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diff --git a/man/systemd.resource-control.xml b/man/systemd.resource-control.xml new file mode 100644 index 0000000..42f265c --- /dev/null +++ b/man/systemd.resource-control.xml @@ -0,0 +1,1675 @@ +<?xml version='1.0'?> +<!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-or-later --> + +<refentry id="systemd.resource-control" xmlns:xi="http://www.w3.org/2001/XInclude"> + <refentryinfo> + <title>systemd.resource-control</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>systemd.resource-control</refentrytitle> + <manvolnum>5</manvolnum> + </refmeta> + + <refnamediv> + <refname>systemd.resource-control</refname> + <refpurpose>Resource control unit settings</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <para> + <filename><replaceable>slice</replaceable>.slice</filename>, + <filename><replaceable>scope</replaceable>.scope</filename>, + <filename><replaceable>service</replaceable>.service</filename>, + <filename><replaceable>socket</replaceable>.socket</filename>, + <filename><replaceable>mount</replaceable>.mount</filename>, + <filename><replaceable>swap</replaceable>.swap</filename> + </para> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>Unit configuration files for services, slices, scopes, sockets, mount points, and swap devices share a subset + of configuration options for resource control of spawned processes. Internally, this relies on the Linux Control + Groups (cgroups) kernel concept for organizing processes in a hierarchical tree of named groups for the purpose of + resource management.</para> + + <para>This man page lists the configuration options shared by + those six unit types. See + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for the common options of all unit configuration files, and + <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + and + <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for more information on the specific unit configuration files. The + resource control configuration options are configured in the + [Slice], [Scope], [Service], [Socket], [Mount], or [Swap] + sections, depending on the unit type.</para> + + <para>In addition, options which control resources available to programs + <emphasis>executed</emphasis> by systemd are listed in + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + Those options complement options listed here.</para> + + <refsect2> + <title>Enabling and disabling controllers</title> + + <para>Controllers in the cgroup hierarchy are hierarchical, and resource control is realized by + distributing resource assignments between siblings in branches of the cgroup hierarchy. There is no + need to explicitly <emphasis>enable</emphasis> a cgroup controller for a unit. + <command>systemd</command> will instruct the kernel to enable a controller for a given unit when this + unit has configuration for a given controller. For example, when <varname>CPUWeight=</varname> is set, + the <option>cpu</option> controller will be enabled, and when <varname>TasksMax=</varname> are set, the + <option>pids</option> controller will be enabled. In addition, various controllers may be also be + enabled explicitly via the + <varname>MemoryAccounting=</varname>/<varname>TasksAccounting=</varname>/<varname>IOAccounting=</varname> + settings. Because of how the cgroup hierarchy works, controllers will be automatically enabled for all + parent units and for any sibling units starting with the lowest level at which a controller is enabled. + Units for which a controller is enabled may be subject to resource control even if they don't have any + explicit configuration.</para> + + <para>Setting <varname>Delegate=</varname> enables any delegated controllers for that unit (see below). + The delegatee may then enable controllers for its children as appropriate. In particular, if the + delegatee is <command>systemd</command> (in the <filename>user@.service</filename> unit), it will + repeat the same logic as the system instance and enable controllers for user units which have resource + limits configured, and their siblings and parents and parents' siblings.</para> + + <para>Controllers may be <emphasis>disabled</emphasis> for parts of the cgroup hierarchy with + <varname>DisableControllers=</varname> (see below).</para> + + <example> + <title>Enabling and disabling controllers</title> + + <programlisting> + -.slice + / \ + /-----/ \--------------\ + / \ + system.slice user.slice + / \ / \ + / \ / \ + / \ user@42.service user@1000.service + / \ Delegate= Delegate=yes +a.service b.slice / \ +CPUWeight=20 DisableControllers=cpu / \ + / \ app.slice session.slice + / \ CPUWeight=100 CPUWeight=100 + / \ + b1.service b2.service + CPUWeight=1000 + </programlisting> + + <para>In this hierarchy, the <option>cpu</option> controller is enabled for all units shown except + <filename>b1.service</filename> and <filename>b2.service</filename>. Because there is no explicit + configuration for <filename>system.slice</filename> and <filename>user.slice</filename>, CPU + resources will be split equally between them. Similarly, resources are allocated equally between + children of <filename>user.slice</filename> and between the child slices beneath + <filename>user@1000.service</filename>. Assuming that there is no further configuration of resources + or delegation below slices <filename>app.slice</filename> or <filename>session.slice</filename>, the + <option>cpu</option> controller would not be enabled for units in those slices and CPU resources + would be further allocated using other mechanisms, e.g. based on nice levels. The manager for user + 42 has delegation enabled without any controllers, i.e. it can manipulate its subtree of the cgroup + hierarchy, but without resource control.</para> + + <para>In the slice <filename>system.slice</filename>, CPU resources are split 1:6 for service + <filename>a.service</filename>, and 5:6 for slice <filename>b.slice</filename>, because slice + <filename>b.slice</filename> gets the default value of 100 for <filename>cpu.weight</filename> when + <varname>CPUWeight=</varname> is not set.</para> + + <para><varname>CPUWeight=</varname> setting in service <filename>b2.service</filename> is neutralized + by <varname>DisableControllers=</varname> in slice <filename>b.slice</filename>, so the + <option>cpu</option> controller would not be enabled for services <filename>b1.service</filename> and + <filename>b2.service</filename>, and CPU resources would be further allocated using other mechanisms, + e.g. based on nice levels.</para> + </example> + </refsect2> + + <refsect2> + <title>Setting resource controls for a group of related units</title> + + <para>As described in + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, the + settings listed here may be set through the main file of a unit and drop-in snippets in + <filename index="false">*.d/</filename> directories. The list of directories searched for drop-ins + includes names formed by repeatedly truncating the unit name after all dashes. This is particularly + convenient to set resource limits for a group of units with similar names.</para> + + <para>For example, every user gets their own slice + <filename>user-<replaceable>nnn</replaceable>.slice</filename>. Drop-ins with local configuration that + affect user 1000 may be placed in + <filename index="false">/etc/systemd/system/user-1000.slice</filename>, + <filename index="false">/etc/systemd/system/user-1000.slice.d/*.conf</filename>, but also + <filename index="false">/etc/systemd/system/user-.slice.d/*.conf</filename>. This last directory + applies to all user slices.</para> + </refsect2> + + <para>See the <ulink + url="https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface">New + Control Group Interfaces</ulink> for an introduction on how to make + use of resource control APIs from programs.</para> + </refsect1> + + <refsect1> + <title>Implicit Dependencies</title> + + <para>The following dependencies are implicitly added:</para> + + <itemizedlist> + <listitem><para>Units with the <varname>Slice=</varname> setting set automatically acquire + <varname>Requires=</varname> and <varname>After=</varname> dependencies on the specified + slice unit.</para></listitem> + </itemizedlist> + </refsect1> + + <!-- We don't have any default dependency here. --> + + <refsect1> + <title>Options</title> + + <para>Units of the types listed above can have settings for resource control configuration:</para> + + <refsect2><title>CPU Accounting and Control</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>CPUAccounting=</varname></term> + + <listitem> + <para>Turn on CPU usage accounting for this unit. Takes a + boolean argument. Note that turning on CPU accounting for + one unit will also implicitly turn it on for all units + contained in the same slice and for all its parent slices + and the units contained therein. The system default for this + setting may be controlled with + <varname>DefaultCPUAccounting=</varname> in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <para>Under the unified cgroup hierarchy, CPU accounting is available for all units and this + setting has no effect.</para> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>CPUWeight=<replaceable>weight</replaceable></varname></term> + <term><varname>StartupCPUWeight=<replaceable>weight</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>cpu</option> controller in the unified hierarchy.</para> + + <para>These options accept an integer value or a the special string "idle":</para> + <itemizedlist> + <listitem> + <para>If set to an integer value, assign the specified CPU time weight to the processes + executed, if the unified control group hierarchy is used on the system. These options control + the <literal>cpu.weight</literal> control group attribute. The allowed range is 1 to 10000. + Defaults to unset, but the kernel default is 100. For details about this control group + attribute, see <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html">Control Groups + v2</ulink> and <ulink url="https://docs.kernel.org/scheduler/sched-design-CFS.html">CFS + Scheduler</ulink>. The available CPU time is split up among all units within one slice + relative to their CPU time weight. A higher weight means more CPU time, a lower weight means + less.</para> + </listitem> + <listitem> + <para>If set to the special string "idle", mark the cgroup for "idle scheduling", which means + that it will get CPU resources only when there are no processes not marked in this way to execute in this + cgroup or its siblings. This setting corresponds to the <literal>cpu.idle</literal> cgroup attribute.</para> + + <para>Note that this value only has an effect on cgroup-v2, for cgroup-v1 it is equivalent to the minimum weight.</para> + </listitem> + </itemizedlist> + + <para>While <varname>StartupCPUWeight=</varname> applies to the startup and shutdown phases of the system, + <varname>CPUWeight=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupCPUWeight=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <para>In addition to the resource allocation performed by the <option>cpu</option> controller, the + kernel may automatically divide resources based on session-id grouping, see "The autogroup feature" + in <citerefentry + project='man-pages'><refentrytitle>sched</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + The effect of this feature is similar to the <option>cpu</option> controller with no explicit + configuration, so users should be careful to not mistake one for the other.</para> + + <xi:include href="version-info.xml" xpointer="v232"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>CPUQuota=</varname></term> + + <listitem> + <para>This setting controls the <option>cpu</option> controller in the unified hierarchy.</para> + + <para>Assign the specified CPU time quota to the processes executed. Takes a percentage value, suffixed with + "%". The percentage specifies how much CPU time the unit shall get at maximum, relative to the total CPU time + available on one CPU. Use values > 100% for allotting CPU time on more than one CPU. This controls the + <literal>cpu.max</literal> attribute on the unified control group hierarchy and + <literal>cpu.cfs_quota_us</literal> on legacy. For details about these control group attributes, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html">Control Groups v2</ulink> and <ulink + url="https://docs.kernel.org/scheduler/sched-bwc.html">CFS Bandwidth Control</ulink>. + Setting <varname>CPUQuota=</varname> to an empty value unsets the quota.</para> + + <para>Example: <varname>CPUQuota=20%</varname> ensures that the executed processes will never get more than + 20% CPU time on one CPU.</para> + + <xi:include href="version-info.xml" xpointer="v213"/> + + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>CPUQuotaPeriodSec=</varname></term> + + <listitem> + <para>This setting controls the <option>cpu</option> controller in the unified hierarchy.</para> + + <para>Assign the duration over which the CPU time quota specified by <varname>CPUQuota=</varname> is measured. + Takes a time duration value in seconds, with an optional suffix such as "ms" for milliseconds (or "s" for seconds.) + The default setting is 100ms. The period is clamped to the range supported by the kernel, which is [1ms, 1000ms]. + Additionally, the period is adjusted up so that the quota interval is also at least 1ms. + Setting <varname>CPUQuotaPeriodSec=</varname> to an empty value resets it to the default.</para> + + <para>This controls the second field of <literal>cpu.max</literal> attribute on the unified control group hierarchy + and <literal>cpu.cfs_period_us</literal> on legacy. For details about these control group attributes, see + <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html">Control Groups v2</ulink> and + <ulink url="https://docs.kernel.org/scheduler/sched-design-CFS.html">CFS Scheduler</ulink>.</para> + + <para>Example: <varname>CPUQuotaPeriodSec=10ms</varname> to request that the CPU quota is measured in periods of 10ms.</para> + + <xi:include href="version-info.xml" xpointer="v242"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>AllowedCPUs=</varname></term> + <term><varname>StartupAllowedCPUs=</varname></term> + + <listitem> + <para>This setting controls the <option>cpuset</option> controller in the unified hierarchy.</para> + + <para>Restrict processes to be executed on specific CPUs. Takes a list of CPU indices or ranges separated by either + whitespace or commas. CPU ranges are specified by the lower and upper CPU indices separated by a dash.</para> + + <para>Setting <varname>AllowedCPUs=</varname> or <varname>StartupAllowedCPUs=</varname> doesn't guarantee that all + of the CPUs will be used by the processes as it may be limited by parent units. The effective configuration is + reported as <varname>EffectiveCPUs=</varname>.</para> + + <para>While <varname>StartupAllowedCPUs=</varname> applies to the startup and shutdown phases of the system, + <varname>AllowedCPUs=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupAllowedCPUs=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <para>This setting is supported only with the unified control group hierarchy.</para> + + <xi:include href="version-info.xml" xpointer="v244"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>Memory Accounting and Control</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>MemoryAccounting=</varname></term> + + <listitem> + <para>This setting controls the <option>memory</option> controller in the unified hierarchy.</para> + + <para>Turn on process and kernel memory accounting for this + unit. Takes a boolean argument. Note that turning on memory + accounting for one unit will also implicitly turn it on for + all units contained in the same slice and for all its parent + slices and the units contained therein. The system default + for this setting may be controlled with + <varname>DefaultMemoryAccounting=</varname> in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemoryMin=<replaceable>bytes</replaceable></varname>, <varname>MemoryLow=<replaceable>bytes</replaceable></varname></term> + <term><varname>StartupMemoryLow=<replaceable>bytes</replaceable></varname>, <varname>DefaultStartupMemoryLow=<replaceable>bytes</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>memory</option> controller in the unified hierarchy.</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.min</literal> or <literal>memory.low</literal> control group attribute. + For details about this control group attribute, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</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>, or <varname>DefaultStartupMemoryLow=</varname> + which has the same semantics as <varname>StartupMemoryLow=</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> + + <para>While <varname>StartupMemoryLow=</varname> applies to the startup and shutdown phases of the system, + <varname>MemoryMin=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupMemoryLow=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <xi:include href="version-info.xml" xpointer="v240"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemoryHigh=<replaceable>bytes</replaceable></varname></term> + <term><varname>StartupMemoryHigh=<replaceable>bytes</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>memory</option> controller in the unified hierarchy.</para> + + <para>Specify the throttling limit on memory usage of the executed processes in this unit. Memory usage may go + above the limit if unavoidable, but the processes are heavily slowed down and memory is taken away + aggressively in such cases. This is the main mechanism to control memory usage of a unit.</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>, no memory throttling is applied. This controls the + <literal>memory.high</literal> control group attribute. For details about this control group attribute, see + <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para> + + <para>While <varname>StartupMemoryHigh=</varname> applies to the startup and shutdown phases of the system, + <varname>MemoryHigh=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupMemoryHigh=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <xi:include href="version-info.xml" xpointer="v231"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemoryMax=<replaceable>bytes</replaceable></varname></term> + <term><varname>StartupMemoryMax=<replaceable>bytes</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>memory</option> controller in the unified hierarchy.</para> + + <para>Specify the absolute limit on memory usage of the executed processes in this unit. If memory usage + cannot be contained under the limit, out-of-memory killer is invoked inside the unit. It is recommended to + use <varname>MemoryHigh=</varname> as the main control mechanism and use <varname>MemoryMax=</varname> as the + last line of defense.</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>, no memory limit is applied. This controls the + <literal>memory.max</literal> control group attribute. For details about this control group attribute, see + <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para> + + <para>While <varname>StartupMemoryMax=</varname> applies to the startup and shutdown phases of the system, + <varname>MemoryMax=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupMemoryMax=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <xi:include href="version-info.xml" xpointer="v231"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemorySwapMax=<replaceable>bytes</replaceable></varname></term> + <term><varname>StartupMemorySwapMax=<replaceable>bytes</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>memory</option> controller in the unified hierarchy.</para> + + <para>Specify the absolute limit on swap usage of the executed processes in this unit.</para> + + <para>Takes a swap size in bytes. If the value is suffixed with K, M, G or T, the specified swap size is + parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. If assigned the + special value <literal>infinity</literal>, no swap limit is applied. These settings control the + <literal>memory.swap.max</literal> control group attribute. For details about this control group attribute, + see <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para> + + <para>While <varname>StartupMemorySwapMax=</varname> applies to the startup and shutdown phases of the system, + <varname>MemorySwapMax=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupMemorySwapMax=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <xi:include href="version-info.xml" xpointer="v232"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemoryZSwapMax=<replaceable>bytes</replaceable></varname></term> + <term><varname>StartupMemoryZSwapMax=<replaceable>bytes</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>memory</option> controller in the unified hierarchy.</para> + + <para>Specify the absolute limit on zswap usage of the processes in this unit. Zswap is a lightweight compressed + cache for swap pages. It takes pages that are in the process of being swapped out and attempts to compress them into a + dynamically allocated RAM-based memory pool. If the limit specified is hit, no entries from this unit will be + stored in the pool until existing entries are faulted back or written out to disk. See the kernel's + <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/mm/zswap.html">Zswap</ulink> documentation for more details.</para> + + <para>Takes a size in bytes. If the value is suffixed with K, M, G or T, the specified size is + parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. If assigned the + special value <literal>infinity</literal>, no limit is applied. These settings control the + <literal>memory.zswap.max</literal> control group attribute. For details about this control group attribute, + see <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para> + + <para>While <varname>StartupMemoryZSwapMax=</varname> applies to the startup and shutdown phases of the system, + <varname>MemoryZSwapMax=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupMemoryZSwapMax=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <xi:include href="version-info.xml" xpointer="v253"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>AllowedMemoryNodes=</varname></term> + <term><varname>StartupAllowedMemoryNodes=</varname></term> + + <listitem> + <para>These settings control the <option>cpuset</option> controller in the unified hierarchy.</para> + + <para>Restrict processes to be executed on specific memory NUMA nodes. Takes a list of memory NUMA nodes indices + or ranges separated by either whitespace or commas. Memory NUMA nodes ranges are specified by the lower and upper + NUMA nodes indices separated by a dash.</para> + + <para>Setting <varname>AllowedMemoryNodes=</varname> or <varname>StartupAllowedMemoryNodes=</varname> doesn't + guarantee that all of the memory NUMA nodes will be used by the processes as it may be limited by parent units. + The effective configuration is reported as <varname>EffectiveMemoryNodes=</varname>.</para> + + <para>While <varname>StartupAllowedMemoryNodes=</varname> applies to the startup and shutdown phases of the system, + <varname>AllowedMemoryNodes=</varname> applies to normal runtime of the system, and if the former is not set also to + the startup and shutdown phases. Using <varname>StartupAllowedMemoryNodes=</varname> allows prioritizing specific services at + boot-up and shutdown differently than during normal runtime.</para> + + <para>This setting is supported only with the unified control group hierarchy.</para> + + <xi:include href="version-info.xml" xpointer="v244"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>Process Accounting and Control</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>TasksAccounting=</varname></term> + + <listitem> + <para>This setting controls the <option>pids</option> controller in the unified hierarchy.</para> + + <para>Turn on task accounting for this unit. Takes a boolean argument. If enabled, the kernel will + keep track of the total number of tasks in the unit and its children. This number includes both + kernel threads and userspace processes, with each thread counted individually. Note that turning on + tasks accounting for one unit will also implicitly turn it on for all units contained in the same + slice and for all its parent slices and the units contained therein. The system default for this + setting may be controlled with <varname>DefaultTasksAccounting=</varname> in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v227"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>TasksMax=<replaceable>N</replaceable></varname></term> + + <listitem> + <para>This setting controls the <option>pids</option> controller in the unified hierarchy.</para> + + <para>Specify the maximum number of tasks that may be created in the unit. This ensures that the + number of tasks accounted for the unit (see above) stays below a specific limit. This either takes + an absolute number of tasks or a percentage value that is taken relative to the configured maximum + number of tasks on the system. If assigned the special value <literal>infinity</literal>, no tasks + limit is applied. This controls the <literal>pids.max</literal> control group attribute. For + details about this control group attribute, the + <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#pid">pids controller + </ulink>.</para> + + <para>The system default for this setting may be controlled with + <varname>DefaultTasksMax=</varname> in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v227"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>IO Accounting and Control</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>IOAccounting=</varname></term> + + <listitem> + <para>This setting controls the <option>io</option> controller in the unified hierarchy.</para> + + <para>Turn on Block I/O accounting for this unit, if the unified control group hierarchy is used on the + system. Takes a boolean argument. Note that turning on block I/O accounting for one unit will also implicitly + turn it on for all units contained in the same slice and all for its parent slices and the units contained + therein. The system default for this setting may be controlled with <varname>DefaultIOAccounting=</varname> + in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v230"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IOWeight=<replaceable>weight</replaceable></varname></term> + <term><varname>StartupIOWeight=<replaceable>weight</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>io</option> controller in the unified hierarchy.</para> + + <para>Set the default overall block I/O weight for the executed processes, if the unified control + group hierarchy is used on the system. Takes a single weight value (between 1 and 10000) to set the + default block I/O weight. This controls the <literal>io.weight</literal> control group attribute, + which defaults to 100. For details about this control group attribute, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html#io-interface-files">IO + Interface Files</ulink>. The available I/O bandwidth is split up among all units within one slice + relative to their block I/O weight. A higher weight means more I/O bandwidth, a lower weight means + less.</para> + + <para>While <varname>StartupIOWeight=</varname> applies + to the startup and shutdown phases of the system, + <varname>IOWeight=</varname> applies to the later runtime of + the system, and if the former is not set also to the startup + and shutdown phases. This allows prioritizing specific services at boot-up + and shutdown differently than during runtime.</para> + + <xi:include href="version-info.xml" xpointer="v230"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term> + + <listitem> + <para>This setting controls the <option>io</option> controller in the unified hierarchy.</para> + + <para>Set the per-device overall block I/O weight for the executed processes, if the unified control group + hierarchy is used on the system. Takes a space-separated pair of a file path and a weight value to specify + the device specific weight value, between 1 and 10000. (Example: <literal>/dev/sda 1000</literal>). The file + path may be specified as path to a block device node or as any other file, in which case the backing block + device of the file system of the file is determined. This controls the <literal>io.weight</literal> control + group attribute, which defaults to 100. Use this option multiple times to set weights for multiple devices. + For details about this control group attribute, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html#io-interface-files">IO Interface Files</ulink>.</para> + + <para>The specified device node should reference a block device that has an I/O scheduler + associated, i.e. should not refer to partition or loopback block devices, but to the originating, + physical device. When a path to a regular file or directory is specified it is attempted to + discover the correct originating device backing the file system of the specified path. This works + correctly only for simpler cases, where the file system is directly placed on a partition or + physical block device, or where simple 1:1 encryption using dm-crypt/LUKS is used. This discovery + does not cover complex storage and in particular RAID and volume management storage devices.</para> + + <xi:include href="version-info.xml" xpointer="v230"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IOReadBandwidthMax=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term> + <term><varname>IOWriteBandwidthMax=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>io</option> controller in the unified hierarchy.</para> + + <para>Set the per-device overall block I/O bandwidth maximum limit for the executed processes, if the unified + control group hierarchy is used on the system. This limit is not work-conserving and the executed processes + are not allowed to use more even if the device has idle capacity. Takes a space-separated pair of a file + path and a bandwidth value (in bytes per second) to specify the device specific bandwidth. The file path may + be a path to a block device node, or as any other file in which case the backing block device of the file + system of the file is used. If the bandwidth is suffixed with K, M, G, or T, the specified bandwidth is + parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes, respectively, to the base of 1000. (Example: + "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This controls the <literal>io.max</literal> control + group attributes. Use this option multiple times to set bandwidth limits for multiple devices. For details + about this control group attribute, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html#io-interface-files">IO Interface Files</ulink>. + </para> + + <para>Similar restrictions on block device discovery as for <varname>IODeviceWeight=</varname> apply, see above.</para> + + <xi:include href="version-info.xml" xpointer="v230"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IOReadIOPSMax=<replaceable>device</replaceable> <replaceable>IOPS</replaceable></varname></term> + <term><varname>IOWriteIOPSMax=<replaceable>device</replaceable> <replaceable>IOPS</replaceable></varname></term> + + <listitem> + <para>These settings control the <option>io</option> controller in the unified hierarchy.</para> + + <para>Set the per-device overall block I/O IOs-Per-Second maximum limit for the executed processes, if the + unified control group hierarchy is used on the system. This limit is not work-conserving and the executed + processes are not allowed to use more even if the device has idle capacity. Takes a space-separated pair of + a file path and an IOPS value to specify the device specific IOPS. The file path may be a path to a block + device node, or as any other file in which case the backing block device of the file system of the file is + used. If the IOPS is suffixed with K, M, G, or T, the specified IOPS is parsed as KiloIOPS, MegaIOPS, + GigaIOPS, or TeraIOPS, respectively, to the base of 1000. (Example: + "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 1K"). This controls the <literal>io.max</literal> control + group attributes. Use this option multiple times to set IOPS limits for multiple devices. For details about + this control group attribute, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html#io-interface-files">IO Interface Files</ulink>. + </para> + + <para>Similar restrictions on block device discovery as for <varname>IODeviceWeight=</varname> apply, see above.</para> + + <xi:include href="version-info.xml" xpointer="v230"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IODeviceLatencyTargetSec=<replaceable>device</replaceable> <replaceable>target</replaceable></varname></term> + + <listitem> + <para>This setting controls the <option>io</option> controller in the unified hierarchy.</para> + + <para>Set the per-device average target I/O latency for the executed processes, if the unified control group + hierarchy is used on the system. Takes a file path and a timespan separated by a space to specify + the device specific latency target. (Example: "/dev/sda 25ms"). The file path may be specified + as path to a block device node or as any other file, in which case the backing block device of the file + system of the file is determined. This controls the <literal>io.latency</literal> control group + attribute. Use this option multiple times to set latency target for multiple devices. For details about this + control group attribute, see <ulink + url="https://docs.kernel.org/admin-guide/cgroup-v2.html#io-interface-files">IO Interface Files</ulink>.</para> + + <para>Implies <literal>IOAccounting=yes</literal>.</para> + + <para>These settings are supported only if the unified control group hierarchy is used.</para> + + <para>Similar restrictions on block device discovery as for <varname>IODeviceWeight=</varname> apply, see above.</para> + + <xi:include href="version-info.xml" xpointer="v240"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>Network Accounting and Control</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>IPAccounting=</varname></term> + + <listitem> + <para>Takes a boolean argument. If true, turns on IPv4 and IPv6 network traffic accounting for packets sent + or received by the unit. When this option is turned on, all IPv4 and IPv6 sockets created by any process of + the unit are accounted for.</para> + + <para>When this option is used in socket units, it applies to all IPv4 and IPv6 sockets + associated with it (including both listening and connection sockets where this applies). Note that for + socket-activated services, this configuration setting and the accounting data of the service unit and the + socket unit are kept separate, and displayed separately. No propagation of the setting and the collected + statistics is done, in either direction. Moreover, any traffic sent or received on any of the socket unit's + sockets is accounted to the socket unit — and never to the service unit it might have activated, even if the + socket is used by it.</para> + + <para>The system default for this setting may be controlled with <varname>DefaultIPAccounting=</varname> in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v235"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IPAddressAllow=<replaceable>ADDRESS[/PREFIXLENGTH]…</replaceable></varname></term> + <term><varname>IPAddressDeny=<replaceable>ADDRESS[/PREFIXLENGTH]…</replaceable></varname></term> + + <listitem> + <para>Turn on network traffic filtering for IP packets sent and received over + <constant>AF_INET</constant> and <constant>AF_INET6</constant> sockets. Both directives take a + space separated list of IPv4 or IPv6 addresses, each optionally suffixed with an address prefix + length in bits after a <literal>/</literal> character. If the suffix is omitted, the address is + considered a host address, i.e. the filter covers the whole address (32 bits for IPv4, 128 bits for + IPv6).</para> + + <para>The access lists configured with this option are applied to all sockets created by processes + of this unit (or in the case of socket units, associated with it). The lists are implicitly + combined with any lists configured for any of the parent slice units this unit might be a member + of. By default both access lists are empty. Both ingress and egress traffic is filtered by these + settings. In case of ingress traffic the source IP address is checked against these access lists, + in case of egress traffic the destination IP address is checked. The following rules are applied in + turn:</para> + + <itemizedlist> + <listitem><para>Access is granted when the checked IP address matches an entry in the + <varname>IPAddressAllow=</varname> list.</para></listitem> + + <listitem><para>Otherwise, access is denied when the checked IP address matches an entry in the + <varname>IPAddressDeny=</varname> list.</para></listitem> + + <listitem><para>Otherwise, access is granted.</para></listitem> + </itemizedlist> + + <para>In order to implement an allow-listing IP firewall, it is recommended to use a + <varname>IPAddressDeny=</varname><constant>any</constant> setting on an upper-level slice unit + (such as the root slice <filename>-.slice</filename> or the slice containing all system services + <filename>system.slice</filename> – see + <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> + for details on these slice units), plus individual per-service <varname>IPAddressAllow=</varname> + lines permitting network access to relevant services, and only them.</para> + + <para>Note that for socket-activated services, the IP access list configured on the socket unit + applies to all sockets associated with it directly, but not to any sockets created by the + ultimately activated services for it. Conversely, the IP access list configured for the service is + not applied to any sockets passed into the service via socket activation. Thus, it is usually a + good idea to replicate the IP access lists on both the socket and the service unit. Nevertheless, + it may make sense to maintain one list more open and the other one more restricted, depending on + the use case.</para> + + <para>If these settings are used multiple times in the same unit the specified lists are combined. If an + empty string is assigned to these settings the specific access list is reset and all previous settings undone.</para> + + <para>In place of explicit IPv4 or IPv6 address and prefix length specifications a small set of symbolic + names may be used. The following names are defined:</para> + + <table> + <title>Special address/network names</title> + + <tgroup cols='3'> + <colspec colname='name'/> + <colspec colname='definition'/> + <colspec colname='meaning'/> + + <thead> + <row> + <entry>Symbolic Name</entry> + <entry>Definition</entry> + <entry>Meaning</entry> + </row> + </thead> + + <tbody> + <row> + <entry><constant>any</constant></entry> + <entry>0.0.0.0/0 ::/0</entry> + <entry>Any host</entry> + </row> + + <row> + <entry><constant>localhost</constant></entry> + <entry>127.0.0.0/8 ::1/128</entry> + <entry>All addresses on the local loopback</entry> + </row> + + <row> + <entry><constant>link-local</constant></entry> + <entry>169.254.0.0/16 fe80::/64</entry> + <entry>All link-local IP addresses</entry> + </row> + + <row> + <entry><constant>multicast</constant></entry> + <entry>224.0.0.0/4 ff00::/8</entry> + <entry>All IP multicasting addresses</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Note that these settings might not be supported on some systems (for example if eBPF control group + support is not enabled in the underlying kernel or container manager). These settings will have no effect in + that case. If compatibility with such systems is desired it is hence recommended to not exclusively rely on + them for IP security.</para> + + <xi:include href="cgroup-sandboxing.xml" xpointer="singular"/> + + <xi:include href="version-info.xml" xpointer="v235"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>SocketBindAllow=<replaceable>bind-rule</replaceable></varname></term> + <term><varname>SocketBindDeny=<replaceable>bind-rule</replaceable></varname></term> + + <listitem> + <para>Allow or deny binding a socket address to a socket by matching it with the <replaceable>bind-rule</replaceable> and + applying a corresponding action if there is a match.</para> + + <para><replaceable>bind-rule</replaceable> describes socket properties such as <replaceable>address-family</replaceable>, + <replaceable>transport-protocol</replaceable> and <replaceable>ip-ports</replaceable>.</para> + + <para><replaceable>bind-rule</replaceable> := + { [<replaceable>address-family</replaceable><constant>:</constant>][<replaceable>transport-protocol</replaceable><constant>:</constant>][<replaceable>ip-ports</replaceable>] | <constant>any</constant> }</para> + + <para><replaceable>address-family</replaceable> := { <constant>ipv4</constant> | <constant>ipv6</constant> }</para> + + <para><replaceable>transport-protocol</replaceable> := { <constant>tcp</constant> | <constant>udp</constant> }</para> + + <para><replaceable>ip-ports</replaceable> := { <replaceable>ip-port</replaceable> | <replaceable>ip-port-range</replaceable> }</para> + + <para>An optional <replaceable>address-family</replaceable> expects <constant>ipv4</constant> or <constant>ipv6</constant> values. + If not specified, a rule will be matched for both IPv4 and IPv6 addresses and applied depending on other socket fields, e.g. <replaceable>transport-protocol</replaceable>, + <replaceable>ip-port</replaceable>.</para> + + <para>An optional <replaceable>transport-protocol</replaceable> expects <constant>tcp</constant> or <constant>udp</constant> transport protocol names. + If not specified, a rule will be matched for any transport protocol.</para> + + <para>An optional <replaceable>ip-port</replaceable> value must lie within 1…65535 interval inclusively, i.e. + dynamic port <constant>0</constant> is not allowed. A range of sequential ports is described by + <replaceable>ip-port-range</replaceable> := <replaceable>ip-port-low</replaceable><constant>-</constant><replaceable>ip-port-high</replaceable>, + where <replaceable>ip-port-low</replaceable> is smaller than or equal to <replaceable>ip-port-high</replaceable> + and both are within 1…65535 inclusively.</para> + + <para>A special value <constant>any</constant> can be used to apply a rule to any address family, transport protocol and any port with a positive value.</para> + + <para>To allow multiple rules assign <varname>SocketBindAllow=</varname> or <varname>SocketBindDeny=</varname> multiple times. + To clear the existing assignments pass an empty <varname>SocketBindAllow=</varname> or <varname>SocketBindDeny=</varname> + assignment.</para> + + <para>For each of <varname>SocketBindAllow=</varname> and <varname>SocketBindDeny=</varname>, maximum allowed number of assignments is + <constant>128</constant>.</para> + + <itemizedlist> + <listitem><para>Binding to a socket is allowed when a socket address matches an entry in the + <varname>SocketBindAllow=</varname> list.</para></listitem> + + <listitem><para>Otherwise, binding is denied when the socket address matches an entry in the + <varname>SocketBindDeny=</varname> list.</para></listitem> + + <listitem><para>Otherwise, binding is allowed.</para></listitem> + </itemizedlist> + + <para>The feature is implemented with <constant>cgroup/bind4</constant> and <constant>cgroup/bind6</constant> cgroup-bpf hooks.</para> + <para>Examples:<programlisting>… +# Allow binding IPv6 socket addresses with a port greater than or equal to 10000. +[Service] +SocketBindAllow=ipv6:10000-65535 +SocketBindDeny=any +… +# Allow binding IPv4 and IPv6 socket addresses with 1234 and 4321 ports. +[Service] +SocketBindAllow=1234 +SocketBindAllow=4321 +SocketBindDeny=any +… +# Deny binding IPv6 socket addresses. +[Service] +SocketBindDeny=ipv6 +… +# Deny binding IPv4 and IPv6 socket addresses. +[Service] +SocketBindDeny=any +… +# Allow binding only over TCP +[Service] +SocketBindAllow=tcp +SocketBindDeny=any +… +# Allow binding only over IPv6/TCP +[Service] +SocketBindAllow=ipv6:tcp +SocketBindDeny=any +… +# Allow binding ports within 10000-65535 range over IPv4/UDP. +[Service] +SocketBindAllow=ipv4:udp:10000-65535 +SocketBindDeny=any +…</programlisting></para> + + <xi:include href="cgroup-sandboxing.xml" xpointer="singular"/> + + <xi:include href="version-info.xml" xpointer="v249"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>RestrictNetworkInterfaces=</varname></term> + + <listitem> + <para>Takes a list of space-separated network interface names. This option restricts the network + interfaces that processes of this unit can use. By default processes can only use the network interfaces + listed (allow-list). If the first character of the rule is <literal>~</literal>, the effect is inverted: + the processes can only use network interfaces not listed (deny-list). + </para> + + <para>This option can appear multiple times, in which case the network interface names are merged. If the + empty string is assigned the set is reset, all prior assignments will have not effect. + </para> + + <para>If you specify both types of this option (i.e. allow-listing and deny-listing), the first encountered + will take precedence and will dictate the default action (allow vs deny). Then the next occurrences of this + option will add or delete the listed network interface names from the set, depending of its type and the + default action. + </para> + + <para>The loopback interface ("lo") is not treated in any special way, you have to configure it explicitly + in the unit file. + </para> + <para>Example 1: allow-list + <programlisting> +RestrictNetworkInterfaces=eth1 +RestrictNetworkInterfaces=eth2</programlisting> + Programs in the unit will be only able to use the eth1 and eth2 network + interfaces. + </para> + + <para>Example 2: deny-list + <programlisting> +RestrictNetworkInterfaces=~eth1 eth2</programlisting> + Programs in the unit will be able to use any network interface but eth1 and eth2. + </para> + + <para>Example 3: mixed + <programlisting> +RestrictNetworkInterfaces=eth1 eth2 +RestrictNetworkInterfaces=~eth1</programlisting> + Programs in the unit will be only able to use the eth2 network interface. + </para> + + <xi:include href="cgroup-sandboxing.xml" xpointer="singular"/> + + <xi:include href="version-info.xml" xpointer="v250"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>NFTSet=</varname><replaceable>family</replaceable>:<replaceable>table</replaceable>:<replaceable>set</replaceable></term> + <listitem> + <para>This setting provides a method for integrating dynamic cgroup, user and group IDs into + firewall rules with <ulink url="https://netfilter.org/projects/nftables/index.html">NFT</ulink> + sets. The benefit of using this setting is to be able to use the IDs as selectors in firewall rules + easily and this in turn allows more fine grained filtering. NFT rules for cgroup matching use + numeric cgroup IDs, which change every time a service is restarted, making them hard to use in + systemd environment otherwise. Dynamic and random IDs used by <varname>DynamicUser=</varname> can + be also integrated with this setting.</para> + + <para>This option expects a whitespace separated list of NFT set definitions. Each definition + consists of a colon-separated tuple of source type (one of <literal>cgroup</literal>, + <literal>user</literal> or <literal>group</literal>), NFT address family (one of + <literal>arp</literal>, <literal>bridge</literal>, <literal>inet</literal>, <literal>ip</literal>, + <literal>ip6</literal>, or <literal>netdev</literal>), table name and set name. The names of tables + and sets must conform to lexical restrictions of NFT table names. The type of the element used in + the NFT filter must match the type implied by the directive (<literal>cgroup</literal>, + <literal>user</literal> or <literal>group</literal>) as shown in the table below. When a control + group or a unit is realized, the corresponding ID will be appended to the NFT sets and it will be + be removed when the control group or unit is removed. <command>systemd</command> only inserts + elements to (or removes from) the sets, so the related NFT rules, tables and sets must be prepared + elsewhere in advance. Failures to manage the sets will be ignored.</para> + + <table> + <title>Defined <varname>source type</varname> values</title> + <tgroup cols='3'> + <colspec colname='source type'/> + <colspec colname='description'/> + <colspec colname='NFT type name'/> + <thead> + <row> + <entry>Source type</entry> + <entry>Description</entry> + <entry>Corresponding NFT type name</entry> + </row> + </thead> + + <tbody> + <row> + <entry><literal>cgroup</literal></entry> + <entry>control group ID</entry> + <entry><literal>cgroupsv2</literal></entry> + </row> + <row> + <entry><literal>user</literal></entry> + <entry>user ID</entry> + <entry><literal>meta skuid</literal></entry> + </row> + <row> + <entry><literal>group</literal></entry> + <entry>group ID</entry> + <entry><literal>meta skgid</literal></entry> + </row> + </tbody> + </tgroup> + </table> + + <para>If the firewall rules are reinstalled so that the contents of NFT sets are destroyed, command + <command>systemctl daemon-reload</command> can be used to refill the sets.</para> + + <para>Example: + <programlisting>[Unit] +NFTSet=cgroup:inet:filter:my_service user:inet:filter:serviceuser +</programlisting> + Corresponding NFT rules: + <programlisting>table inet filter { + set my_service { + type cgroupsv2 + } + set serviceuser { + typeof meta skuid + } + chain x { + socket cgroupv2 level 2 @my_service accept + drop + } + chain y { + meta skuid @serviceuser accept + drop + } +}</programlisting> + </para> + <xi:include href="version-info.xml" xpointer="v255"/></listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>BPF Programs</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>IPIngressFilterPath=<replaceable>BPF_FS_PROGRAM_PATH</replaceable></varname></term> + <term><varname>IPEgressFilterPath=<replaceable>BPF_FS_PROGRAM_PATH</replaceable></varname></term> + + <listitem> + <para>Add custom network traffic filters implemented as BPF programs, applying to all IP packets + sent and received over <constant>AF_INET</constant> and <constant>AF_INET6</constant> sockets. + Takes an absolute path to a pinned BPF program in the BPF virtual filesystem (<filename>/sys/fs/bpf/</filename>). + </para> + + <para>The filters configured with this option are applied to all sockets created by processes + of this unit (or in the case of socket units, associated with it). The filters are loaded in addition + to filters any of the parent slice units this unit might be a member of as well as any + <varname>IPAddressAllow=</varname> and <varname>IPAddressDeny=</varname> filters in any of these units. + By default there are no filters specified.</para> + + <para>If these settings are used multiple times in the same unit all the specified programs are attached. If an + empty string is assigned to these settings the program list is reset and all previous specified programs ignored.</para> + + <para>If the path <replaceable>BPF_FS_PROGRAM_PATH</replaceable> in <varname>IPIngressFilterPath=</varname> assignment + is already being handled by <varname>BPFProgram=</varname> ingress hook, e.g. + <varname>BPFProgram=</varname><constant>ingress</constant>:<replaceable>BPF_FS_PROGRAM_PATH</replaceable>, + the assignment will be still considered valid and the program will be attached to a cgroup. Same for + <varname>IPEgressFilterPath=</varname> path and <constant>egress</constant> hook.</para> + + <para>Note that for socket-activated services, the IP filter programs configured on the socket unit apply to + all sockets associated with it directly, but not to any sockets created by the ultimately activated services + for it. Conversely, the IP filter programs configured for the service are not applied to any sockets passed into + the service via socket activation. Thus, it is usually a good idea, to replicate the IP filter programs on both + the socket and the service unit, however it often makes sense to maintain one configuration more open and the other + one more restricted, depending on the use case.</para> + + <para>Note that these settings might not be supported on some systems (for example if eBPF control group + support is not enabled in the underlying kernel or container manager). These settings will fail the service in + that case. If compatibility with such systems is desired it is hence recommended to attach your filter manually + (requires <varname>Delegate=</varname><constant>yes</constant>) instead of using this setting.</para> + + <xi:include href="version-info.xml" xpointer="v243"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>BPFProgram=<replaceable>type</replaceable>:<replaceable>program-path</replaceable></varname></term> + <listitem> + <para><varname>BPFProgram=</varname> allows attaching custom BPF programs to the cgroup of a + unit. (This generalizes the functionality exposed via <varname>IPEgressFilterPath=</varname> and + <varname>IPIngressFilterPath=</varname> for other hooks.) Cgroup-bpf hooks in the form of BPF + programs loaded to the BPF filesystem are attached with cgroup-bpf attach flags determined by the + unit. For details about attachment types and flags see <ulink + url="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/include/uapi/linux/bpf.h"><filename>bpf.h</filename></ulink>. Also + refer to the general <ulink url="https://docs.kernel.org/bpf/">BPF documentation</ulink>.</para> + + <para>The specification of BPF program consists of a pair of BPF program type and program path in + the file system, with <literal>:</literal> as the separator: + <replaceable>type</replaceable>:<replaceable>program-path</replaceable>.</para> + + <para>The BPF program type is equivalent to the BPF attach type used in + <citerefentry project='mankier'><refentrytitle>bpftool</refentrytitle><manvolnum>8</manvolnum></citerefentry> + It may be one of + <constant>egress</constant>, + <constant>ingress</constant>, + <constant>sock_create</constant>, + <constant>sock_ops</constant>, + <constant>device</constant>, + <constant>bind4</constant>, + <constant>bind6</constant>, + <constant>connect4</constant>, + <constant>connect6</constant>, + <constant>post_bind4</constant>, + <constant>post_bind6</constant>, + <constant>sendmsg4</constant>, + <constant>sendmsg6</constant>, + <constant>sysctl</constant>, + <constant>recvmsg4</constant>, + <constant>recvmsg6</constant>, + <constant>getsockopt</constant>, + or <constant>setsockopt</constant>. + </para> + + <para>The specified program path must be an absolute path referencing a BPF program inode in the + bpffs file system (which generally means it must begin with <filename>/sys/fs/bpf/</filename>). If + a specified program does not exist (i.e. has not been uploaded to the BPF subsystem of the kernel + yet), it will not be installed but unit activation will continue (a warning will be printed to the + logs).</para> + + <para>Setting <varname>BPFProgram=</varname> to an empty value makes previous assignments + ineffective.</para> + + <para>Multiple assignments of the same program type/path pair have the same effect as a single + assignment: the program will be attached just once.</para> + + <para>If BPF <constant>egress</constant> pinned to <replaceable>program-path</replaceable> path is already being + handled by <varname>IPEgressFilterPath=</varname>, <varname>BPFProgram=</varname> + assignment will be considered valid and <varname>BPFProgram=</varname> will be attached to a cgroup. + Similarly for <constant>ingress</constant> hook and <varname>IPIngressFilterPath=</varname> assignment.</para> + + <para>BPF programs passed with <varname>BPFProgram=</varname> are attached to the cgroup of a unit + with BPF attach flag <constant>multi</constant>, that allows further attachments of the same + <replaceable>type</replaceable> within cgroup hierarchy topped by the unit cgroup.</para> + + <para>Examples:<programlisting>BPFProgram=egress:/sys/fs/bpf/egress-hook +BPFProgram=bind6:/sys/fs/bpf/sock-addr-hook +</programlisting></para> + + <xi:include href="version-info.xml" xpointer="v249"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>Device Access</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>DeviceAllow=</varname></term> + + <listitem> + <para>Control access to specific device nodes by the executed processes. Takes two space-separated + strings: a device node specifier followed by a combination of <constant>r</constant>, + <constant>w</constant>, <constant>m</constant> to control <emphasis>r</emphasis>eading, + <emphasis>w</emphasis>riting, or creation of the specific device nodes by the unit + (<emphasis>m</emphasis>knod), respectively. This functionality is implemented using eBPF + filtering.</para> + + <para>When access to <emphasis>all</emphasis> physical devices should be disallowed, + <varname>PrivateDevices=</varname> may be used instead. See + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + </para> + + <para>The device node specifier is either a path to a device node in the file system, starting with + <filename>/dev/</filename>, or a string starting with either <literal>char-</literal> or + <literal>block-</literal> followed by a device group name, as listed in + <filename>/proc/devices</filename>. The latter is useful to allow-list all current and future + devices belonging to a specific device group at once. The device group is matched according to + filename globbing rules, you may hence use the <literal>*</literal> and <literal>?</literal> + wildcards. (Note that such globbing wildcards are not available for device node path + specifications!) In order to match device nodes by numeric major/minor, use device node paths in + the <filename>/dev/char/</filename> and <filename>/dev/block/</filename> directories. However, + matching devices by major/minor is generally not recommended as assignments are neither stable nor + portable between systems or different kernel versions.</para> + + <para>Examples: <filename>/dev/sda5</filename> is a path to a device node, referring to an ATA or + SCSI block device. <literal>char-pts</literal> and <literal>char-alsa</literal> are specifiers for + all pseudo TTYs and all ALSA sound devices, respectively. <literal>char-cpu/*</literal> is a + specifier matching all CPU related device groups.</para> + + <para>Note that allow lists defined this way should only reference device groups which are + resolvable at the time the unit is started. Any device groups not resolvable then are not added to + the device allow list. In order to work around this limitation, consider extending service units + with a pair of <command>After=modprobe@xyz.service</command> and + <command>Wants=modprobe@xyz.service</command> lines that load the necessary kernel module + implementing the device group if missing. + Example: <programlisting>… +[Unit] +Wants=modprobe@loop.service +After=modprobe@loop.service + +[Service] +DeviceAllow=block-loop +DeviceAllow=/dev/loop-control +…</programlisting></para> + + <xi:include href="cgroup-sandboxing.xml" xpointer="singular"/> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>DevicePolicy=auto|closed|strict</varname></term> + + <listitem> + <para> + Control the policy for allowing device access: + </para> + <variablelist> + <varlistentry> + <term><option>strict</option></term> + <listitem> + <para>means to only allow types of access that are + explicitly specified.</para> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>closed</option></term> + <listitem> + <para>in addition, allows access to standard pseudo + devices including + <filename>/dev/null</filename>, + <filename>/dev/zero</filename>, + <filename>/dev/full</filename>, + <filename>/dev/random</filename>, and + <filename>/dev/urandom</filename>. + </para> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>auto</option></term> + <listitem> + <para> + in addition, allows access to all devices if no + explicit <varname>DeviceAllow=</varname> is present. + This is the default. + </para> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + </variablelist> + + <xi:include href="cgroup-sandboxing.xml" xpointer="singular"/> + + <xi:include href="version-info.xml" xpointer="v208"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>Control Group Management</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>Slice=</varname></term> + + <listitem> + <para>The name of the slice unit to place the unit + in. Defaults to <filename>system.slice</filename> for all + non-instantiated units of all unit types (except for slice + units themselves see below). Instance units are by default + placed in a subslice of <filename>system.slice</filename> + that is named after the template name.</para> + + <para>This option may be used to arrange systemd units in a + hierarchy of slices each of which might have resource + settings applied.</para> + + <para>For units of type slice, the only accepted value for + this setting is the parent slice. Since the name of a slice + unit implies the parent slice, it is hence redundant to ever + set this parameter directly for slice units.</para> + + <para>Special care should be taken when relying on the default slice assignment in templated service units + that have <varname>DefaultDependencies=no</varname> set, see + <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, section + "Default Dependencies" for details.</para> + + <xi:include href="version-info.xml" xpointer="v208"/> + + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>Delegate=</varname></term> + + <listitem> + <para>Turns on delegation of further resource control partitioning to processes of the unit. Units + where this is enabled may create and manage their own private subhierarchy of control groups below + the control group of the unit itself. For unprivileged services (i.e. those using the + <varname>User=</varname> setting) the unit's control group will be made accessible to the relevant + user.</para> + + <para>When enabled the service manager will refrain from manipulating control groups or moving + processes below the unit's control group, so that a clear concept of ownership is established: the + control group tree at the level of the unit's control group and above (i.e. towards the root + control group) is owned and managed by the service manager of the host, while the control group + tree below the unit's control group is owned and managed by the unit itself.</para> + + <para>Takes either a boolean argument or a (possibly empty) list of control group controller names. + If true, delegation is turned on, and all supported controllers are enabled for the unit, making + them available to the unit's processes for management. If false, delegation is turned off entirely + (and no additional controllers are enabled). If set to a list of controllers, delegation is turned + on, and the specified controllers are enabled for the unit. Assigning the empty string will enable + delegation, but reset the list of controllers, and all assignments prior to this will have no + effect. Note that additional controllers other than the ones specified might be made available as + well, depending on configuration of the containing slice unit or other units contained in it. + Defaults to false.</para> + + <para>Note that controller delegation to less privileged code is only safe on the unified control + group hierarchy. Accordingly, access to the specified controllers will not be granted to + unprivileged services on the legacy hierarchy, even when requested.</para> + + <xi:include href="supported-controllers.xml" xpointer="controllers-text" /> + + <para>Not all of these controllers are available on all kernels however, and some are specific to + the unified hierarchy while others are specific to the legacy hierarchy. Also note that the kernel + might support further controllers, which aren't covered here yet as delegation is either not + supported at all for them or not defined cleanly.</para> + + <para>Note that because of the hierarchical nature of cgroup hierarchy, any controllers that are + delegated will be enabled for the parent and sibling units of the unit with delegation.</para> + + <para>For further details on the delegation model consult <ulink + url="https://systemd.io/CGROUP_DELEGATION">Control Group APIs and Delegation</ulink>.</para> + + <xi:include href="version-info.xml" xpointer="v218"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>DelegateSubgroup=</varname></term> + + <listitem> + <para>Place unit processes in the specified subgroup of the unit's control group. Takes a valid + control group name (not a path!) as parameter, or an empty string to turn this feature + off. Defaults to off. The control group name must be usable as filename and avoid conflicts with + the kernel's control group attribute files (i.e. <filename>cgroup.procs</filename> is not an + acceptable name, since the kernel exposes a native control group attribute file by that name). This + option has no effect unless control group delegation is turned on via <varname>Delegate=</varname>, + see above. Note that this setting only applies to "main" processes of a unit, i.e. for services to + <varname>ExecStart=</varname>, but not for <varname>ExecReload=</varname> and similar. If + delegation is enabled, the latter are always placed inside a subgroup named + <filename>.control</filename>. The specified subgroup is automatically created (and potentially + ownership is passed to the unit's configured user/group) when a process is started in it.</para> + + <para>This option is useful to avoid manually moving the invoked process into a subgroup after it + has been started. Since no processes should live in inner nodes of the control group tree it's + almost always necessary to run the main ("supervising") process of a unit that has delegation + turned on in a subgroup.</para> + + <xi:include href="version-info.xml" xpointer="v254"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>DisableControllers=</varname></term> + + <listitem> + <para>Disables controllers from being enabled for a unit's children. If a controller listed is + already in use in its subtree, the controller will be removed from the subtree. This can be used to + avoid configuration in child units from being able to implicitly or explicitly enable a controller. + Defaults to empty.</para> + + <para>Multiple controllers may be specified, separated by spaces. You may also pass + <varname>DisableControllers=</varname> multiple times, in which case each new instance adds another controller + to disable. Passing <varname>DisableControllers=</varname> by itself with no controller name present resets + the disabled controller list.</para> + + <para>It may not be possible to disable a controller after units have been started, if the unit or + any child of the unit in question delegates controllers to its children, as any delegated subtree + of the cgroup hierarchy is unmanaged by systemd.</para> + + <xi:include href="supported-controllers.xml" xpointer="controllers-text" /> + + <xi:include href="version-info.xml" xpointer="v240"/> + </listitem> + </varlistentry> + + </variablelist> + + </refsect2><refsect2><title>Memory Pressure Control</title> + + <variablelist class='unit-directives'> + + <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>, the unit becomes a candidate for monitoring by + <command>systemd-oomd</command>. If the cgroup passes the limits set by + <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> or + the unit configuration, <command>systemd-oomd</command> will select a descendant cgroup and send + <constant>SIGKILL</constant> to all of the processes under it. 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>.</para> + + <para>Setting either of these properties to <option>kill</option> will also result in + <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 a candidate + for <command>systemd-oomd</command> to terminate.</para> + + <xi:include href="version-info.xml" xpointer="v247"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ManagedOOMMemoryPressureLimit=</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 to use the default set by + <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + </para> + + <xi:include href="version-info.xml" xpointer="v247"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ManagedOOMPreference=none|avoid|omit</varname></term> + + <listitem> + <para>Allows deprioritizing or omitting this unit's cgroup as a candidate when + <command>systemd-oomd</command> needs to act. Requires support for extended attributes (see + <citerefentry project='man-pages'><refentrytitle>xattr</refentrytitle><manvolnum>7</manvolnum></citerefentry>) + in order to use <option>avoid</option> or <option>omit</option>.</para> + + <para>When calculating candidates to relieve swap usage, <command>systemd-oomd</command> will + only respect these extended attributes if the unit's cgroup is owned by root.</para> + + <para>When calculating candidates to relieve memory pressure, <command>systemd-oomd</command> + will only respect these extended attributes if the unit's cgroup is owned by root, or if the + unit's cgroup owner, and the owner of the monitored ancestor cgroup are the same. For example, + if <command>systemd-oomd</command> is calculating candidates for <filename>-.slice</filename>, + then extended attributes set on descendants of <filename>/user.slice/user-1000.slice/user@1000.service/</filename> + will be ignored because the descendants are owned by UID 1000, and <filename>-.slice</filename> + is owned by UID 0. But, if calculating candidates for + <filename>/user.slice/user-1000.slice/user@1000.service/</filename>, then extended attributes set + on the descendants would be respected.</para> + + <para>If this property is set to <option>avoid</option>, the service manager will convey this to + <command>systemd-oomd</command>, which will only select this cgroup if there are no other viable + candidates.</para> + + <para>If this property is set to <option>omit</option>, the service manager will convey this to + <command>systemd-oomd</command>, which will ignore this cgroup as a candidate and will not perform + any actions on it.</para> + + <para>It is recommended to use <option>avoid</option> and <option>omit</option> sparingly, as it + can adversely affect <command>systemd-oomd</command>'s kill behavior. Also note that these extended + attributes are not applied recursively to cgroups under this unit's cgroup.</para> + + <para>Defaults to <option>none</option> which means <command>systemd-oomd</command> will rank this + unit's cgroup as defined in + <citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + and <citerefentry><refentrytitle>oomd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + </para> + + <xi:include href="version-info.xml" xpointer="v248"/> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemoryPressureWatch=</varname></term> + + <listitem><para>Controls memory pressure monitoring for invoked processes. Takes one of + <literal>off</literal>, <literal>on</literal>, <literal>auto</literal> or <literal>skip</literal>. If + <literal>off</literal> tells the service not to watch for memory pressure events, by setting the + <varname>$MEMORY_PRESSURE_WATCH</varname> environment variable to the literal string + <filename>/dev/null</filename>. If <literal>on</literal> tells the service to watch for memory + pressure events. This enables memory accounting for the service, and ensures the + <filename>memory.pressure</filename> cgroup attribute file is accessible for reading and writing by the + service's user. It then sets the <varname>$MEMORY_PRESSURE_WATCH</varname> environment variable for + processes invoked by the unit to the file system path to this file. The threshold information + configured with <varname>MemoryPressureThresholdSec=</varname> is encoded in the + <varname>$MEMORY_PRESSURE_WRITE</varname> environment variable. If the <literal>auto</literal> value + is set the protocol is enabled if memory accounting is anyway enabled for the unit, and disabled + otherwise. If set to <literal>skip</literal> the logic is neither enabled, nor disabled and the two + environment variables are not set.</para> + + <para>Note that services are free to use the two environment variables, but it's unproblematic if + they ignore them. Memory pressure handling must be implemented individually in each service, and + usually means different things for different software. For further details on memory pressure + handling see <ulink url="https://systemd.io/MEMORY_PRESSURE">Memory Pressure Handling in + systemd</ulink>.</para> + + <para>Services implemented using + <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> may use + <citerefentry><refentrytitle>sd_event_add_memory_pressure</refentrytitle><manvolnum>3</manvolnum></citerefentry> + to watch for and handle memory pressure events.</para> + + <para>If not explicit set, defaults to the <varname>DefaultMemoryPressureWatch=</varname> setting in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v254"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>MemoryPressureThresholdSec=</varname></term> + + <listitem><para>Sets the memory pressure threshold time for memory pressure monitor as configured via + <varname>MemoryPressureWatch=</varname>. Specifies the maximum allocation latency before a memory + pressure event is signalled to the service, per 2s window. If not specified defaults to the + <varname>DefaultMemoryPressureThresholdSec=</varname> setting in + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> + (which in turn defaults to 200ms). The specified value expects a time unit such as + <literal>ms</literal> or <literal>μs</literal>, see + <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for + details on the permitted syntax.</para> + + <xi:include href="version-info.xml" xpointer="v254"/></listitem> + </varlistentry> + </variablelist> + + </refsect2><refsect2><title>Coredump Control</title> + + <variablelist class='unit-directives'> + + <varlistentry> + <term><varname>CoredumpReceive=</varname></term> + + <listitem><para>Takes a boolean argument. This setting is used to enable coredump forwarding for containers + that belong to this unit's cgroup. Units with <varname>CoredumpReceive=yes</varname> must also be configured + with <varname>Delegate=yes</varname>. Defaults to false.</para> + + <para>When <command>systemd-coredump</command> is handling a coredump for a process from a container, + if the container's leader process is a descendant of a cgroup with <varname>CoredumpReceive=yes</varname> + and <varname>Delegate=yes</varname>, then <command>systemd-coredump</command> will attempt to forward + the coredump to <command>systemd-coredump</command> within the container.</para> + + <xi:include href="version-info.xml" xpointer="v255"/></listitem> + </varlistentry> + + </variablelist> + </refsect2> + </refsect1> + + <refsect1> + <title>History</title> + + <variablelist> + <varlistentry> + <term>systemd 252</term> + <listitem><para> Options for controlling the Legacy Control Group Hierarchy (<ulink + url="https://docs.kernel.org/admin-guide/cgroup-v1/index.html">Control Groups version 1</ulink>) + are now fully deprecated: + <varname>CPUShares=<replaceable>weight</replaceable></varname>, + <varname>StartupCPUShares=<replaceable>weight</replaceable></varname>, + <varname>MemoryLimit=<replaceable>bytes</replaceable></varname>, + <varname>BlockIOAccounting=</varname>, + <varname>BlockIOWeight=<replaceable>weight</replaceable></varname>, + <varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname>, + <varname>BlockIODeviceWeight=<replaceable>device</replaceable> + <replaceable>weight</replaceable></varname>, + <varname>BlockIOReadBandwidth=<replaceable>device</replaceable> + <replaceable>bytes</replaceable></varname>, + <varname>BlockIOWriteBandwidth=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname>. + Please switch to the unified cgroup hierarchy.</para> + + <xi:include href="version-info.xml" xpointer="v252"/></listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <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://docs.kernel.org/admin-guide/cgroup-v2.html">Control Groups v2</ulink>. + </para> + </refsect1> +</refentry> |