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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-<!-- SPDX-License-Identifier: LGPL-2.1+ -->
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd.resource-control" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
</varlistentry>
<varlistentry>
- <term><varname>MemoryMin=<replaceable>bytes</replaceable></varname></term>
+ <term><varname>MemoryMin=<replaceable>bytes</replaceable></varname>, <varname>MemoryLow=<replaceable>bytes</replaceable></varname></term>
<listitem>
- <para>Specify the memory usage protection of the executed processes in this unit. If the memory usages of
- this unit and all its ancestors are below their minimum boundaries, this unit's memory won't be reclaimed.</para>
-
- <para>Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is
- parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a
- percentage value may be specified, which is taken relative to the installed physical memory on the
- system. If assigned the special value <literal>infinity</literal>, all available memory is protected, which may be
- useful in order to always inherit all of the protection afforded by ancestors.
- This controls the <literal>memory.min</literal> control group attribute. For details about this
- control group attribute, see <ulink
- url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para>
-
- <para>This setting is supported only if the unified control group hierarchy is used and disables
- <varname>MemoryLimit=</varname>.</para>
-
- <para>Units may have their children use a default <literal>memory.min</literal> value by specifying
- <varname>DefaultMemoryMin=</varname>, which has the same semantics as <varname>MemoryMin=</varname>. This setting
- does not affect <literal>memory.min</literal> in the unit itself.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>MemoryLow=<replaceable>bytes</replaceable></varname></term>
-
- <listitem>
- <para>Specify the best-effort memory usage protection of the executed processes in this unit. If the memory
- usages of this unit and all its ancestors are below their low boundaries, this unit's memory won't be
- reclaimed as long as memory can be reclaimed from unprotected units.</para>
+ <para>Specify the memory usage protection of the executed processes in this unit.
+ When reclaiming memory, the unit is treated as if it was using less memory resulting in memory
+ to be preferentially reclaimed from unprotected units.
+ Using <varname>MemoryLow=</varname> results in a weaker protection where memory may still
+ be reclaimed to avoid invoking the OOM killer in case there is no other reclaimable memory.</para>
+ <para>
+ For a protection to be effective, it is generally required to set a corresponding
+ allocation on all ancestors, which is then distributed between children
+ (with the exception of the root slice).
+ Any <varname>MemoryMin=</varname> or <varname>MemoryLow=</varname> allocation that is not
+ explicitly distributed to specific children is used to create a shared protection for all children.
+ As this is a shared protection, the children will freely compete for the memory.</para>
<para>Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is
parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a
percentage value may be specified, which is taken relative to the installed physical memory on the
system. If assigned the special value <literal>infinity</literal>, all available memory is protected, which may be
useful in order to always inherit all of the protection afforded by ancestors.
- This controls the <literal>memory.low</literal> control group attribute. For details about this
- control group attribute, see <ulink
+ This controls the <literal>memory.min</literal> or <literal>memory.low</literal> control group attribute.
+
For details about this control group attribute, see <ulink
url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para>
<para>This setting is supported only if the unified control group hierarchy is used and disables
<varname>MemoryLimit=</varname>.</para>
- <para>Units may have their children use a default <literal>memory.low</literal> value by specifying
- <varname>DefaultMemoryLow=</varname>, which has the same semantics as <varname>MemoryLow=</varname>. This setting
- does not affect <literal>memory.low</literal> in the unit itself.</para>
+ <para>Units may have their children use a default <literal>memory.min</literal> or
+ <literal>memory.low</literal> value by specifying <varname>DefaultMemoryMin=</varname> or
+ <varname>DefaultMemoryLow=</varname>, which has the same semantics as
+ <varname>MemoryMin=</varname> and <varname>MemoryLow=</varname>.
+ This setting does not affect <literal>memory.min</literal> or <literal>memory.low</literal>
+ in the unit itself.
+ Using it to set a default child allocation is only useful on kernels older than 5.7,
+ which do not support the <literal>memory_recursiveprot</literal> cgroup2 mount option.</para>
</listitem>
</varlistentry>
<xi:include href="supported-controllers.xml" xpointer="controllers-text" />
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term><varname>ManagedOOMSwap=auto|kill</varname></term>
+ <term><varname>ManagedOOMMemoryPressure=auto|kill</varname></term>
+
+ <listitem>
+ <para>Specifies how
+ <citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ will act on this unit's cgroups. Defaults to <option>auto</option>.</para>
+
+ <para>When set to <option>kill</option>, <command>systemd-oomd</command> will actively monitor this unit's
+ cgroup metrics to decide whether it needs to act. If the cgroup passes the limits set by
+ <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> or its
+ overrides, <command>systemd-oomd</command> will send a <constant>SIGKILL</constant> to all of the processes
+ under the chosen candidate cgroup. Note that only descendant cgroups can be eligible candidates for killing;
+ the unit that set its property to <option>kill</option> is not a candidate (unless one of its ancestors set
+ their property to <option>kill</option>). You can find more details on candidates and kill behavior at
+ <citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ and <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Setting
+ either of these properties to <option>kill</option> will also automatically acquire
+ <varname>After=</varname> and <varname>Wants=</varname> dependencies on
+ <filename>systemd-oomd.service</filename> unless <varname>DefaultDependencies=no</varname>.
+ </para>
+
+ <para>When set to <option>auto</option>, <command>systemd-oomd</command> will not actively use this cgroup's
+ data for monitoring and detection. However, if an ancestor cgroup has one of these properties set to
+ <option>kill</option>, a unit with <option>auto</option> can still be an eligible candidate for
+ <command>systemd-oomd</command> to act on.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ManagedOOMMemoryPressureLimitPercent=</varname></term>
+
+ <listitem>
+ <para>Overrides the default memory pressure limit set by
+ <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for this unit
+ (cgroup). Takes a percentage value between 0% and 100%, inclusive. This property is ignored unless
+ <varname>ManagedOOMMemoryPressure=</varname><option>kill</option>. Defaults to 0%, which means use the
+ default set by <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para>
+ </listitem>
+ </varlistentry>
</variablelist>
</refsect1>
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
The documentation for control groups and specific controllers in the Linux kernel:
<ulink url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html">Control Groups v2</ulink>.
</para>
projects / thirdparty / systemd.git / blobdiff