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systemd/man/oomd.conf.xml

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man: document systemd-oomd and related items
2020-09-09 11:04:36 +03:00
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
man: use same version in public and system ident.
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
license: LGPL-2.1+ -> LGPL-2.1-or-later
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
man: document systemd-oomd and related items
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<refentry id="oomd.conf" conditional='ENABLE_OOMD'
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>oomd.conf</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>oomd.conf</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>oomd.conf</refname>
<refname>oomd.conf.d</refname>
<refpurpose>Global <command>systemd-oomd</command> configuration files</refpurpose>
</refnamediv>
<refsynopsisdiv>
man: use <simplelist> for file lists in synopsis With <para><filename>…</filename></para>, we get a separate "paragraph" for each line, i.e. entries separated by empty lines. This uses up a lot of space and was only done because docbook makes it hard to insert a newline. In some other places, <literallayout> was used, but then we cannot indent the source text (because the whitespace would end up in the final page). We can get the desired result with <simplelist>. With <simplelist> the items are indented in roff output, but not in html output. In some places this looks better then no indentation, and in others it would probably be better to have no indent. But this is a minor issue and we cannot control that. (I didn't convert all spots. There's a bunch of other man pages which have two lines, e.g. an executable and service file, and it doesn't matter there so much.)
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<para><simplelist>
<member><filename>/etc/systemd/oomd.conf</filename></member>
man: document all the new paths
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<member><filename>/run/systemd/oomd.conf</filename></member>
<member><filename>/usr/lib/systemd/oomd.conf</filename></member>
man: use <simplelist> for file lists in synopsis With <para><filename>…</filename></para>, we get a separate "paragraph" for each line, i.e. entries separated by empty lines. This uses up a lot of space and was only done because docbook makes it hard to insert a newline. In some other places, <literallayout> was used, but then we cannot indent the source text (because the whitespace would end up in the final page). We can get the desired result with <simplelist>. With <simplelist> the items are indented in roff output, but not in html output. In some places this looks better then no indentation, and in others it would probably be better to have no indent. But this is a minor issue and we cannot control that. (I didn't convert all spots. There's a bunch of other man pages which have two lines, e.g. an executable and service file, and it doesn't matter there so much.)
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<member><filename>/etc/systemd/oomd.conf.d/*.conf</filename></member>
man: document all the new paths
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<member><filename>/run/systemd/oomd.conf.d/*.conf</filename></member>
man: use <simplelist> for file lists in synopsis With <para><filename>…</filename></para>, we get a separate "paragraph" for each line, i.e. entries separated by empty lines. This uses up a lot of space and was only done because docbook makes it hard to insert a newline. In some other places, <literallayout> was used, but then we cannot indent the source text (because the whitespace would end up in the final page). We can get the desired result with <simplelist>. With <simplelist> the items are indented in roff output, but not in html output. In some places this looks better then no indentation, and in others it would probably be better to have no indent. But this is a minor issue and we cannot control that. (I didn't convert all spots. There's a bunch of other man pages which have two lines, e.g. an executable and service file, and it doesn't matter there so much.)
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<member><filename>/usr/lib/systemd/oomd.conf.d/*.conf</filename></member>
</simplelist></para>
man: document systemd-oomd and related items
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</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>These files configure the various parameters of the
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> userspace
out-of-memory (OOM) killer,
<citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
See <citerefentry><refentrytitle>systemd.syntax</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for a general description of the syntax.</para>
</refsect1>
<xi:include href="standard-conf.xml" xpointer="main-conf" />
<refsect1>
<title>[OOM] Section Options</title>
<para>The following options are available in the [OOM] section:</para>
<variablelist class='config-directives'>
<varlistentry>
oomd: increase accuracy of SwapUsedLimit= to permyriads too oomd.conf has two parameters with fractionals: SwapUsedLimit= and DefaultMemoryPressureLimit=, but one accepts permyriads, the other only percentages, for no apparent reason. One carries the "Percent" in the name, the other doesn't. Let's clean this up: always accept permyriads, and drop the suffix, given that it is misleading. I figure we should internally try to focus on scaling everything relative to UINT32_MAX, and if that isn't in the cards at least 10000, but never permille nor percent unless there's a really really good reason for it (e.g. interface defined by someone else).
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<term><varname>SwapUsedLimit=</varname></term>
oomd: check mem free and swap free before doing a swap-based kill https://bugzilla.redhat.com/show_bug.cgi?id=1974763
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<listitem><para>Sets the limit for memory and swap usage on the system before <command>systemd-oomd</command>
will take action. If the fraction of memory used and the fraction of swap used on the system are both more than
what is defined here, <command>systemd-oomd</command> will act on eligible descendant control groups with swap
usage greater than 5% of total swap, starting from the ones with the highest swap usage. Which
oomd: threshold swap kill candidates to usages of more than 5% In some instances, particularly with swap on zram, swap used will be high while there is still a lot of memory available. FB OOMD handles this by thresholding kills to X% of total swap usage. Let's do the same thing here. Anecdotally with these thresholds and my laptop which is exclusively swap on zram I can sit at 0K / 4G swap free with most of memory free and systemd-oomd doesn't kill anything. Partially addresses aggressive kill behavior from https://bugzilla.redhat.com/show_bug.cgi?id=1941170
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control groups are monitored and what action gets taken depends on what the unit has configured for
oomd: increase accuracy of SwapUsedLimit= to permyriads too oomd.conf has two parameters with fractionals: SwapUsedLimit= and DefaultMemoryPressureLimit=, but one accepts permyriads, the other only percentages, for no apparent reason. One carries the "Percent" in the name, the other doesn't. Let's clean this up: always accept permyriads, and drop the suffix, given that it is misleading. I figure we should internally try to focus on scaling everything relative to UINT32_MAX, and if that isn't in the cards at least 10000, but never permille nor percent unless there's a really really good reason for it (e.g. interface defined by someone else).
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<varname>ManagedOOMSwap=</varname>. Takes a value specified in percent (when suffixed with "%"),
man: add version info This tries to add information about when each option was added. It goes back to version 183. The version info is included from a separate file to allow generating it, which would allow more control on the formatting of the final output.
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permille ("‰") or permyriad ("‱"), between 0% and 100%, inclusive. Defaults to 90%.</para>
man: update version information As I noticed a lot of missing information when trying to implement checking for missing info. I reimplemented the version information script to be more robust, and here is the result. Follow up to ec07c3c80b2b1bfa6788500202006ff85f5ae4f4
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<xi:include href="version-info.xml" xpointer="v247"/></listitem>
man: document systemd-oomd and related items
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</varlistentry>
<varlistentry>
oom: rework *MemoryPressureLimit= properties to have 1/10000 precision Requested in https://github.com/systemd/systemd/pull/15206#discussion_r505506657, preserve the full granularity for memory pressure limits (permyriad) instead of capping out at percent.
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<term><varname>DefaultMemoryPressureLimit=</varname></term>
man: document systemd-oomd and related items
2020-09-09 11:04:36 +03:00
oomd: increase accuracy of SwapUsedLimit= to permyriads too oomd.conf has two parameters with fractionals: SwapUsedLimit= and DefaultMemoryPressureLimit=, but one accepts permyriads, the other only percentages, for no apparent reason. One carries the "Percent" in the name, the other doesn't. Let's clean this up: always accept permyriads, and drop the suffix, given that it is misleading. I figure we should internally try to focus on scaling everything relative to UINT32_MAX, and if that isn't in the cards at least 10000, but never permille nor percent unless there's a really really good reason for it (e.g. interface defined by someone else).
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<listitem><para>Sets the limit for memory pressure on the unit's control group before
<command>systemd-oomd</command> will take action. A unit can override this value with
<varname>ManagedOOMMemoryPressureLimit=</varname>. The memory pressure for this property represents
the fraction of time in a 10 second window in which all tasks in the control group were delayed. For
each monitored control group, if the memory pressure on that control group exceeds the limit set for
longer than the duration set by <varname>DefaultMemoryPressureDurationSec=</varname>,
<command>systemd-oomd</command> will act on eligible descendant control groups, starting from the
ones with the most reclaim activity to the least reclaim activity. Which control groups are monitored
and what action gets taken depends on what the unit has configured for
<varname>ManagedOOMMemoryPressure=</varname>. Takes a fraction specified in the same way as
man: add version info This tries to add information about when each option was added. It goes back to version 183. The version info is included from a separate file to allow generating it, which would allow more control on the formatting of the final output.
2023-08-22 19:52:36 +03:00
<varname>SwapUsedLimit=</varname> above. Defaults to 60%.</para>
man: update version information As I noticed a lot of missing information when trying to implement checking for missing info. I reimplemented the version information script to be more robust, and here is the result. Follow up to ec07c3c80b2b1bfa6788500202006ff85f5ae4f4
2023-09-18 18:03:38 +03:00
<xi:include href="version-info.xml" xpointer="v247"/></listitem>
man: document systemd-oomd and related items
2020-09-09 11:04:36 +03:00
</varlistentry>
oom: make memory pressure duration configurable through oomd.conf
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<varlistentry>
<term><varname>DefaultMemoryPressureDurationSec=</varname></term>
oomd: increase accuracy of SwapUsedLimit= to permyriads too oomd.conf has two parameters with fractionals: SwapUsedLimit= and DefaultMemoryPressureLimit=, but one accepts permyriads, the other only percentages, for no apparent reason. One carries the "Percent" in the name, the other doesn't. Let's clean this up: always accept permyriads, and drop the suffix, given that it is misleading. I figure we should internally try to focus on scaling everything relative to UINT32_MAX, and if that isn't in the cards at least 10000, but never permille nor percent unless there's a really really good reason for it (e.g. interface defined by someone else).
2021-02-17 19:56:26 +03:00
<listitem><para>Sets the amount of time a unit's control group needs to have exceeded memory pressure
limits before <command>systemd-oomd</command> will take action. Memory pressure limits are defined by
oom: rework *MemoryPressureLimit= properties to have 1/10000 precision Requested in https://github.com/systemd/systemd/pull/15206#discussion_r505506657, preserve the full granularity for memory pressure limits (permyriad) instead of capping out at percent.
2021-02-03 01:16:03 +03:00
<varname>DefaultMemoryPressureLimit=</varname> and <varname>ManagedOOMMemoryPressureLimit=</varname>.
man: add version info This tries to add information about when each option was added. It goes back to version 183. The version info is included from a separate file to allow generating it, which would allow more control on the formatting of the final output.
2023-08-22 19:52:36 +03:00
Must be set to 0, or at least 1 second. Defaults to 30 seconds when unset or 0.</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
oom: make memory pressure duration configurable through oomd.conf
2021-01-24 11:16:19 +03:00
</varlistentry>
man: document systemd-oomd and related items
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</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
man: use <simplelist> for 'See also' sections This is just a slight markup improvement; there should be no difference in rendering.
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<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>oomctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
</simplelist></para>
man: document systemd-oomd and related items
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</refsect1>
</refentry>
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