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/.


  chrt(1) manpage

Copyright (C) 2004 Robert Love

This is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License.

The GNU General Public License's references to "object code"
and "executables" are to be interpreted as the output of any
document formatting or typesetting system, including
intermediate and printed output.

This manual is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public
License along with this manual; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
USA.

2002-05-11 Robert Love <rmltech9.net>
Initial version