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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 02:25:50 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 02:25:50 +0000
commit19f4f86bfed21c5326ed2acebe1163f3a83e832b (patch)
treed59b9989ce55ed23693e80974d94c856f1c2c8b1 /man/systemd.resource-control.xml
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Adding upstream version 241.upstream/241upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?xml version='1.0'?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ SPDX-License-Identifier: LGPL-2.1+
+-->
+
+<refentry id="systemd.resource-control">
+ <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>
+
+ <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>Unified and Legacy Control Group Hierarchies</title>
+
+ <para>The unified control group hierarchy is the new version of kernel control group interface, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>. Depending on the resource type,
+ there are differences in resource control capabilities. Also, because of interface changes, some resource types
+ have separate set of options on the unified hierarchy.</para>
+
+ <para>
+ <variablelist>
+
+ <varlistentry>
+ <term><option>CPU</option></term>
+ <listitem>
+ <para><varname>CPUWeight=</varname> and <varname>StartupCPUWeight=</varname> replace
+ <varname>CPUShares=</varname> and <varname>StartupCPUShares=</varname>, respectively.</para>
+
+ <para>The <literal>cpuacct</literal> controller does not exist separately on the unified hierarchy.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>Memory</option></term>
+ <listitem>
+ <para><varname>MemoryMax=</varname> replaces <varname>MemoryLimit=</varname>. <varname>MemoryLow=</varname>
+ and <varname>MemoryHigh=</varname> are effective only on unified hierarchy.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>IO</option></term>
+ <listitem>
+ <para><varname>IO</varname> prefixed settings are a superset of and replace <varname>BlockIO</varname>
+ prefixed ones. On unified hierarchy, IO resource control also applies to buffered writes.</para>
+ </listitem>
+ </varlistentry>
+
+ </variablelist>
+ </para>
+
+ <para>To ease the transition, there is best-effort translation between the two versions of settings. For each
+ controller, if any of the settings for the unified hierarchy are present, all settings for the legacy hierarchy are
+ ignored. If the resulting settings are for the other type of hierarchy, the configurations are translated before
+ application.</para>
+
+ <para>Legacy control group hierarchy (see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt">cgroups.txt</ulink>), also called cgroup-v1,
+ doesn't allow safe delegation of controllers to unprivileged processes. If the system uses the legacy control group
+ hierarchy, resource control is disabled for systemd user instance, see
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>Units of the types listed above can have settings
+ for resource control configuration:</para>
+
+ <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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CPUWeight=<replaceable>weight</replaceable></varname></term>
+ <term><varname>StartupCPUWeight=<replaceable>weight</replaceable></varname></term>
+
+ <listitem>
+ <para>Assign the specified CPU time weight to the processes executed, if the unified control group hierarchy
+ is used on the system. These options take an integer value and control the <literal>cpu.weight</literal>
+ control group attribute. The allowed range is 1 to 10000. Defaults to 100. For details about this control
+ group attribute, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink> and <ulink
+ url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.
+ The available CPU time is split up among all units within one slice relative to their CPU time weight.</para>
+
+ <para>While <varname>StartupCPUWeight=</varname> only applies to the startup phase of the system,
+ <varname>CPUWeight=</varname> applies to normal runtime of the system, and if the former is not set also to
+ the startup phase. Using <varname>StartupCPUWeight=</varname> allows prioritizing specific services at
+ boot-up differently than during normal runtime.</para>
+
+ <para>These settings replace <varname>CPUShares=</varname> and <varname>StartupCPUShares=</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CPUQuota=</varname></term>
+
+ <listitem>
+ <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 &gt; 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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink> and <ulink
+ url="https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt">sched-bwc.txt</ulink>.</para>
+
+ <para>Example: <varname>CPUQuota=20%</varname> ensures that the executed processes will never get more than
+ 20% CPU time on one CPU.</para>
+
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MemoryAccounting=</varname></term>
+
+ <listitem>
+ <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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MemoryMin=<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. 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/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>This setting is supported only if the unified control group hierarchy is used and disables
+ <varname>MemoryLimit=</varname>.</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>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. This controls the <literal>memory.low</literal> control group attribute. For details about this
+ control group attribute, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>This setting is supported only if the unified control group hierarchy is used and disables
+ <varname>MemoryLimit=</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MemoryHigh=<replaceable>bytes</replaceable></varname></term>
+
+ <listitem>
+ <para>Specify the high 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 limit is applied. This controls the
+ <literal>memory.high</literal> control group attribute. For details about this control group attribute, see
+ <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>This setting is supported only if the unified control group hierarchy is used and disables
+ <varname>MemoryLimit=</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MemoryMax=<replaceable>bytes</replaceable></varname></term>
+
+ <listitem>
+ <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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>This setting replaces <varname>MemoryLimit=</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MemorySwapMax=<replaceable>bytes</replaceable></varname></term>
+
+ <listitem>
+ <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. This controls the
+ <literal>memory.swap.max</literal> control group attribute. For details about this control group attribute,
+ see <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>This setting is supported only if the unified control group hierarchy is used and disables
+ <varname>MemoryLimit=</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>TasksAccounting=</varname></term>
+
+ <listitem>
+ <para>Turn on task accounting for this unit. Takes a
+ boolean argument. If enabled, the system manager will keep
+ track of the number of tasks in the unit. The number of
+ tasks accounted this way includes both kernel threads and
+ userspace processes, with each thread counting
+ 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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>TasksMax=<replaceable>N</replaceable></varname></term>
+
+ <listitem>
+ <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, see
+ <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/pids.txt">pids.txt</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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IOAccounting=</varname></term>
+
+ <listitem>
+ <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>
+
+ <para>This setting replaces <varname>BlockIOAccounting=</varname> and disables settings prefixed with
+ <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IOWeight=<replaceable>weight</replaceable></varname></term>
+ <term><varname>StartupIOWeight=<replaceable>weight</replaceable></varname></term>
+
+ <listitem>
+ <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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>. The available I/O
+ bandwidth is split up among all units within one slice relative to their block I/O weight.</para>
+
+ <para>While <varname>StartupIOWeight=</varname> only applies
+ to the startup phase 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
+ phase. This allows prioritizing specific services at boot-up
+ differently than during runtime.</para>
+
+ <para>These settings replace <varname>BlockIOWeight=</varname> and <varname>StartupBlockIOWeight=</varname>
+ and disable settings prefixed with <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term>
+
+ <listitem>
+ <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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>This setting replaces <varname>BlockIODeviceWeight=</varname> and disables settings prefixed with
+ <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para>
+ </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>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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.
+ </para>
+
+ <para>These settings replace <varname>BlockIOReadBandwidth=</varname> and
+ <varname>BlockIOWriteBandwidth=</varname> and disable settings prefixed with <varname>BlockIO</varname> or
+ <varname>StartupBlockIO</varname>.</para>
+ </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>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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.
+ </para>
+
+ <para>These settings are supported only if the unified control group hierarchy is used and disable settings
+ prefixed with <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IODeviceLatencyTargetSec=<replaceable>device</replaceable> <replaceable>target</replaceable></varname></term>
+
+ <listitem>
+ <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://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para>
+
+ <para>Implies <literal>IOAccounting=yes</literal>.</para>
+
+ <para>These settings are supported only if the unified control group hierarchy is used.</para>
+ </listitem>
+ </varlistentry>
+
+ <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>
+ </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 address range network traffic filtering for packets sent and received over AF_INET and AF_INET6
+ sockets. Both directives take a space separated list of IPv4 or IPv6 addresses, each optionally suffixed
+ with an address prefix length (separated by a <literal>/</literal> character). If the latter is omitted, the
+ address is considered a host address, i.e. the prefix covers the whole address (32 for IPv4, 128 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 all access lists are
+ empty. When configured the lists are enforced as follows:</para>
+
+ <itemizedlist>
+ <listitem><para>Access will be granted in case its destination/source address matches any entry in the
+ <varname>IPAddressAllow=</varname> setting.</para></listitem>
+
+ <listitem><para>Otherwise, access will be denied in case its destination/source address matches any entry
+ in the <varname>IPAddressDeny=</varname> setting.</para></listitem>
+
+ <listitem><para>Otherwise, access will be granted.</para></listitem>
+ </itemizedlist>
+
+ <para>In order to implement a whitelisting 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, however it often makes sense to maintain one list more open and the other
+ one more restricted, depending on the usecase.</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>
+ </listitem>
+ </varlistentry>
+
+ <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 node(s) by the unit
+ (<emphasis>m</emphasis>knod), respectively. This controls
+ the <literal>devices.allow</literal> and
+ <literal>devices.deny</literal> control group
+ attributes. For details about these control group
+ attributes, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v1/devices.txt">devices.txt</ulink>.</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
+ whitelist 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. 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>
+ </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>
+ </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>
+ </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>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+
+ <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>
+
+ </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. 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 above the unit's control group (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. Takes either a boolean argument or a 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. Note that additional controllers than
+ the ones specified might be made available as well, depending on configuration of the containing slice unit
+ or other units contained in it. Note that assigning the empty string will enable delegation, but reset the
+ list of controllers, all assignments prior to this will have no effect. 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>
+
+ <para>The following controller names may be specified: <option>cpu</option>, <option>cpuacct</option>,
+ <option>io</option>, <option>blkio</option>, <option>memory</option>, <option>devices</option>,
+ <option>pids</option>. 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>For further details on the delegation model consult <ulink
+ url="https://systemd.io/CGROUP_DELEGATION">Control Group APIs and Delegation</ulink>.</para>
+ </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 child units being
+ able to implicitly or explicitly enable a controller. Defaults to not disabling any controllers.</para>
+
+ <para>It may not be possible to successfully disable a controller 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>
+
+ <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>Valid controllers are <option>cpu</option>, <option>cpuacct</option>, <option>io</option>,
+ <option>blkio</option>, <option>memory</option>, <option>devices</option>, and <option>pids</option>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Deprecated Options</title>
+
+ <para>The following options are deprecated. Use the indicated superseding options instead:</para>
+
+ <variablelist class='unit-directives'>
+
+ <varlistentry>
+ <term><varname>CPUShares=<replaceable>weight</replaceable></varname></term>
+ <term><varname>StartupCPUShares=<replaceable>weight</replaceable></varname></term>
+
+ <listitem>
+ <para>Assign the specified CPU time share weight to the processes executed. These options take an integer
+ value and control the <literal>cpu.shares</literal> control group attribute. The allowed range is 2 to
+ 262144. Defaults to 1024. For details about this control group attribute, see <ulink
+ url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.
+ The available CPU time is split up among all units within one slice relative to their CPU time share
+ weight.</para>
+
+ <para>While <varname>StartupCPUShares=</varname> only applies to the startup phase of the system,
+ <varname>CPUShares=</varname> applies to normal runtime of the system, and if the former is not set also to
+ the startup phase. Using <varname>StartupCPUShares=</varname> allows prioritizing specific services at
+ boot-up differently than during normal runtime.</para>
+
+ <para>Implies <literal>CPUAccounting=yes</literal>.</para>
+
+ <para>These settings are deprecated. Use <varname>CPUWeight=</varname> and
+ <varname>StartupCPUWeight=</varname> instead.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MemoryLimit=<replaceable>bytes</replaceable></varname></term>
+
+ <listitem>
+ <para>Specify the limit on maximum memory usage of the executed processes. The limit specifies how much
+ process and kernel memory can be used by tasks in this unit. 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.limit_in_bytes</literal> control group attribute. For details about this control group
+ attribute, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt">memory.txt</ulink>.</para>
+
+ <para>Implies <literal>MemoryAccounting=yes</literal>.</para>
+
+ <para>This setting is deprecated. Use <varname>MemoryMax=</varname> instead.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>BlockIOAccounting=</varname></term>
+
+ <listitem>
+ <para>Turn on Block I/O accounting for this unit, if the legacy 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>DefaultBlockIOAccounting=</varname> in
+ <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+ <para>This setting is deprecated. Use <varname>IOAccounting=</varname> instead.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>BlockIOWeight=<replaceable>weight</replaceable></varname></term>
+ <term><varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname></term>
+
+ <listitem><para>Set the default overall block I/O weight for the executed processes, if the legacy control
+ group hierarchy is used on the system. Takes a single weight value (between 10 and 1000) to set the default
+ block I/O weight. This controls the <literal>blkio.weight</literal> control group attribute, which defaults to
+ 500. For details about this control group attribute, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>.
+ The available I/O bandwidth is split up among all units within one slice relative to their block I/O
+ weight.</para>
+
+ <para>While <varname>StartupBlockIOWeight=</varname> only
+ applies to the startup phase of the system,
+ <varname>BlockIOWeight=</varname> applies to the later runtime
+ of the system, and if the former is not set also to the
+ startup phase. This allows prioritizing specific services at
+ boot-up differently than during runtime.</para>
+
+ <para>Implies
+ <literal>BlockIOAccounting=yes</literal>.</para>
+
+ <para>These settings are deprecated. Use <varname>IOWeight=</varname> and <varname>StartupIOWeight=</varname>
+ instead.</para>
+
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>BlockIODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term>
+
+ <listitem>
+ <para>Set the per-device overall block I/O weight for the executed processes, if the legacy 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 10 and 1000. (Example: "/dev/sda 500"). 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>blkio.weight_device</literal> control group
+ attribute, which defaults to 1000. Use this option multiple times to set weights for multiple devices. For
+ details about this control group attribute, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>.</para>
+
+ <para>Implies
+ <literal>BlockIOAccounting=yes</literal>.</para>
+
+ <para>This setting is deprecated. Use <varname>IODeviceWeight=</varname> instead.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>BlockIOReadBandwidth=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term>
+ <term><varname>BlockIOWriteBandwidth=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term>
+
+ <listitem>
+ <para>Set the per-device overall block I/O bandwidth limit for the executed processes, if the legacy control
+ group hierarchy is used on the system. 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>blkio.throttle.read_bps_device</literal> and <literal>blkio.throttle.write_bps_device</literal>
+ control group attributes. Use this option multiple times to set bandwidth limits for multiple devices. For
+ details about these control group attributes, see <ulink
+ url="https://www.kernel.org/doc/Documentation/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>.
+ </para>
+
+ <para>Implies
+ <literal>BlockIOAccounting=yes</literal>.</para>
+
+ <para>These settings are deprecated. Use <varname>IOReadBandwidthMax=</varname> and
+ <varname>IOWriteBandwidthMax=</varname> instead.</para>
+ </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>,
+ The documentation for control groups and specific controllers in the Linux kernel:
+ <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt">cgroups.txt</ulink>,
+ <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/cpuacct.txt">cpuacct.txt</ulink>,
+ <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt">memory.txt</ulink>,
+ <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>.
+ <ulink url="https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt">sched-bwc.txt</ulink>.
+ </para>
+ </refsect1>
+</refentry>