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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>