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1 | .\" chrt(1) manpage |
2 | .\" | |
3 | .\" Copyright (C) 2004 Robert Love | |
5b033bfd | 4 | .\" Copyright (C) 2015 Karel Zak <kzak@redhat.com> |
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5 | .\" |
6 | .\" This is free documentation; you can redistribute it and/or | |
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7 | .\" modify it under the terms of the GNU General Public License, |
8 | .\" version 2, as published by the Free Software Foundation. | |
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9 | .\" |
10 | .\" The GNU General Public License's references to "object code" | |
11 | .\" and "executables" are to be interpreted as the output of any | |
12 | .\" document formatting or typesetting system, including | |
13 | .\" intermediate and printed output. | |
14 | .\" | |
15 | .\" This manual is distributed in the hope that it will be useful, | |
16 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | .\" GNU General Public License for more details. | |
19 | .\" | |
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20 | .\" You should have received a copy of the GNU General Public License along |
21 | .\" with this program; if not, write to the Free Software Foundation, Inc., | |
22 | .\" 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
48d7b13a | 23 | .\" |
5b033bfd | 24 | .TH CHRT 1 "January 2016" "util-linux" "User Commands" |
48d7b13a | 25 | .SH NAME |
232dc924 | 26 | chrt \- manipulate the real-time attributes of a process |
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27 | .SH SYNOPSIS |
28 | .B chrt | |
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29 | [options] |
30 | .IR priority\ command\ [ argument ...] | |
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31 | .br |
32 | .B chrt | |
42f15e98 | 33 | [options] |
5ebbcdf9 | 34 | .B \-p |
42f15e98 | 35 | .RI [ priority ]\ pid |
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36 | .SH DESCRIPTION |
37 | .PP | |
232dc924 | 38 | .B chrt |
397a5114 | 39 | sets or retrieves the real-time scheduling attributes of an existing \fIpid\fR, |
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40 | or runs \fIcommand\fR with the given attributes. |
41 | ||
42 | .SH POLICIES | |
48d7b13a | 43 | .TP |
5b033bfd | 44 | \fB\-o\fR, \fB\-\-other\fR |
8722fc38 | 45 | Set scheduling policy to |
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46 | .BR SCHED_OTHER . |
47 | This is the default Linux scheduling policy. | |
48 | .TP | |
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49 | \fB\-f\fR, \fB\-\-fifo\fR |
50 | Set scheduling policy to \fBSCHED_FIFO\fR. | |
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51 | .TP |
52 | \fB\-r\fR, \fB\-\-rr\fR | |
53 | Set scheduling policy to | |
54 | .BR SCHED_RR . | |
8722fc38 | 55 | When no policy is defined, the |
5b033bfd | 56 | .B SCHED_RR |
8722fc38 | 57 | is used as the default. |
78904e76 | 58 | .TP |
5b033bfd | 59 | \fB\-b\fR, \fB\-\-batch\fR |
397a5114 | 60 | Set scheduling policy to |
42f15e98 | 61 | .B SCHED_BATCH |
8722fc38 | 62 | (Linux-specific, supported since 2.6.16). The priority argument has to be set to zero. |
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63 | .TP |
64 | \fB\-i\fR, \fB\-\-idle\fR | |
65 | Set scheduling policy to | |
66 | .B SCHED_IDLE | |
8722fc38 | 67 | (Linux-specific, supported since 2.6.23). The priority argument has to be set to zero. |
48d7b13a | 68 | .TP |
1a7e6395 | 69 | .BR -d ,\ --deadline |
8722fc38 | 70 | Set scheduling policy to |
0bb7e904 | 71 | .B SCHED_DEADLINE |
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72 | (Linux-specific, supported since 3.14). The priority argument has to be set to zero. |
73 | See also \fB\-\-sched\-runtime\fR, \fB\-\-sched\-deadline\fR and | |
74 | \fB\-\-sched\-period\fR. The relation between the options required by the kernel is | |
5b033bfd | 75 | runtime <= deadline <= period. |
1a7e6395 | 76 | .B chrt |
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77 | copies \fIperiod\fR to \fIdeadline\fR if \fB\-\-sched\-deadline\fR is not specified and |
78 | \fIdeadline\fR to \fIruntime\fR if \fB\-\-sched\-runtime\fR is not specified. | |
79 | It means that at least \fB\-\-sched\-period\fR has to be specified. See | |
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80 | .BR sched (7) |
81 | for more details. | |
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82 | |
83 | .SH "SCHEDULING OPTIONS" | |
1a7e6395 | 84 | .TP |
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85 | \fB\-T\fR, \fB\-\-sched\-runtime\fR \fInanoseconds\fR |
86 | Specifies runtime parameter for SCHED_DEADLINE policy (Linux-specific). | |
48d7b13a | 87 | .TP |
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88 | \fB\-P\fR, \fB\-\-sched\-period\fR \fInanoseconds\fR |
89 | Specifies period parameter for SCHED_DEADLINE policy (Linux-specific). | |
397a5114 | 90 | .TP |
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91 | \fB\-D\fR, \fB\-\-sched\-deadline\fR \fInanoseconds\fR |
92 | Specifies deadline parameter for SCHED_DEADLINE policy (Linux-specific). | |
48d7b13a | 93 | .TP |
5b033bfd | 94 | \fB\-R\fR, \fB\-\-reset-on-fork\fR |
397a5114 | 95 | Add |
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96 | .B SCHED_RESET_ON_FORK |
97 | flag to the | |
98 | .B SCHED_FIFO | |
99 | or | |
100 | .B SCHED_RR | |
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101 | scheduling policy (Linux-specific, supported since 2.6.31). |
102 | ||
103 | .SH OPTIONS | |
5f719971 | 104 | .TP |
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105 | .BR -a ,\ --all-tasks |
106 | Set or retrieve the scheduling attributes of all the tasks (threads) for a | |
107 | given PID. | |
1a7e6395 | 108 | .TP |
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109 | .BR -m ,\ --max |
110 | Show minimum and maximum valid priorities, then exit. | |
1a7e6395 | 111 | .TP |
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112 | .BR -p ,\ --pid |
113 | Operate on an existing PID and do not launch a new task. | |
1a7e6395 | 114 | .TP |
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115 | .BR -v ,\ --verbose |
116 | Show status information. | |
48d7b13a | 117 | .TP |
42f15e98 | 118 | .BR -V ,\ --version |
397a5114 | 119 | Display version information and exit. |
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120 | .TP |
121 | .BR -h ,\ --help | |
122 | Display help text and exit. | |
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123 | .SH USAGE |
124 | .TP | |
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125 | The default behavior is to run a new command: |
126 | .B chrt | |
42f15e98 | 127 | .I priority |
397a5114 | 128 | .IR command\ [ arguments ] |
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129 | .TP |
130 | You can also retrieve the real-time attributes of an existing task: | |
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131 | .B chrt \-p |
132 | .I pid | |
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133 | .TP |
134 | Or set them: | |
fdf8fb1c | 135 | .B chrt \-r \-p |
42f15e98 | 136 | .I priority pid |
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137 | .SH PERMISSIONS |
138 | A user must possess | |
0bb7e904 | 139 | .B CAP_SYS_NICE |
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140 | to change the scheduling attributes of a process. Any user can retrieve the |
141 | scheduling information. | |
5b033bfd | 142 | |
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143 | .SH NOTES |
144 | Only | |
145 | .BR SCHED_FIFO , | |
0bb7e904 | 146 | .B SCHED_OTHER |
40bc2ab5 | 147 | and |
0bb7e904 | 148 | .B SCHED_RR |
8722fc38 | 149 | are part of POSIX 1003.1b Process Scheduling. The other scheduling attributes |
40bc2ab5 | 150 | may be ignored on some systems. |
fdf8fb1c | 151 | .P |
8722fc38 | 152 | Linux' default scheduling policy is |
fdf8fb1c | 153 | .BR SCHED_OTHER . |
42f15e98 | 154 | .SH SEE ALSO |
48d7b13a | 155 | .BR nice (1), |
5b033bfd | 156 | .BR renice (1), |
f053ff1e | 157 | .BR taskset (1), |
1a7e6395 | 158 | .BR sched (7) |
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159 | .sp |
160 | See | |
161 | .BR sched_setscheduler (2) | |
162 | for a description of the Linux scheduling scheme. | |
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163 | .SH AUTHORS |
164 | .UR rml@tech9.net | |
165 | Robert Love | |
166 | .UE | |
167 | .br | |
168 | .UR kzak@redhat.com | |
169 | Karel Zak | |
170 | .UE | |
86d62711 | 171 | .SH AVAILABILITY |
601d12fb | 172 | The chrt command is part of the util-linux package and is available from |
d673b74e | 173 | https://www.kernel.org/pub/linux/utils/util-linux/. |