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systemd/man/systemd.resource-control.xml
Lennart Poettering 0af20ea2ee core: add new DefaultTasksMax= setting for system.conf
This allows initializing the TasksMax= setting of all units by default
to some fixed value, instead of leaving it at infinity as before.
2015-11-13 19:50:52 +01:00

503 lines
23 KiB
XML

<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!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 hierarchical 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>Automatic Dependencies</title>
<para>Units with the <varname>Slice=</varname> setting set get
automatic <varname>Requires=</varname> and
<varname>After=</varname> dependencies on the specified slice
unit.</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 will 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 may be 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>
<term><varname>StartupCPUShares=<replaceable>weight</replaceable></varname></term>
<listitem>
<para>Assign the specified CPU time share weight to the
processes executed. These options take an integer value and
control the <literal>cpu.shares</literal> control group
attribute. The allowed range is 2 to 262144. 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
one slice relative to their CPU time share weight.</para>
<para>While <varname>StartupCPUShares=</varname> only
applies to the startup phase of the system,
<varname>CPUShares=</varname> applies to normal runtime of
the system, and if the former is not set also to the startup
phase. Using <varname>StartupCPUShares=</varname> allows
prioritizing specific services at boot-up differently than
during normal runtime.</para>
<para>These options imply
<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 "%". 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 &gt; 100% for allotting CPU time on more than
one CPU. 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>CPUQuota=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>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 will 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 may be 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. If assigned the special value
<literal>infinity</literal>, no memory limit is applied. 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>TasksAccounting=</varname></term>
<listitem>
<para>Turn on task accounting for this unit. Takes a
boolean argument. If enabled, the system manager will keep
track of the number of tasks in the unit. The number of
tasks accounted this way includes both kernel threads and
userspace processes, with each thread counting
individually. Note that turning on tasks accounting for one
unit will 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
may be controlled with
<varname>DefaultTasksAccounting=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>TasksMax=<replaceable>N</replaceable></varname></term>
<listitem>
<para>Specify the maximum number of tasks that may be
created in the unit. This ensures that the number of tasks
accounted for the unit (see above) stays below a specific
limit. If assigned the special value
<literal>infinity</literal>, no tasks limit is applied. This
controls the <literal>pids.max</literal> control group
attribute. For details about this control group attribute,
see <ulink
url="https://www.kernel.org/doc/Documentation/cgroups/pids.txt">pids.txt</ulink>.</para>
<para>Implies <literal>TasksAccounting=true</literal>. The
system default for this setting may be controlled with
<varname>DefaultTasksMax=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>BlockIOAccounting=</varname></term>
<listitem>
<para>Turn on Block I/O accounting for this unit. Takes a
boolean argument. Note that turning on block I/O accounting
for one unit will 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 may be 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>
<term><varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname></term>
<listitem><para>Set the default overall block I/O weight for
the executed processes. Takes a single weight value (between
10 and 1000) to set the default block I/O weight. This controls
the <literal>blkio.weight</literal> control group attribute,
which defaults to 500. For details about this control group
attribute, see <ulink
url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.
The available I/O bandwidth is split up among all units within
one slice relative to their block I/O weight.</para>
<para>While <varname>StartupBlockIOWeight=</varname> only
applies to the startup phase of the system,
<varname>BlockIOWeight=</varname> applies to the later runtime
of the system, and if the former is not set also to the
startup phase. This allows prioritizing specific services at
boot-up differently than during runtime.</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 I/O 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 I/O 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>NetClass=</varname></term>
<listitem><para>Configures a network class number to assign to the
unit. This value will be set to the
<literal>net_cls.class_id</literal> property of the
<literal>net_cls</literal> cgroup of the unit. The directive
accepts a numerical value (for fixed number assignment) and the keyword
<literal>auto</literal> (for dynamic allocation). Network traffic of
all processes inside the unit will have the network class ID assigned
by the kernel. Also see
the kernel docs for
<ulink url="https://www.kernel.org/doc/Documentation/cgroups/net_cls.txt">net_cls controller</ulink>
and
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para></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>
<varlistentry>
<term><varname>Delegate=</varname></term>
<listitem>
<para>Turns on delegation of further resource control
partitioning to processes of the unit. For unprivileged
services (i.e. those using the <varname>User=</varname>
setting), this allows processes to create a subhierarchy
beneath its control group path. For privileged services and
scopes, this ensures the processes will have all control
group controllers enabled.</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>