chrt — manipulate the real-time attributes of a process


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


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. This is the default Linux scheduling policy.

-f, --fifo

Set scheduling policy to SCHED_FIFO.

-r, --rr

Set scheduling policy to SCHED_RR. When no policy is defined, the SCHED_RR is used as the default.

-b, --batch

Set scheduling policy to SCHED_BATCH (Linux-specific, supported since 2.6.16).  The priority argument has to be set to zero.

-i, --idle

Set scheduling policy to SCHED_IDLE (Linux-specific, supported since 2.6.23).  The priority argument has to be set to zero.


Set scheduling policy to SCHED_DEADLINE (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.

Scheduling Options

-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

Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR scheduling policy (Linux-specific, supported since 2.6.31).



Set or retrieve the scheduling attributes of all the tasks (threads) for a given PID.


Show minimum and maximum valid priorities, then exit.


Operate on an existing PID and do not launch a new task.


Show status information.


Display version information and exit.


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.

See Also

nice(1), renice(1), taskset(1), sched(7)

See sched_setscheduler(2) for a description of the Linux scheduling scheme.


Robert Love
Karel Zak


The chrt command is part of the util-linux package and is available from

Referenced By

pchrt(1), sched(7), sched_setattr(2), sched_setscheduler(2), spausedd(8), taskset(1).

January 2016 util-linux