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.

AUTHORS
       Robert Love ⟨rml@tech9.net⟩
       Karel Zak ⟨kzak@redhat.com⟩

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

       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 https://www.kernel.org/pub/linux/utils/util-linux/.



util-linux                       January 2016                          CHRT(1)