NAME

reniced - renice running processes based on regular expressions

SYNOPSIS

reniced [-h] [-v] [-o format] [configfile]

OVERVIEW

reniced takes a list of regular expressions, looks for processes (and threads) matching them and renices the processes to given values. reniced can also change io priorities.

DESCRIPTION

On start, reniced reads a configuration file. It consists of nice values and regular expressions.

It then scans the process table using the ps(1) command. Whenever a process name from the CMD column matches a regular expression, that process is reniced to the given value. If a process matches multiple regular expressions, all rule matches are executed in order and the last match wins.

When run as root, reniced will scan all processes (`ps H -e`). When run as a user, renice only scans the user's processes (`ps H --user`).

Switches

• -h

  This prints the version number, a short help text and exits without doing anything.

• -n

  This activates no-op mode. No actions are taken but everything that would be done is written to stdout.

• -v

  This activates verbose mode. Error messages, some statistics and all renice actions are printed to stdout.

• -o format

  Set the ps(1) output format to filter on. The default format is comm. See the -o parameter in the ps(1) manpage for details.

• configfile

  This reads the regular expressions from an alternate configfile.

  The default location of the configfile is /etc/reniced.conf if reniced is run as root, ~/.reniced otherwise.

Configuration file format

The configuration file is composed of single lines. Empty lines and lines starting with a # are ignored.

Every line must consist of a command followed by a whitespace and a Perl regular expression.

The regular expression is matched against the ps(1) output. For every matched process the command is executed.

A command generally takes the form of a character followed by a number. Multiple commands can be given simultaneously with no spaces inbetween. Sometimes the number is optional.

Command characters

• n

  Sets the nice value of a process. Must be followed by a number, usually within the range of -20 to 19.

  For backwards compatibility a n at the beginning of the command can be left out (if the command starts with a number it is treated as a nice value).

• r

  Sets the io priority to the realtime scheduling class. The optional number is treated as class data (typically 0-7, lower being higher priority).

• b

  Sets the io priority to the best-effort scheduling class. The optional number is treated as class data (typically 0-7, lower being higher priority).

• i

  Sets the io priority to the idle scheduling class. No number needs to be given as the idle scheduling class ignores the class data value.

• o

  Sets the OOM killer adjustment in /proc/$PID/oom_adj to the given number. (Internally, /proc/$PID/oom_score_adj will be used when available, but for backwards compatibility this value is still expected the in old oom_adj format and will be converted automatically.)

Examples

• 5 ^bash

  gives currently running bash shells a nice value of 5

• b2 ^tar

  sets currently running tar-processes to io priority best-effort within class 2

• i torrent

  sets currently running torrent-like applications to io priority idle

• n-10r4 seti

  gives currently running seti-processes a nice value of -10 and sets them to realtime io priority in class 4

MODULES NEEDED

use BSD::Resource;

This module can be obtained from http://www.cpan.org.

PROGRAMS NEEDED

ps
ionice

ionice is only needed if you want to change io priority. It can be obtained from http://rlove.org/schedutils/.

You also need a suitable kernel and scheduler, e.g. Linux 2.6 with CFQ.

LIMITATIONS

The purpose of reniced is to renice long running server processes (hence the d for daemon in it's name).

Selecting and renicing processes it not atomic: There is a small gap between scanning the process list and renicing the processes. If you target short-lived processes with your regular expressions, reniced might try to act on a process that is already gone. In the worst case it might renice a new process that got the same process id as the already ended process that was matched.

BUGS

reniced can run without the BSD::Resource module. In this case, the PRIO_PROCESS is set to 0. This works on Linux 2.6.11 i686 but it could break on other systems. Installing BSD::Resource is the safer way.

Be careful using realtime priorities, don't starve other tasks.

Please report bugs to <mitch@cgarbs.de>.

AUTHOR

reniced was written by Christian Garbs <mitch@cgarbs.de>.

COPYRIGHT

reniced is Copyright (C) 2005, 2020 by Christian Garbs. It is licensed under the GNU GPL v2 or later.

AVAILABILITY

Look for updates at https://github.com/mmitch/reniced.

SEE ALSO

ionice(1), renice(1), ps(1)