NAME¶

chrt - manipulate real-time attributes of a process

SYNOPSIS¶

chrt [options] prio command [arg]...
chrt [options] -p [prio] pid

DESCRIPTION¶

chrt(1) 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.

OPTIONS¶

-p, --pid

operate on an existing PID and do not launch a new task

-b, --batch

set scheduling policy to SCHED_BATCH (Linux specific)

-f, --fifo

set scheduling policy to SCHED_FIFO

-i, --idle

set schedulng 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

-r, --rr

set scheduling policy to SCHED_RR (the default)

-h, --help

display usage information and exit

-v, --version

output 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-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.