scheduling attributes of a process. Any user can retrieve the
scheduling information.
NOTES
Only
SCHED_FIFO,
SCHED_OTHER
and
SCHED_RR
are part of POSIX 1003.1b Process Scheduling. The other scheduling attributes
may be ignored on some systems.
Linux default scheduling policy is
SCHED_OTHER.
SEE ALSO
taskset(1),
nice(1),
renice(1)
See
sched_setscheduler(2)
for a description of the Linux scheduling scheme.
AUTHOR
Written by Robert M. Love.
COPYRIGHT
Copyright © 2004 Robert M. Love.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
AVAILABILITY
The chrt command is part of the util-linux package and is available from
ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- USAGE
-
- PERMISSIONS
-
- NOTES
-
- SEE ALSO
-
- AUTHOR
-
- COPYRIGHT
-
- AVAILABILITY
-