man/systemd.slice.xml

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   8   This file is part of systemd.
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  10   Copyright 2013 Zbigniew Jędrzejewski-Szmek
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  25
  26 <refentry id="systemd.slice">
  27   <refentryinfo>
  28     <title>systemd.slice</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>systemd.slice</refentrytitle>
  43     <manvolnum>5</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>systemd.slice</refname>
  48     <refpurpose>Slice unit configuration</refpurpose>
  49   </refnamediv>
  50
  51   <refsynopsisdiv>
  52     <para><filename><replaceable>slice</replaceable>.slice</filename></para>
  53   </refsynopsisdiv>
  54
  55   <refsect1>
  56     <title>Description</title>
  57
  58     <para>A unit configuration file whose name ends in <literal>.slice</literal> encodes information about a slice
  59     unit. A slice unit is a concept for hierarchically managing resources of a group of processes. This management is
  60     performed by creating a node in the Linux Control Group (cgroup) tree. Units that manage processes (primarily scope
  61     and service units) may be assigned to a specific slice. For each slice, certain resource limits may be set that
  62     apply to all processes of all units contained in that slice. Slices are organized hierarchically in a tree. The
  63     name of the slice encodes the location in the tree. The name consists of a dash-separated series of names, which
  64     describes the path to the slice from the root slice. The root slice is named <filename>-.slice</filename>. Example:
  65     <filename>foo-bar.slice</filename> is a slice that is located within <filename>foo.slice</filename>, which in turn
  66     is located in the root slice <filename>-.slice</filename>.
  67     </para>
  68
  69     <para>Note that slice units cannot be templated, nor is possible to add multiple names to a slice unit by creating
  70     additional symlinks to its unit file.</para>
  71
  72     <para>By default, service and scope units are placed in
  73     <filename>system.slice</filename>, virtual machines and containers
  74     registered with
  75     <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  76     are found in <filename>machine.slice</filename>, and user sessions
  77     handled by
  78     <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  79     in <filename>user.slice</filename>. See
  80     <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  81     for more information.</para>
  82
  83     <para>See
  84     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  85     for the common options of all unit configuration
  86     files. The common configuration items are configured
  87     in the generic [Unit] and [Install] sections. The
  88     slice specific configuration options are configured in
  89     the [Slice] section. Currently, only generic resource control settings
  90     as described in
  91     <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> are allowed.
  92     </para>
  93
  94     <para>See the <ulink
  95     url="https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/">New
  96     Control Group Interfaces</ulink> for an introduction on how to make
  97     use of slice units from programs.</para>
  98   </refsect1>
  99
 100   <refsect1>
 101     <title>Implicit Dependencies</title>
 102
 103     <para>The following dependencies are implicitly added:</para>
 104
 105     <itemizedlist>
 106       <listitem><para>Slice units automatically gain dependencies of type
 107       <varname>After=</varname> and <varname>Requires=</varname> on
 108       their immediate parent slice unit.</para></listitem>
 109     </itemizedlist>
 110   </refsect1>
 111
 112   <refsect1>
 113     <title>Default Dependencies</title>
 114
 115     <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
 116
 117     <itemizedlist>
 118       <listitem><para>Slice units will automatically have dependencies of type <varname>Conflicts=</varname> and
 119       <varname>Before=</varname> on
 120       <filename>shutdown.target</filename>. These ensure that slice units are removed prior to system shutdown.
 121       Only slice units involved with late system shutdown should disable
 122       <varname>DefaultDependencies=</varname> option.</para></listitem>
 123     </itemizedlist>
 124   </refsect1>
 125
 126   <refsect1>
 127     <title>See Also</title>
 128     <para>
 129       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 130       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 131       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 132       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 133       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 134       <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 135       <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 136     </para>
 137   </refsect1>
 138
 139 </refentry>