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chrt

CHRT(1) 							   User Commands							   CHRT(1)

NAME

       chrt - manipulate the real-time attributes of a process

SYNOPSIS

       chrt [options] priority command [argument...]
       chrt [options] -p [priority] pid

DESCRIPTION

       chrt sets or retrieves the real-time scheduling attributes of an existing pid, or runs command with the given attributes.

POLICIES

       -o, --other
	      Set scheduling policy to SCHED_OTHER.  This is the default Linux scheduling policy.

       -f, --fifo
	      Set scheduling policy to SCHED_FIFO.

       -r, --rr
	      Set scheduling policy to SCHED_RR.  When no policy is defined, the SCHED_RR is used as the default.

       -b, --batch
	      Set scheduling policy to SCHED_BATCH (Linux-specific, supported since 2.6.16).  The priority argument has to be set to zero.

       -i, --idle
	      Set scheduling policy to SCHED_IDLE (Linux-specific, supported since 2.6.23).  The priority argument has to be set to zero.

       -d, --deadline
	      Set  scheduling  policy to SCHED_DEADLINE (Linux-specific, supported since 3.14).  The priority argument has to be set to zero.  See
	      also --sched-runtime, --sched-deadline and --sched-period.  The relation between the options required by the kernel  is  runtime	<=
	      deadline	<= period.  chrt copies period to deadline if --sched-deadline is not specified and deadline to runtime if --sched-runtime
	      is not specified.  It means that at least --sched-period has to be specified.  See sched(7) for more details.

SCHEDULING OPTIONS

       -T, --sched-runtime nanoseconds
	      Specifies runtime parameter for SCHED_DEADLINE policy (Linux-specific).

       -P, --sched-period nanoseconds
	      Specifies period parameter for SCHED_DEADLINE policy (Linux-specific).

       -D, --sched-deadline nanoseconds
	      Specifies deadline parameter for SCHED_DEADLINE policy (Linux-specific).

       -R, --reset-on-fork
	      Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR scheduling policy (Linux-specific, supported since 2.6.31).

OPTIONS

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

       -m, --max
	      Show minimum and maximum valid priorities, then exit.

       -p, --pid
	      Operate on an existing PID and do not launch a new task.

       -v, --verbose
	      Show status information.

       -V, --version
	      Display version information and exit.

       -h, --help
	      Display help text and exit.

USAGE

       The default behavior is to run a new command:
	      chrt priority command [arguments]

       You can also retrieve the real-time attributes of an existing task:
	      chrt -p pid

       Or set them:
	      chrt -r -p priority 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.

SEE ALSO

       nice(1), renice(1), taskset(1), sched(7)

       See sched_setscheduler(2) for a description of the Linux scheduling scheme.

AUTHORS

       Robert Love <rml@tech9.net>
       Karel Zak <kzak@redhat.com>

AVAILABILITY

       The chrt command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux							   January 2016 							   CHRT(1)