man/systemd.cgroup.xml

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<refentry id="systemd.cgroup">
  <refentryinfo>
    <title>systemd.cgroup</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Lennart</firstname>
        <surname>Poettering</surname>
        <email>lennart@poettering.net</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd.cgroup</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd.cgroup</refname>
    <refpurpose>Control Group configuration 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 which configure the control group settings
    for spawned processes.</para>

    <para>Control Groups is a concept for organizing processes in a
    hierarch 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
    execution-specific configuration options are configured in the
    [Slice], [Scope], [Service], [Socket], [Mount], or [Swap]
    sections, depending on the unit type.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>Units of the types listed above can have settings
    for cgroup 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 might also implicitly turn it on for all units
          contained in the same slice and for all its parent slices and
          the units contained therein.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CPUShares=<replaceable>weight</replaceable></varname></term>

        <listitem>
          <para>Assign the specified overall CPU time share weight to
          the processes executed. Takes an integer value. This
          controls the <literal>cpu.shares</literal> control group
          attribute, which 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>.</para>

          <para>Implies <literal>CPUAccounting=true</literal>.</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 might also implicitly turn it on for
          all units contained in the same slice and for all its parent
          slices and the units contained therein.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MemoryLimit=<replaceable>bytes</replaceable></varname></term>
        <term><varname>MemorySoftLimit=<replaceable>bytes</replaceable></varname></term>

        <listitem>
          <para>Specify the hard and soft limits on maximum memory
          usage of the executed processes. The "hard" limit specifies
          how much process and kernel memory can be used by tasks in
          this unit, when there is no memory contention. If the kernel
          detects memory contention, memory reclaim will be performed
          until the memory usage is within the "soft" limit. 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. This controls the
          <literal>memory.limit_in_bytes</literal> and
          <literal>memory.soft_limit_in_bytes</literal> control group
          attributes. For details about these control group attributes,
          see <ulink
          url="https://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>.</para>

          <para>Implies <literal>MemoryAccounting=true</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BlockIOAccounting=</varname></term>

        <listitem>
          <para>Turn on Block IO accounting for this unit. Takes a
          boolean argument. Note that turning on block IO accounting
          for one unit might also implicitly turn it on for all units
          contained in the same slice and all for its parent slices and
          the units contained therein.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BlockIOWeight=<replaceable>weight</replaceable></varname></term>

        <listitem><para>Set the default
        overall block IO weight for the
        executed processes. Takes a single
        weight value (between 10 and 1000) to
        set the default block IO weight. This
        controls the
        <literal>blkio.weight</literal>
        control group attribute, which
        defaults to 1000. For details about
        this control group attribute, see
        <ulink
            url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para>

        <para>Implies
        <literal>BlockIOAccounting=true</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BlockIODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term>

        <listitem>
          <para>Set the per-device overall block IO weight for the
          executed processes. 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/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para>

          <para>Implies
          <literal>BlockIOAccounting=true</literal>.</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 IO bandwidth limit
          for the executed processes. 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 (Example:
          "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This
          controls the <literal>blkio.read_bps_device</literal> and
          <literal>blkio.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/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.
          </para>

          <para>Implies
          <literal>BlockIOAccounting=true</literal>.</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 path (such as <filename>/dev/null</filename>)
          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 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/cgroups/devices.txt">devices.txt</ulink>.</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>
        </listitem>
      </varlistentry>

    </variablelist>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</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.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/cgroups/cgroups.txt">cgroups.txt</ulink>,
      <ulink url="https://www.kernel.org/doc/Documentation/cgroups/cpuacct.txt">cpuacct.txt</ulink>,
      <ulink url="https://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>,
      <ulink url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.
    </para>
  </refsect1>
</refentry>