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