man/systemd.slice.xml

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   8   Copyright © 2013 Zbigniew Jędrzejewski-Szmek
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  10
  11 <refentry id="systemd.slice">
  12   <refentryinfo>
  13     <title>systemd.slice</title>
  14     <productname>systemd</productname>
  15
  16     <authorgroup>
  17       <author>
  18         <contrib>Developer</contrib>
  19         <firstname>Lennart</firstname>
  20         <surname>Poettering</surname>
  21         <email>lennart@poettering.net</email>
  22       </author>
  23     </authorgroup>
  24   </refentryinfo>
  25
  26   <refmeta>
  27     <refentrytitle>systemd.slice</refentrytitle>
  28     <manvolnum>5</manvolnum>
  29   </refmeta>
  30
  31   <refnamediv>
  32     <refname>systemd.slice</refname>
  33     <refpurpose>Slice unit configuration</refpurpose>
  34   </refnamediv>
  35
  36   <refsynopsisdiv>
  37     <para><filename><replaceable>slice</replaceable>.slice</filename></para>
  38   </refsynopsisdiv>
  39
  40   <refsect1>
  41     <title>Description</title>
  42
  43     <para>A unit configuration file whose name ends in <literal>.slice</literal> encodes information about a slice
  44     unit. A slice unit is a concept for hierarchically managing resources of a group of processes. This management is
  45     performed by creating a node in the Linux Control Group (cgroup) tree. Units that manage processes (primarily scope
  46     and service units) may be assigned to a specific slice. For each slice, certain resource limits may be set that
  47     apply to all processes of all units contained in that slice. Slices are organized hierarchically in a tree. The
  48     name of the slice encodes the location in the tree. The name consists of a dash-separated series of names, which
  49     describes the path to the slice from the root slice. The root slice is named <filename>-.slice</filename>. Example:
  50     <filename>foo-bar.slice</filename> is a slice that is located within <filename>foo.slice</filename>, which in turn
  51     is located in the root slice <filename>-.slice</filename>.
  52     </para>
  53
  54     <para>Note that slice units cannot be templated, nor is possible to add multiple names to a slice unit by creating
  55     additional symlinks to its unit file.</para>
  56
  57     <para>By default, service and scope units are placed in
  58     <filename>system.slice</filename>, virtual machines and containers
  59     registered with
  60     <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  61     are found in <filename>machine.slice</filename>, and user sessions
  62     handled by
  63     <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  64     in <filename>user.slice</filename>. See
  65     <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  66     for more information.</para>
  67
  68     <para>See
  69     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  70     for the common options of all unit configuration
  71     files. The common configuration items are configured
  72     in the generic [Unit] and [Install] sections. The
  73     slice specific configuration options are configured in
  74     the [Slice] section. Currently, only generic resource control settings
  75     as described in
  76     <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> are allowed.
  77     </para>
  78
  79     <para>See the <ulink
  80     url="https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/">New
  81     Control Group Interfaces</ulink> for an introduction on how to make
  82     use of slice units from programs.</para>
  83   </refsect1>
  84
  85   <refsect1>
  86     <title>Automatic Dependencies</title>
  87
  88     <refsect2>
  89       <title>Implicit Dependencies</title>
  90
  91       <para>The following dependencies are implicitly added:</para>
  92
  93       <itemizedlist>
  94         <listitem><para>Slice units automatically gain dependencies of type
  95         <varname>After=</varname> and <varname>Requires=</varname> on
  96         their immediate parent slice unit.</para></listitem>
  97       </itemizedlist>
  98     </refsect2>
  99
 100     <refsect2>
 101       <title>Default Dependencies</title>
 102
 103       <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
 104
 105       <itemizedlist>
 106         <listitem><para>Slice units will automatically have dependencies of type <varname>Conflicts=</varname> and
 107         <varname>Before=</varname> on
 108         <filename>shutdown.target</filename>. These ensure that slice units are removed prior to system shutdown.
 109         Only slice units involved with late system shutdown should disable
 110         <varname>DefaultDependencies=</varname> option.</para></listitem>
 111       </itemizedlist>
 112     </refsect2>
 113   </refsect1>
 114
 115   <refsect1>
 116     <title>See Also</title>
 117     <para>
 118       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 119       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 120       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 121       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 122       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 123       <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 124       <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 125     </para>
 126   </refsect1>
 127
 128 </refentry>