2 .\" Copyright (c) 1994, Henrik Vestergaard Draboel
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
8 .\" 1. Redistributions of source code must retain the above copyright
9 .\" notice, this list of conditions and the following disclaimer.
10 .\" 2. Redistributions in binary form must reproduce the above copyright
11 .\" notice, this list of conditions and the following disclaimer in the
12 .\" documentation and/or other materials provided with the distribution.
13 .\" 3. All advertising materials mentioning features or use of this software
14 .\" must display the following acknowledgement:
15 .\" This product includes software developed by Henrik Vestergaard Draboel.
16 .\" 4. The name of the author may not be used to endorse or promote products
17 .\" derived from this software without specific prior written permission.
19 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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24 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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31 .\" $FreeBSD: src/usr.sbin/rtprio/rtprio.1,v 1.19.2.4 2002/06/21 16:42:31 charnier Exp $
32 .\" $DragonFly: src/usr.sbin/rtprio/rtprio.1,v 1.3 2004/03/11 12:29:00 hmp Exp $
40 .Nd execute, examine or modify a utility's or process's realtime
41 or idletime scheduling priority
63 utility is used for controlling realtime process scheduling.
67 utility is used for controlling idletime process scheduling, and can be called
68 with the same options as
71 A process with a realtime priority is not subject to priority
72 degradation, and will only be preempted by another process of equal or
73 higher realtime priority.
75 A process with an idle priority will run only when no other
76 process is runnable and then only if its idle priority is equal or
77 greater than all other runnable idle priority processes.
83 when called without arguments will return the realtime priority
84 of the current process.
88 is called with 1 argument, it will return the realtime priority
89 of the process with the specified
94 is specified, the process or program is run at that realtime priority.
97 is specified, the process or program is run as a normal (non-realtime)
102 is specified, the process with the process identifier
104 will be modified, else if
106 is specified, that program is run with its arguments.
109 is an integer between 0 and RTP_PRIO_MAX (usually 31). 0 is the
113 of 0 means "the current process".
115 Only root is allowed to set realtime or idle priority for a process.
119 execute a command, the exit value is that of the command executed.
122 exits 0 on success, and 1 for all other errors.
124 To see which realtime priority the current process is at:
125 .Bd -literal -offset indent -compact
129 To see which realtime priority of process
131 .Bd -literal -offset indent -compact
137 at the lowest realtime priority:
138 .Bd -literal -offset indent -compact
142 To change the realtime priority of process
146 .Bd -literal -offset indent -compact
147 .Sy "rtprio 16 -1423"
152 without realtime priority:
153 .Bd -literal -offset indent -compact
154 .Sy "rtprio -t tcpdump"
157 To change the realtime priority of process
161 (non-realtime/normal priority):
162 .Bd -literal -offset indent -compact
163 .Sy "rtprio -t -1423"
166 To make depend while not disturbing other machine usage:
167 .Bd -literal -offset indent -compact
168 .Sy "idprio 31 make depend"
182 but is similar to the HP-UX version.
184 You can lock yourself out of the system by placing a cpu-heavy
185 process in a realtime priority.
187 There is no way to set/view the realtime priority of process 0
193 no way to ensure that a process page is present in memory therefore
194 the process may be stopped for pagein (see
200 system calls are currently never preempted, therefore non-realtime
201 processes can starve realtime processes, or idletime processes can
202 starve normal priority processes.
205 .An Henrik Vestergaard Draboel Aq hvd@terry.ping.dk
206 is the original author.
208 implementation was substantially rewritten by