CHRT(1) User Commands CHRT(1)
chrt - manipulate the real-time attributes of a process
chrt [options] priority command argument ... chrt [options] -p [priority] PID
chrt sets or retrieves the real-time scheduling attributes of an existing PID, or runs command with the given attributes.
-o, --other Set scheduling policy to SCHED_OTHER (time-sharing scheduling). This is the default Linux scheduling policy. -f, --fifo Set scheduling policy to SCHED_FIFO (first in-first out). -r, --rr Set scheduling policy to SCHED_RR (round-robin scheduling). When no policy is defined, the SCHED_RR is used as the default. -b, --batch Set scheduling policy to SCHED_BATCH (scheduling batch processes). Linux-specific, supported since 2.6.16. The priority argument has to be set to zero. -i, --idle Set scheduling policy to SCHED_IDLE (scheduling very low priority jobs). Linux-specific, supported since 2.6.23. The priority argument has to be set to zero. -d, --deadline Set scheduling policy to SCHED_DEADLINE (sporadic task model deadline scheduling). Linux-specific, supported since 3.14. The priority argument has to be set to zero. See also --sched-runtime, --sched-deadline and --sched-period. The relation between the options required by the kernel is runtime ⇐ deadline ⇐ period. chrt copies period to deadline if --sched-deadline is not specified and deadline to runtime if --sched-runtime is not specified. It means that at least --sched-period has to be specified. See sched(7) for more details.
-T, --sched-runtime nanoseconds Specifies runtime parameter for SCHED_DEADLINE policy (Linux-specific). -P, --sched-period nanoseconds Specifies period parameter for SCHED_DEADLINE policy (Linux-specific). -D, --sched-deadline nanoseconds Specifies deadline parameter for SCHED_DEADLINE policy (Linux-specific). -R, --reset-on-fork Use SCHED_RESET_ON_FORK or SCHED_FLAG_RESET_ON_FORK flag. Linux-specific, supported since 2.6.31. 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: • If the calling thread has a scheduling policy of SCHED_FIFO or SCHED_RR, the policy is reset to SCHED_OTHER in child processes. • If the calling process has a negative nice value, the nice value is reset to zero in child processes.
-a, --all-tasks Set or retrieve the scheduling attributes of all the tasks (threads) for a given PID. -m, --max Show minimum and maximum valid priorities, then exit. -p, --pid Operate on an existing PID and do not launch a new task. -v, --verbose Show status information. -V, --version Display version information and exit. -h, --help Display help text and exit.
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
A user must possess CAP_SYS_NICE to change the scheduling attributes of a process. Any user can retrieve the scheduling information.
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.
Robert Love <email@example.com>, Karel Zak <firstname.lastname@example.org>
nice(1), renice(1), taskset(1), sched(7) See sched_setscheduler(2) for a description of the Linux scheduling scheme.
For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.
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/>. This page is part of the util-linux (a random collection of Linux utilities) project. Information about the project can be found at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a bug report for this manual page, send it to email@example.com. This page was obtained from the project's upstream Git repository ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on 2021-08-27. (At that time, the date of the most recent commit that was found in the repository was 2021-08-24.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to firstname.lastname@example.org util-linux 2.37.85-637cc 2021-04-02 CHRT(1)
Pages that refer to this page: renice(1), taskset(1), sched_setattr(2), sched_setscheduler(2), sched(7)