chrt

Manipulate real-time scheduling attributes of processes

TLDR

Display scheduling attributes of a process

$ chrt -p PID

Display attributes of all threads of a process

$ chrt -a -p PID

Show min/max priority values

$ chrt -m

Set scheduling priority of a process

$ chrt -p priority PID

Set FIFO scheduling policy

$ chrt --fifo -p priority PID

Set round-robin scheduling policy

$ chrt --rr -p priority PID

Run command with idle scheduling

$ chrt --idle 0 command

SYNOPSIS

chrt [options] priority command [argument...]chrt [options] -p [priority] PID

chrt sets or retrieves the real-time scheduling attributes of an existing process, or runs a command with specified scheduling attributes. It supports various Linux scheduling policies including FIFO, round-robin, batch, idle, and deadline.Real-time scheduling policies (SCHEDFIFO, SCHEDRR) give processes priority over normal tasks, which is critical for time-sensitive applications like audio processing, industrial control, and high-frequency trading. Non-real-time policies (SCHEDBATCH, SCHEDIDLE) are useful for background workloads that should yield to interactive processes.The tool is part of the util-linux package and operates via the sched_setscheduler(2) and sched_setattr(2) system calls.

PARAMETERS

-p, --pid

Operate on an existing PID without launching a new task

-a, --all-tasks

Set or retrieve scheduling attributes for all threads of a PID

-m, --max

Show minimum and maximum valid priorities for each policy

-v, --verbose

Show status information

-R, --reset-on-fork

Children do not inherit privileged scheduling policies

-o, --other

Set SCHED_OTHER policy (default Linux time-sharing)

-f, --fifo

Set SCHED_FIFO policy (first in-first out)

-r, --rr

Set SCHED_RR policy (round-robin, default when no policy given)

-b, --batch

Set SCHED_BATCH policy for batch processing (priority must be 0)

-i, --idle

Set SCHED_IDLE policy for very low priority tasks (priority must be 0)

-d, --deadline

Set SCHED_DEADLINE policy for sporadic deadline scheduling (priority must be 0)

INSTALL

sudo apt install util-linux

sudo dnf install util-linux

sudo pacman -S util-linux

sudo apk add util-linux-misc

sudo zypper install util-linux

brew install util-linux

nix profile install nixpkgs#util-linux

CAVEATS

Users require CAPSYSNICE capability to modify scheduling attributes. SCHEDBATCH, SCHEDIDLE, and SCHEDDEADLINE policies require priority 0. Only SCHEDFIFO, SCHEDOTHER, and SCHEDRR are part of POSIX 1003.1b.

HISTORY

chrt is part of the util-linux package, providing real-time process scheduling control since Linux 2.6.