1CHRT(1)                          User Commands                         CHRT(1)
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NAME

6       chrt - manipulate the real-time attributes of a process
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SYNOPSIS

9       chrt [options] priority command [argument...]
10       chrt [options] -p [priority] pid
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DESCRIPTION

13       chrt sets or retrieves the real-time scheduling attributes of an exist‐
14       ing pid, or runs command with the given attributes.
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POLICIES

18       -o, --other
19              Set scheduling policy to SCHED_OTHER.  This is the default Linux
20              scheduling policy.
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22       -f, --fifo
23              Set scheduling policy to SCHED_FIFO.
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25       -r, --rr
26              Set  scheduling  policy to SCHED_RR.  When no policy is defined,
27              the SCHED_RR is used as the default.
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29       -b, --batch
30              Set scheduling policy to SCHED_BATCH (Linux-specific,  supported
31              since 2.6.16).  The priority argument has to be set to zero.
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33       -i, --idle
34              Set  scheduling  policy to SCHED_IDLE (Linux-specific, supported
35              since 2.6.23).  The priority argument has to be set to zero.
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37       -d, --deadline
38              Set scheduling policy to  SCHED_DEADLINE  (Linux-specific,  sup‐
39              ported  since  3.14).   The  priority  argument has to be set to
40              zero.    See   also   --sched-runtime,   --sched-deadline    and
41              --sched-period.   The  relation  between the options required by
42              the kernel is runtime <= deadline <= period.  chrt copies period
43              to deadline if --sched-deadline is not specified and deadline to
44              runtime if --sched-runtime is not specified.  It means  that  at
45              least --sched-period has to be specified.  See sched(7) for more
46              details.
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SCHEDULING OPTIONS

50       -T, --sched-runtime nanoseconds
51              Specifies runtime parameter for  SCHED_DEADLINE  policy  (Linux-
52              specific).
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54       -P, --sched-period nanoseconds
55              Specifies period parameter for SCHED_DEADLINE policy (Linux-spe‐
56              cific).
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58       -D, --sched-deadline nanoseconds
59              Specifies deadline parameter for SCHED_DEADLINE  policy  (Linux-
60              specific).
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62       -R, --reset-on-fork
63              Add  SCHED_RESET_ON_FORK  flag  to  the  SCHED_FIFO  or SCHED_RR
64              scheduling policy (Linux-specific, supported since 2.6.31).
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OPTIONS

68       -a, --all-tasks
69              Set or retrieve the  scheduling  attributes  of  all  the  tasks
70              (threads) for a given PID.
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72       -m, --max
73              Show minimum and maximum valid priorities, then exit.
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75       -p, --pid
76              Operate on an existing PID and do not launch a new task.
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78       -v, --verbose
79              Show status information.
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81       -V, --version
82              Display version information and exit.
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84       -h, --help
85              Display help text and exit.
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USAGE

88       The default behavior is to run a new command:
89              chrt priority command [arguments]
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91       You can also retrieve the real-time attributes of an existing task:
92              chrt -p pid
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94       Or set them:
95              chrt -r -p priority pid
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PERMISSIONS

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

103       Only SCHED_FIFO, SCHED_OTHER and SCHED_RR are  part  of  POSIX  1003.1b
104       Process  Scheduling.  The other scheduling attributes may be ignored on
105       some systems.
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107       Linux' default scheduling policy is SCHED_OTHER.
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AUTHORS

110       Robert Love ⟨rml@tech9.net⟩
111       Karel Zak ⟨kzak@redhat.com⟩
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SEE ALSO

114       nice(1), renice(1), taskset(1), sched(7)
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116       See sched_setscheduler(2) for a description  of  the  Linux  scheduling
117       scheme.
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AVAILABILITY

120       The  chrt  command  is  part of the util-linux package and is available
121       from https://www.kernel.org/pub/linux/utils/util-linux/.
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125util-linux                       January 2016                          CHRT(1)