man/systemd.slice.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="systemd.slice">
  10   <refentryinfo>
  11     <title>systemd.slice</title>
  12     <productname>systemd</productname>
  13   </refentryinfo>
  14
  15   <refmeta>
  16     <refentrytitle>systemd.slice</refentrytitle>
  17     <manvolnum>5</manvolnum>
  18   </refmeta>
  19
  20   <refnamediv>
  21     <refname>systemd.slice</refname>
  22     <refpurpose>Slice unit configuration</refpurpose>
  23   </refnamediv>
  24
  25   <refsynopsisdiv>
  26     <para><filename><replaceable>slice</replaceable>.slice</filename></para>
  27   </refsynopsisdiv>
  28
  29   <refsect1>
  30     <title>Description</title>
  31
  32     <para>A unit configuration file whose name ends in <literal>.slice</literal> encodes information about a slice
  33     unit. A slice unit is a concept for hierarchically managing resources of a group of processes. This management is
  34     performed by creating a node in the Linux Control Group (cgroup) tree. Units that manage processes (primarily scope
  35     and service units) may be assigned to a specific slice. For each slice, certain resource limits may be set that
  36     apply to all processes of all units contained in that slice. Slices are organized hierarchically in a tree. The
  37     name of the slice encodes the location in the tree. The name consists of a dash-separated series of names, which
  38     describes the path to the slice from the root slice. The root slice is named <filename>-.slice</filename>. Example:
  39     <filename>foo-bar.slice</filename> is a slice that is located within <filename>foo.slice</filename>, which in turn
  40     is located in the root slice <filename>-.slice</filename>.
  41     </para>
  42
  43     <para>Note that slice units cannot be templated, nor is possible to add multiple names to a slice unit by creating
  44     additional symlinks to its unit file.</para>
  45
  46     <para>By default, service and scope units are placed in
  47     <filename>system.slice</filename>, virtual machines and containers
  48     registered with
  49     <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  50     are found in <filename>machine.slice</filename>, and user sessions
  51     handled by
  52     <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  53     in <filename>user.slice</filename>. See
  54     <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  55     for more information.</para>
  56
  57     <para>See
  58     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  59     for the common options of all unit configuration
  60     files. The common configuration items are configured
  61     in the generic [Unit] and [Install] sections. The
  62     slice specific configuration options are configured in
  63     the [Slice] section. Currently, only generic resource control settings
  64     as described in
  65     <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> are allowed.
  66     </para>
  67
  68     <para>See the <ulink
  69     url="https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/">New
  70     Control Group Interfaces</ulink> for an introduction on how to make
  71     use of slice units from programs.</para>
  72   </refsect1>
  73
  74   <refsect1>
  75     <title>Automatic Dependencies</title>
  76
  77     <refsect2>
  78       <title>Implicit Dependencies</title>
  79
  80       <para>The following dependencies are implicitly added:</para>
  81
  82       <itemizedlist>
  83         <listitem><para>Slice units automatically gain dependencies of type
  84         <varname>After=</varname> and <varname>Requires=</varname> on
  85         their immediate parent slice unit.</para></listitem>
  86       </itemizedlist>
  87     </refsect2>
  88
  89     <refsect2>
  90       <title>Default Dependencies</title>
  91
  92       <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
  93
  94       <itemizedlist>
  95         <listitem><para>Slice units will automatically have dependencies of type <varname>Conflicts=</varname> and
  96         <varname>Before=</varname> on
  97         <filename>shutdown.target</filename>. These ensure that slice units are removed prior to system shutdown.
  98         Only slice units involved with late system shutdown should disable
  99         <varname>DefaultDependencies=</varname> option.</para></listitem>
 100       </itemizedlist>
 101     </refsect2>
 102   </refsect1>
 103
 104   <refsect1>
 105     <title>See Also</title>
 106     <para>
 107       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 108       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 109       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 110       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 111       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 112       <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 113       <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 114     </para>
 115   </refsect1>
 116
 117 </refentry>