116 lines
3.1 KiB
Groff
116 lines
3.1 KiB
Groff
.\" Automatically generated by Pandoc 1.17.2
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.\"
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.TH "nohang" "8" "" "" "Linux System Administrator\[aq]s Manual"
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.hy
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.SH NAME
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.PP
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nohang \- A sophisticated low memory handler
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.SH SYNOPSIS
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.PP
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\f[B]nohang\f[] [\f[B]OPTION\f[]]...
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.SH DESCRIPTION
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.PP
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nohang is a highly configurable daemon for Linux which is able to
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correctly prevent out of memory (OOM) and keep system responsiveness in
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low memory conditions.
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.SH REQUIREMENTS
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.SS For basic usage:
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.IP \[bu] 2
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Linux (>= 3.14, since MemAvailable appeared in /proc/meminfo)
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.IP \[bu] 2
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Python (>= 3.3)
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.SS To respond to PSI metrics (optional):
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.IP \[bu] 2
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Linux (>= 4.20) with CONFIG_PSI=y
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.SS To show GUI notifications (optional):
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.IP \[bu] 2
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notification server (most of desktop environments use their own
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implementations)
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.IP \[bu] 2
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libnotify (Arch Linux, Fedora, openSUSE) or libnotify\-bin (Debian
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GNU/Linux, Ubuntu)
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.IP \[bu] 2
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sudo if nohang started with UID=0.
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.SH OPTIONS
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.SS \-h, \-\-help
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.PP
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show this help message and exit
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.SS \-v, \-\-version
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.PP
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show version of installed package and exit
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.SS \-m, \-\-memload
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.PP
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consume memory until 40 MiB (MemAvailable + SwapFree) remain free, and
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terminate the process
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.SS \-c CONFIG, \-\-config CONFIG
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.PP
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path to the config file.
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This should only be used with one of the following options: \-\-monitor,
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\-\-tasks, \-\-check
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.SS \-\-check
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.PP
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check and show the configuration and exit.
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This should only be used with \-c/\-\-config CONFIG option
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.SS \-\-monitor
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.PP
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start monitoring.
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This should only be used with \-c/\-\-config CONFIG option
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.SS \-\-tasks
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.PP
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show tasks state and exit.
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This should only be used with \-c/\-\-config CONFIG option
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.SH HOW TO CONFIGURE
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.PP
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The program can be configured by editing the config file.
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The configuration includes the following sections:
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.IP \[bu] 2
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Memory levels to respond to as an OOM threat
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.IP \[bu] 2
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Response on PSI memory metrics
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.IP \[bu] 2
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The frequency of checking the level of available memory (and CPU usage)
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.IP \[bu] 2
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The prevention of killing innocent victims
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.IP \[bu] 2
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Impact on the badness of processes via matching their names, cmdlines
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and UIDs with regular expressions
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.IP \[bu] 2
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The execution of a specific command or sending any signal instead of
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sending the SIGTERM signal
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.IP \[bu] 2
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GUI notifications:
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.RS 2
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.IP \[bu] 2
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notifications of corrective actions taken
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.IP \[bu] 2
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low memory warnings
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.RE
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.IP \[bu] 2
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Verbosity
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.IP \[bu] 2
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Misc
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.PP
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Just read the description of the parameters and edit the values.
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Restart the daemon to apply the changes.
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.SH HOW TO TEST
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.PP
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The safest way is to run \f[B]nohang \-\-memload\f[].
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This causes memory consumption, and the process will exits before OOM
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occurs.
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Another way is to run \f[B]tail /dev/zero\f[].
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This causes fast memory comsumption and causes OOM at the end.
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If testing occurs while nohang is running, these processes should be
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terminated before OOM occurs.
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.SH LOGGING
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.PP
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To view the latest entries in the log (for systemd users):
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.PP
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$ \f[B]sudo journalctl \-eu nohang.service\f[]
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.PP
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or
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.PP
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$ \f[B]sudo journalctl \-eu nohang\-desktop.service\f[]
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.PP
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You can also enable \f[B]separate_log\f[] in the config to logging in
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\f[B]/var/log/nohang/nohang.log\f[].
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