CHRT(1)                         User Commands                        CHRT(1)

NAME         top

       chrt - manipulate the real-time attributes of a process

SYNOPSIS         top

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

DESCRIPTION         top

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

POLICIES         top

       -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         top

       -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         top

       -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         top

       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         top

       A user must possess CAP_SYS_NICE to change the scheduling attributes
       of a process.  Any user can retrieve the scheduling information.

NOTES         top

       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         top

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

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

AUTHORS         top

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

AVAILABILITY         top

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

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.  If you have a
       bug report for this manual page, send it to
       util-linux@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2018-02-02.  (At that time, the date of the most recent commit that
       was found in the repository was 2018-02-01.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

util-linux                      January 2016                         CHRT(1)

Pages that refer to this page: taskset(1),  sched_setattr(2),  sched_setscheduler(2),  sched(7)

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