NAME¶

oomd.conf, oomd.conf.d - Global systemd-oomd configuration files

SYNOPSIS¶

DESCRIPTION¶

These files configure the various parameters of the systemd(1) userspace out-of-memory (OOM) killer, systemd-oomd.service(8). See systemd.syntax(7) for a general description of the syntax.

CONFIGURATION DIRECTORIES AND PRECEDENCE¶

The default configuration is set during compilation, so configuration is only needed when it is necessary to deviate from those defaults. The main configuration file is loaded from one of the listed directories in order of priority, only the first file found is used: /etc/systemd/, /run/systemd/, /usr/local/lib/systemd/ [1], /usr/lib/systemd/. The vendor version of the file contains commented out entries showing the defaults as a guide to the administrator. Local overrides can also be created by creating drop-ins, as described below. The main configuration file can also be edited for this purpose (or a copy in /etc/ if it is shipped under /usr/), however using drop-ins for local configuration is recommended over modifications to the main configuration file.

In addition to the main configuration file, drop-in configuration snippets are read from /usr/lib/systemd/*.conf.d/, /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/. Those drop-ins have higher precedence and override the main configuration file. Files in the *.conf.d/ configuration subdirectories are sorted by their filename in lexicographic order, regardless of in which of the subdirectories they reside. When multiple files specify the same option, for options which accept just a single value, the entry in the file sorted last takes precedence, and for options which accept a list of values, entries are collected as they occur in the sorted files.

When packages need to customize the configuration, they can install drop-ins under /usr/. Files in /etc/ are reserved for the local administrator, who may use this logic to override the configuration files installed by vendor packages. Drop-ins have to be used to override package drop-ins, since the main configuration file has lower precedence. It is recommended to prefix all filenames in those subdirectories with a two-digit number and a dash, to simplify the ordering. This also defines a concept of drop-in priorities to allow OS vendors to ship drop-ins within a specific range lower than the range used by users. This should lower the risk of package drop-ins overriding accidentally drop-ins defined by users. It is recommended to use the range 10-40 for drop-ins in /usr/ and the range 60-90 for drop-ins in /etc/ and /run/, to make sure that local and transient drop-ins take priority over drop-ins shipped by the OS vendor.

To disable a configuration file supplied by the vendor, the recommended way is to place a symlink to /dev/null in the configuration directory in /etc/, with the same filename as the vendor configuration file.

PREKILL EVENT¶

systemd-oomd supports notifying external components before killing a control group. This is done by sending a notification over varlink to all sockets found in /run/systemd/oomd.prekill.hook/ folder. Each socket should implement the io.systemd.oom.Prekill interface. The notification contains the control group path to allow the hook to identify which control group is being killed. This allows external components to perform any necessary cleanup or logging before the control group is terminated. The hook is not intended as a way to avoid the kill, but rather as a notification mechanism. Note that this is a privileged option as, even if it has a timeout, is synchronous and delays the kill, so use with care. The typically preferable mechanism to process memory pressure is to do what MEMORY_PRESSURE[2] describes which is unprivileged, asynchronous and does not delay the kill.

[OOM] SECTION OPTIONS¶

The following options are available in the [OOM] section:

SwapUsedLimit=

DefaultMemoryPressureLimit=

DefaultMemoryPressureDurationSec=

PrekillHookTimeoutSec=

SEE ALSO¶

systemd(1), systemd.resource-control(5), systemd-oomd.service(8), oomctl(1)

NOTES¶

1.

💣💥🧨💥💥💣 Please note that those configuration files must be available at all times. If /usr/local/ is a separate partition, it may not be available during early boot, and must not be used for configuration.

2.

MEMORY_PRESSURE