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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 Linux Control |
| Groups (cgroups) 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>In addition, options which control resources available to programs |
| <emphasis>executed</emphasis> by systemd are listed in |
| <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
| Those options complement options listed here.</para> |
| |
| <para>See the <ulink |
| url="https://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 automatically acquire <varname>Requires=</varname> and |
| <varname>After=</varname> dependencies on the specified slice unit.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Unified and Legacy Control Group Hierarchies</title> |
| |
| <para>The unified control group hierarchy is the new version of kernel control group interface, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>. Depending on the resource type, |
| there are differences in resource control capabilities. Also, because of interface changes, some resource types |
| have separate set of options on the unified hierarchy.</para> |
| |
| <para> |
| <variablelist> |
| |
| <varlistentry> |
| <term><option>CPU</option></term> |
| <listitem> |
| <para>Due to the lack of consensus in the kernel community, the CPU controller support on the unified |
| control group hierarchy requires out-of-tree kernel patches. See <ulink |
| url="https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/tree/Documentation/cgroup-v2-cpu.txt?h=cgroup-v2-cpu">cgroup-v2-cpu.txt</ulink>.</para> |
| |
| <para><varname>CPUWeight=</varname> and <varname>StartupCPUWeight=</varname> replace |
| <varname>CPUShares=</varname> and <varname>StartupCPUShares=</varname>, respectively.</para> |
| |
| <para>The <literal>cpuacct</literal> controller does not exist separately on the unified hierarchy.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>Memory</option></term> |
| <listitem> |
| <para><varname>MemoryMax=</varname> replaces <varname>MemoryLimit=</varname>. <varname>MemoryLow=</varname> |
| and <varname>MemoryHigh=</varname> are effective only on unified hierarchy.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>IO</option></term> |
| <listitem> |
| <para><varname>IO</varname> prefixed settings are superset of and replace <varname>BlockIO</varname> |
| prefixed ones. On unified hierarchy, IO resource control also applies to buffered writes.</para> |
| </listitem> |
| </varlistentry> |
| |
| </variablelist> |
| </para> |
| |
| <para>To ease the transition, there is best-effort translation between the two versions of settings. For each |
| controller, if any of the settings for the unified hierarchy are present, all settings for the legacy hierarchy are |
| ignored. If the resulting settings are for the other type of hierarchy, the configurations are translated before |
| application.</para> |
| |
| <para>Legacy control group hierarchy (see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt">cgroups.txt</ulink>), also called cgroup-v1, |
| doesn't allow safe delegation of controllers to unprivileged processes. If the system uses the legacy control group |
| hierarchy, resource control is disabled for systemd user instance, see |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. |
| </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>CPUWeight=<replaceable>weight</replaceable></varname></term> |
| <term><varname>StartupCPUWeight=<replaceable>weight</replaceable></varname></term> |
| |
| <listitem> |
| <para>Assign the specified CPU time weight to the processes executed, if the unified control group hierarchy |
| is used on the system. These options take an integer value and control the <literal>cpu.weight</literal> |
| control group attribute. The allowed range is 1 to 10000. Defaults to 100. For details about this control |
| group attribute, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink> and <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 weight.</para> |
| |
| <para>While <varname>StartupCPUWeight=</varname> only applies to the startup phase of the system, |
| <varname>CPUWeight=</varname> applies to normal runtime of the system, and if the former is not set also to |
| the startup phase. Using <varname>StartupCPUWeight=</varname> allows prioritizing specific services at |
| boot-up differently than during normal runtime.</para> |
| |
| <para>Implies <literal>CPUAccounting=true</literal>.</para> |
| |
| <para>These settings replace <varname>CPUShares=</varname> and <varname>StartupCPUShares=</varname>.</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 > 100% for allotting CPU time on more than one CPU. This controls the |
| <literal>cpu.max</literal> attribute on the unified control group hierarchy and |
| <literal>cpu.cfs_quota_us</literal> on legacy. For details about these control group attributes, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink> and <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>MemoryLow=<replaceable>bytes</replaceable></varname></term> |
| |
| <listitem> |
| <para>Specify the best-effort memory usage protection of the executed processes in this unit. If the memory |
| usages of this unit and all its ancestors are below their low boundaries, this unit's memory won't be |
| reclaimed as long as memory can be reclaimed from unprotected units.</para> |
| |
| <para>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. Alternatively, a |
| percentage value may be specified, which is taken relative to the installed physical memory on the |
| system. This controls the <literal>memory.low</literal> control group attribute. For details about this |
| control group attribute, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para> |
| |
| <para>Implies <literal>MemoryAccounting=true</literal>.</para> |
| |
| <para>This setting is supported only if the unified control group hierarchy is used and disables |
| <varname>MemoryLimit=</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>MemoryHigh=<replaceable>bytes</replaceable></varname></term> |
| |
| <listitem> |
| <para>Specify the high limit on memory usage of the executed processes in this unit. Memory usage may go |
| above the limit if unavoidable, but the processes are heavily slowed down and memory is taken away |
| aggressively in such cases. This is the main mechanism to control memory usage of a unit.</para> |
| |
| <para>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. Alternatively, a |
| percentage value may be specified, which is taken relative to the installed physical memory on the |
| system. If assigned the |
| special value <literal>infinity</literal>, no memory limit is applied. This controls the |
| <literal>memory.high</literal> control group attribute. For details about this control group attribute, see |
| <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para> |
| |
| <para>Implies <literal>MemoryAccounting=true</literal>.</para> |
| |
| <para>This setting is supported only if the unified control group hierarchy is used and disables |
| <varname>MemoryLimit=</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>MemoryMax=<replaceable>bytes</replaceable></varname></term> |
| |
| <listitem> |
| <para>Specify the absolute limit on memory usage of the executed processes in this unit. If memory usage |
| cannot be contained under the limit, out-of-memory killer is invoked inside the unit. It is recommended to |
| use <varname>MemoryHigh=</varname> as the main control mechanism and use <varname>MemoryMax=</varname> as the |
| last line of defense.</para> |
| |
| <para>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. Alternatively, a |
| percentage value may be specified, which is taken relative to the installed physical memory on the system. If |
| assigned the special value <literal>infinity</literal>, no memory limit is applied. This controls the |
| <literal>memory.max</literal> control group attribute. For details about this control group attribute, see |
| <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para> |
| |
| <para>Implies <literal>MemoryAccounting=true</literal>.</para> |
| |
| <para>This setting replaces <varname>MemoryLimit=</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>MemorySwapMax=<replaceable>bytes</replaceable></varname></term> |
| |
| <listitem> |
| <para>Specify the absolute limit on swap usage of the executed processes in this unit.</para> |
| |
| <para>Takes a swap size in bytes. If the value is suffixed with K, M, G or T, the specified swap size is |
| parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. If assigned the |
| special value <literal>infinity</literal>, no swap limit is applied. This controls the |
| <literal>memory.swap.max</literal> control group attribute. For details about this control group attribute, |
| see <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para> |
| |
| <para>Implies <literal>MemoryAccounting=true</literal>.</para> |
| |
| <para>This setting is supported only if the unified control group hierarchy is used and disables |
| <varname>MemoryLimit=</varname>.</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. This either takes an absolute number |
| of tasks or a percentage value that is taken relative to the configured maximum number of tasks on the |
| system. 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/cgroup-v1/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>IOAccounting=</varname></term> |
| |
| <listitem> |
| <para>Turn on Block I/O accounting for this unit, if the unified control group hierarchy is used on the |
| system. 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>DefaultIOAccounting=</varname> |
| in |
| <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> |
| |
| <para>This setting replaces <varname>BlockIOAccounting=</varname> and disables settings prefixed with |
| <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>IOWeight=<replaceable>weight</replaceable></varname></term> |
| <term><varname>StartupIOWeight=<replaceable>weight</replaceable></varname></term> |
| |
| <listitem> |
| <para>Set the default overall block I/O weight for the executed processes, if the unified control group |
| hierarchy is used on the system. Takes a single weight value (between 1 and 10000) to set the default block |
| I/O weight. This controls the <literal>io.weight</literal> control group attribute, which defaults to |
| 100. For details about this control group attribute, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.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>StartupIOWeight=</varname> only applies |
| to the startup phase of the system, |
| <varname>IOWeight=</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>IOAccounting=true</literal>.</para> |
| |
| <para>These settings replace <varname>BlockIOWeight=</varname> and <varname>StartupBlockIOWeight=</varname> |
| and disable settings prefixed with <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>IODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term> |
| |
| <listitem> |
| <para>Set the per-device overall block I/O weight for the executed processes, if the unified control group |
| hierarchy is used on the system. Takes a space-separated pair of a file path and a weight value to specify |
| the device specific weight value, between 1 and 10000. (Example: "/dev/sda 1000"). 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>io.weight</literal> control group |
| attribute, which defaults to 100. 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/cgroup-v2.txt">cgroup-v2.txt</ulink>.</para> |
| |
| <para>Implies <literal>IOAccounting=true</literal>.</para> |
| |
| <para>This setting replaces <varname>BlockIODeviceWeight=</varname> and disables settings prefixed with |
| <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>IOReadBandwidthMax=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term> |
| <term><varname>IOWriteBandwidthMax=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term> |
| |
| <listitem> |
| <para>Set the per-device overall block I/O bandwidth maximum limit for the executed processes, if the unified |
| control group hierarchy is used on the system. This limit is not work-conserving and the executed processes |
| are not allowed to use more even if the device has idle capacity. 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>io.max</literal> control |
| group attributes. Use this option multiple times to set bandwidth limits for multiple devices. For details |
| about this control group attribute, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>. |
| </para> |
| |
| <para>Implies <literal>IOAccounting=true</literal>.</para> |
| |
| <para>These settings replace <varname>BlockIOReadBandwidth=</varname> and |
| <varname>BlockIOWriteBandwidth=</varname> and disable settings prefixed with <varname>BlockIO</varname> or |
| <varname>StartupBlockIO</varname>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>IOReadIOPSMax=<replaceable>device</replaceable> <replaceable>IOPS</replaceable></varname></term> |
| <term><varname>IOWriteIOPSMax=<replaceable>device</replaceable> <replaceable>IOPS</replaceable></varname></term> |
| |
| <listitem> |
| <para>Set the per-device overall block I/O IOs-Per-Second maximum limit for the executed processes, if the |
| unified control group hierarchy is used on the system. This limit is not work-conserving and the executed |
| processes are not allowed to use more even if the device has idle capacity. Takes a space-separated pair of |
| a file path and an IOPS value to specify the device specific IOPS. 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 IOPS is suffixed with K, M, G, or T, the specified IOPS is parsed as KiloIOPS, MegaIOPS, |
| GigaIOPS, or TeraIOPS, respectively, to the base of 1000. (Example: |
| "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 1K"). This controls the <literal>io.max</literal> control |
| group attributes. Use this option multiple times to set IOPS limits for multiple devices. For details about |
| this control group attribute, see <ulink |
| url="https://www.kernel.org/doc/Documentation/cgroup-v2.txt">cgroup-v2.txt</ulink>. |
| </para> |
| |
| <para>Implies <literal>IOAccounting=true</literal>.</para> |
| |
| <para>These settings are supported only if the unified control group hierarchy is used and disable settings |
| prefixed with <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</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/cgroup-v1/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> |
| |
| <para>Special care should be taken when relying on the default slice assignment in templated service units |
| that have <varname>DefaultDependencies=no</varname> set, see |
| <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, section |
| "Automatic Dependencies" for details.</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>Deprecated Options</title> |
| |
| <para>The following options are deprecated. Use the indicated superseding options instead:</para> |
| |
| <variablelist class='unit-directives'> |
| |
| <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>Implies <literal>CPUAccounting=true</literal>.</para> |
| |
| <para>These settings are deprecated. Use <varname>CPUWeight=</varname> and |
| <varname>StartupCPUWeight=</varname> instead.</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. Alternatively, a percentage value may be specified, which is |
| taken relative to the installed physical memory on the system. 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/cgroup-v1/memory.txt">memory.txt</ulink>.</para> |
| |
| <para>Implies <literal>MemoryAccounting=true</literal>.</para> |
| |
| <para>This setting is deprecated. Use <varname>MemoryMax=</varname> instead.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>BlockIOAccounting=</varname></term> |
| |
| <listitem> |
| <para>Turn on Block I/O accounting for this unit, if the legacy control group hierarchy is used on the |
| system. 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> |
| |
| <para>This setting is deprecated. Use <varname>IOAccounting=</varname> instead.</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, if the legacy control |
| group hierarchy is used on the system. 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/cgroup-v1/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> |
| |
| <para>These settings are deprecated. Use <varname>IOWeight=</varname> and <varname>StartupIOWeight=</varname> |
| instead.</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, if the legacy control group |
| hierarchy is used on the system. 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/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>.</para> |
| |
| <para>Implies |
| <literal>BlockIOAccounting=true</literal>.</para> |
| |
| <para>This setting is deprecated. Use <varname>IODeviceWeight=</varname> instead.</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, if the legacy control |
| group hierarchy is used on the system. 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.throttle.read_bps_device</literal> and <literal>blkio.throttle.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/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>. |
| </para> |
| |
| <para>Implies |
| <literal>BlockIOAccounting=true</literal>.</para> |
| |
| <para>These settings are deprecated. Use <varname>IOReadBandwidthMax=</varname> and |
| <varname>IOWriteBandwidthMax=</varname> instead.</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.exec</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/cgroup-v1/cgroups.txt">cgroups.txt</ulink>, |
| <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/cpuacct.txt">cpuacct.txt</ulink>, |
| <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt">memory.txt</ulink>, |
| <ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/blkio-controller.txt">blkio-controller.txt</ulink>. |
| </para> |
| </refsect1> |
| </refentry> |