CHRT(1) 							   User Commands							   CHRT(1)

NAME

       chrt - manipulate the real-time attributes of a process

SYNOPSIS

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

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

       -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.

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 (C) 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 PARTICU-
       LAR 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/.

util-linux							     June 2010								   CHRT(1)