table of contents
CHRT(1) | User Commands | CHRT(1) |
NAME¶
chrt - manipulate the real-time attributes of a process
SYNOPSIS¶
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. When policy is not defined the SCHED_RR is used as 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 -r -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.
Linux default scheduling policy is SCHED_OTHER.
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.
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/.
June 2010 | util-linux |