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 (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. 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/.
