schedutils/chrt.1

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   3 .\" Copyright (C) 2004 Robert Love
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  25 .\" 2002-05-11 Robert Love <rml@tech9.net>
  26 .\"     Initial version
  27 .\"
  28 .TH CHRT "1" "June 2010" "schedutils" "Linux User's Manual"
  29 .SH NAME
  30 chrt \- manipulate real-time attributes of a process
  31 .SH SYNOPSIS
  32 .B chrt
  33 .RI [ options ]\  prio
  34 .IR command\  [ arg ]...
  35 .br
  36 .B chrt
  37 .RI [ options ]
  38 .B \-p
  39 .RI [ prio ]\  pid
  40 .SH DESCRIPTION
  41 .PP
  42 .BR chrt (1)
  43 sets or retrieves the real-time scheduling attributes of an existing PID, or
  44 runs COMMAND with the given attributes.  Both policy (one of
  45 .BR SCHED_OTHER ,
  46 .BR SCHED_FIFO ,
  47 .BR SCHED_RR ,
  48 .BR SCHED_BATCH ,
  49 or
  50 .BR SCHED_IDLE )
  51 and priority can be set and retrieved.
  52 .PP
  53 The
  54 .BR SCHED_BATCH
  55 policy is supported since Linux 2.6.16. The
  56 .BR SCHED_IDLE
  57 policy is supported since Linux 2.6.23.
  58 .PP
  59 The
  60 .BR SCHED_RESET_ON_FORK
  61 flag for policies SCHED_RR and SCHED_FIFO is supported
  62 since Linux 2.6.31.
  63 .SH OPTIONS
  64 .TP
  65 .B -p, --pid
  66 operate on an existing PID and do not launch a new task
  67 .TP
  68 .B -b, --batch
  69 set scheduling policy to
  70 .BR SCHED_BATCH
  71 (Linux specific)
  72 .TP
  73 .B -f, --fifo
  74 set scheduling policy to
  75 .BR SCHED_FIFO
  76 .TP
  77 .B -i, --idle
  78 set schedulng policy to
  79 .BR SCHED_IDLE
  80 (Linux specific)
  81 .TP
  82 .B -m, --max
  83 show minimum and maximum valid priorities, then exit
  84 .TP
  85 .B -o, --other
  86 set policy scheduling policy to
  87 .BR SCHED_OTHER
  88 .TP
  89 .B -r, --rr
  90 set scheduling policy to
  91 .BR SCHED_RR
  92 (the default)
  93 .TP
  94 .B -R, --reset-on-fork
  95 add
  96 .B SCHED_RESET_ON_FORK
  97 flag to the
  98 .B SCHED_FIFO
  99 or
 100 .B SCHED_RR
 101 scheduling policy (Linux specific)
 102 .TP
 103 .B -v, --verbose
 104 show status information
 105 .TP
 106 .B -h, --help
 107 display usage information and exit
 108 .TP
 109 .B -V, --version
 110 display version information and exit
 111 .SH USAGE
 112 .TP
 113 The default behavior is to run a new command::
 114 chrt prio command [arguments]
 115 .TP
 116 You can also retrieve the real-time attributes of an existing task:
 117 chrt -p pid
 118 .TP
 119 Or set them:
 120 chrt -p prio pid
 121 .SH PERMISSIONS
 122 A user must possess
 123 .BR CAP_SYS_NICE
 124 to change the scheduling attributes of a process.  Any user can retrieve the
 125 scheduling information.
 126 .SH NOTES
 127 Only
 128 .BR SCHED_FIFO ,
 129 .BR SCHED_OTHER
 130 and
 131 .BR SCHED_RR
 132 are part of POSIX 1003.1b Process Scheduling. The other scheduling attributes
 133 may be ignored on some systems.
 134 .SH AUTHOR
 135 Written by Robert M. Love.
 136 .SH COPYRIGHT
 137 Copyright \(co 2004 Robert M. Love
 138 .br
 139 This is free software; see the source for copying conditions.  There is NO
 140 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 141 .SH "SEE ALSO"
 142 .BR taskset (1),
 143 .BR nice (1),
 144 .BR renice (1)
 145 .sp
 146 See
 147 .BR sched_setscheduler (2)
 148 for a description of the Linux scheduling scheme.
 149 .SH AVAILABILITY
 150 The chrt command is part of the util-linux-ng package and is available from
 151 ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.