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CHRT(1) User Commands CHRT(1)

NAME

chrt - manipulate the real-time attributes of a process

SYNOPSIS

chrt [optionsprio command [arg]...
chrt [options] -p [priopid

DESCRIPTION

chrt 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.

The SCHED_RESET_ON_FORK flag for policies SCHED_RR and SCHED_FIFO is supported since Linux 2.6.31.

OPTIONS

Set or retrieve the scheduling attributes of all the tasks (threads) for a given PID.
Set scheduling policy to SCHED_BATCH (Linux specific).
Set scheduling policy to SCHED_FIFO.
Set scheduling policy to SCHED_IDLE (Linux specific).
Show minimum and maximum valid priorities, then exit.
Set policy scheduling policy to SCHED_OTHER.
Operate on an existing PID and do not launch a new task.
Set scheduling policy to SCHED_RR. When policy is not defined the SCHED_RR is used as default.
Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR scheduling policy (Linux specific).
Show status information.
Display usage information and exit.
Display version information and exit.

USAGE

chrt prio command [arguments]
chrt -p pid
chrt -r -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.

Linux default scheduling policy is SCHED_OTHER.

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

June 2010 util-linux