Dr Andrew Scott
G7VAV
Senior Lecturer
School of Computing
and Communications
D35 InfoLab21
Lancaster University
Lancaster, LA1 4WA
United Kingdom
School of Computing
and Communications
D35 InfoLab21
Lancaster University
Lancaster, LA1 4WA
United Kingdom
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CHRT
Section: User Commands (1)Updated: June 2010
Index Return to Main Contents
NAME
chrt - manipulate the real-time attributes of a processSYNOPSIS
chrt [options] prio command [arg]...chrt [options] -p [prio] pid
DESCRIPTION
chrt sets or retrieves the real-time scheduling attributes of an existing pid, or runs command with the given attributes. Both policy (one of SCHED_OTHER, SCHED_FIFO, SCHED_RR, SCHED_BATCH, or SCHED_IDLE) and 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).
- -f, --fifo
- Set scheduling policy to SCHED_FIFO.
- -i, --idle
- Set scheduling policy to SCHED_IDLE (Linux specific).
- -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, --rr
- Set scheduling policy to SCHED_RR (the default).
- -R, --reset-on-fork
- Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR scheduling policy (Linux specific).
- -v, --verbose
- Show status information.
- -h, --help
- Display usage information and exit.
- -V, --version
- Display version information and exit.
USAGE
- The default behavior is to run a new command:
- chrt prio command [arguments]
- You can also retrieve the real-time attributes of an existing task:
- chrt -p pid
- Or set them:
- chrt -p prio 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.AUTHOR
Written by Robert M. Love.COPYRIGHT
Copyright © 2004 Robert M. LoveThis is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
taskset(1), nice(1), renice(1)See sched_setscheduler(2) for a description of the Linux scheduling scheme.
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
for client
(none)
© Andrew Scott 2006 -
2025,
All Rights Reserved
All Rights Reserved
Andrew Scott