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.
POLICIES
-o, --other
-f, --fifo
-r, --rr
-b, --batch
-i, --idle
-d, --deadline
SCHEDULING OPTIONS
-T, --sched-runtimenanoseconds
-P, --sched-periodnanoseconds
-D, --sched-deadlinenanoseconds
-R, --reset-on-fork
Each thread has a reset-on-fork scheduling flag. When this flag is set, children created by fork(2) do not inherit privileged scheduling policies. After the reset-on-fork flag has been enabled, it can be reset only if the thread has the CAP_SYS_NICE capability. This flag is disabled in child processes created by fork(2).
More precisely, if the reset-on-fork flag is set, the following rules apply for subsequently created children:
OPTIONS
-a, --all-tasks
-m, --max
-p, --pid
-v, --verbose
-h, --help
-V, --version
EXAMPLES
The default behavior is to run a new command:
chrtprioritycommand [arguments]
You can also retrieve the real-time attributes of an existing task:
chrt -pPID
Or set them:
chrt -r -ppriority PID
This, for example, sets real-time scheduling to priority 30 for the process PID with the SCHED_RR (round-robin) class:
chrt -r -p 30PID
Reset priorities to default for a process:
chrt -o -p 0PID
See sched(7) for a detailed discussion of the different scheduler classes and how they interact.
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.
AUTHORS
Robert Love <[email protected]>, Karel Zak <[email protected]>
SEE ALSO
nice(1), renice(1), taskset(1), sched(7)
See sched_setscheduler(2) for a description of the Linux scheduling scheme.
REPORTING BUGS
For bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>.
AVAILABILITY
The chrt command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.