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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 exist‐
       ing 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,  sup‐
	      ported  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-spe‐
	      cific).

       -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)

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