<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>
+ <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>
<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>
<refsect1>
<title>Options</title>
- <para>Units of the types listed above can have settings
- for resource control configuration:</para>
+ <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'>
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>
<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
- 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>
+ <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
<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>
<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
<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>
<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].
<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>
<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>
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>
- <varlistentry>
- <term><varname>AllowedMemoryNodes=</varname></term>
- <term><varname>StartupAllowedMemoryNodes=</varname></term>
-
- <listitem>
- <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>
+ </variablelist>
- <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>
+ </refsect2><refsect2><title>Memory Accounting and Control</title>
- <para>This setting is supported only with the unified control group hierarchy.</para>
- </listitem>
- </varlistentry>
+ <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
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></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.
<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>.
+ <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,
<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>
<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>
<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>
<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
<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>
<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
<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>
<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
<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>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
+ <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>
<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
<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>
<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,
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>
<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
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>
<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
</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>
<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
</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>
<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
<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>
<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>
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 usecase.</para>
+ 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>
them for IP security.</para>
<xi:include href="cgroup-sandboxing.xml" xpointer="singular"/>
- </listitem>
- </varlistentry>
-
- <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 usecase.</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>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BPFProgram=<replaceable>type</replaceable><constant>:</constant><replaceable>program-path</replaceable></varname></term>
- <listitem>
- <para>Add a custom cgroup BPF program.</para>
-
- <para><varname>BPFProgram=</varname> allows attaching BPF hooks to the cgroup of a systemd unit.
- (This generalizes the functionality exposed via <varname>IPEgressFilterPath=</varname> for egress and
- <varname>IPIngressFilterPath=</varname> for ingress.)
- 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"/>.
- For general BPF documentation please refer to <ulink url="https://docs.kernel.org/bpf/index.html"/>.</para>
-
- <para>The specification of BPF program consists of a <replaceable>type</replaceable> followed by a
- <replaceable>program-path</replaceable> with <literal>:</literal> as the separator:
- <replaceable>type</replaceable><constant>:</constant><replaceable>program-path</replaceable>.</para>
-
- <para><replaceable>type</replaceable> is the string name of BPF attach type also used in
- <command>bpftool</command>. <replaceable>type</replaceable> can 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>, <constant>setsockopt</constant>.</para>
-
- <para>Setting <varname>BPFProgram=</varname> to an empty value makes previous assignments ineffective.</para>
- <para>Multiple assignments of the same <replaceable>type</replaceable>:<replaceable>program-path</replaceable>
- value have the same effect as a single assignment: the program with the path <replaceable>program-path</replaceable>
- will be attached to cgroup hook <replaceable>type</replaceable> 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="v235"/>
</listitem>
</varlistentry>
…</programlisting></para>
<xi:include href="cgroup-sandboxing.xml" xpointer="singular"/>
+
+ <xi:include href="version-info.xml" xpointer="v249"/>
</listitem>
</varlistentry>
</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>
…</programlisting></para>
<xi:include href="cgroup-sandboxing.xml" xpointer="singular"/>
+
+ <xi:include href="version-info.xml" xpointer="v208"/>
</listitem>
</varlistentry>
<listitem>
<para>means to only allow types of access that are
explicitly specified.</para>
+
+ <xi:include href="version-info.xml" xpointer="v208"/>
</listitem>
</varlistentry>
<filename>/dev/random</filename>, and
<filename>/dev/urandom</filename>.
</para>
+
+ <xi:include href="version-info.xml" xpointer="v208"/>
</listitem>
</varlistentry>
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>
<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>
<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>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>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>DisableControllers=</varname></term>
+ <term><varname>DelegateSubgroup=</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>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>
- <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>
+ <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>
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>
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>
<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>
<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></listitem>
+ Please switch to the unified cgroup hierarchy.</para>
+
+ <xi:include href="version-info.xml" xpointer="v252"/></listitem>
</varlistentry>
</variablelist>
</refsect1>
projects / thirdparty / systemd.git / blobdiff