Linux Commands Examples

A great documentation place for Linux commands


manipulate the real-time attributes of a process

see also : taskset - nice - renice


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

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echo $PIDs
for i in $PIDs
echo "Changing pid $i"
ret=$(chrt -f -p 99 $i)
PIDs=$(ps -eLo pid,cls,rtprio,pri,nice,cmd | grep -i "cpuset" | awk '{ print $1; }' | xargs echo)
for i in $PIDs
echo "Changing pid $i"
ret=$(chrt -f -p 99 $i)
PROCESS_NAMES="srcds_linux srcds_i686 srcds_i486 srcds_amd hlds_i686 hlds_i486 hlds_amd"
for name in $PROCESS_NAMES; do
PIDS=`pidof $name`
for p in $PIDS; do
chrt -f -p 98 $p
PIDS=`ps ax | grep sirq-hrtimer | grep -v grep | sed -e "s/^ *//" -e "s/ .*$//"`
for p in $PIDS; do
chrt -f -p 99 $p


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.


-a, --all-tasks

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

-b, --batch

Set scheduling policy to SCHED_BATCH (Linux specific).

-f, --fifo

Set scheduling policy to SCHED_FIFO.

-i, --idle

Set scheduling 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.

-p, --pid

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

-r, --rr

Set scheduling policy to SCHED_RR (the default).

-R, --reset-on-fork

Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR scheduling policy (Linux specific).

-v, --verbose

Show status information.

-h, --help

Display usage information and exit.

-V, --version

Display version information and exit.


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


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.


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.


A user must possess CAP_SYS_NICE to change the scheduling attributes of a process. Any user can retrieve the scheduling information.


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

see also

taskset , nice , renice

See sched_setscheduler for a description of the Linux scheduling scheme.


Written by Robert M. Love.

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