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<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<refentry id="systemd.resource-control">
<refentryinfo>
<title>systemd.resource-control</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.resource-control</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.resource-control</refname>
<refpurpose>Resource control 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 for resource control of spawned
processes. Internally, this relies on the Control Groups
kernel concept for organizing processes in a hierarchial 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
resource control configuration options are configured in the
[Slice], [Scope], [Service], [Socket], [Mount], or [Swap]
sections, depending on the unit type.</para>
<para>See the <ulink
url="http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/">New
Control Group Interfaces</ulink> for an introduction on how to make
use of resource control APIs from programs.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>Units of the types listed above can have settings
for resource control 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. The system default for this
setting maybe controlled with
<varname>DefaultCPUAccounting=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUShares=<replaceable>weight</replaceable></varname></term>
<listitem>
<para>Assign the specified 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>
The available CPU time is split up among all units within a
slice relative to their CPU time share weight.</para>
<para>Implies <literal>CPUAccounting=true</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUQuota=</varname></term>
<listitem>
<para>Assign the specified CPU time quota to the processes
executed. Takes a percentage value (suffixed with "%") or an
absolute time (suffixed by one of the common time units, us,
ms, s, ...). The percentage specifies how much CPU time the
unit shall get at maximum, relative to the total CPU time
available on one CPU. Use values > 100% for alloting CPU
time on more than one CPU. If an absolute time is specified
the processes of this unit will get this much absolute time
within each quota period, at maximum. This controls the
<literal>cpu.cfs_quota_us</literal> control group
attribute. 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>Example: <varname>CPUShares=20%</varname> ensures that
the executed processes will never get more than 20% CPU time
on one CPU.</para>
<para>Implies <literal>CPUAccounting=true</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUQuotaPeriodSec=</varname></term>
<listitem>
<para>Specify the CPU quota period to use. Defaults to
100ms. This controls the <literal>cpu.cfs_period_us</literal>
control group attribute. 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 its parent slices. The system default for this setting
maybe controlled with
<varname>DefaultMemoryAccounting=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>MemoryLimit=<replaceable>bytes</replaceable></varname></term>
<listitem>
<para>Specify the limit on maximum memory usage of the
executed processes. The limit specifies how much process and
kernel memory can be used by tasks in this unit. 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> control group
attribute. For details about this control group attribute,
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. The system default for this
setting maybe controlled with
<varname>DefaultBlockIOAccounting=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</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, to the base of
1000. (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 specifier 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(s) 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>
<para>The device node specifier is either a path to a device
node in the file system, starting with
<filename>/dev/</filename>, or a string starting with either
<literal>char-</literal> or <literal>block-</literal>
followed by a device group name, as listed in
<filename>/proc/devices</filename>. The latter is useful to
whitelist all current and future devices belonging to a
specific device group at once. The device group is matched
according to file name globbing rules, you may hence use the
<literal>*</literal> and <literal>?</literal>
wildcards. Examples: <filename>/dev/sda5</filename> is a
path to a device node, referring to an ATA or SCSI block
device. <literal>char-pts</literal> and
<literal>char-alsa</literal> are specifiers for all pseudo
TTYs and all ALSA sound devices,
respectively. <literal>char-cpu/*</literal> is a specifier
matching all CPU related device groups.</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>
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