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7 This file is part of systemd.
9 Copyright 2013 Zbigniew Jędrzejewski-Szmek
11 systemd is free software; you can redistribute it and/or modify it
12 under the terms of the GNU Lesser General Public License as published by
13 the Free Software Foundation; either version 2.1 of the License, or
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25 <refentry id="systemd.resource-control">
27 <title>systemd.resource-control</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>systemd.resource-control</refentrytitle>
42 <manvolnum>5</manvolnum>
46 <refname>systemd.resource-control</refname>
47 <refpurpose>Resource control unit settings</refpurpose>
52 <filename><replaceable>slice</replaceable>.slice</filename>,
53 <filename><replaceable>scope</replaceable>.scope</filename>,
54 <filename><replaceable>service</replaceable>.service</filename>,
55 <filename><replaceable>socket</replaceable>.socket</filename>,
56 <filename><replaceable>mount</replaceable>.mount</filename>,
57 <filename><replaceable>swap</replaceable>.swap</filename>
62 <title>Description</title>
64 <para>Unit configuration files for services, slices, scopes,
65 sockets, mount points, and swap devices share a subset of
66 configuration options for resource control of spawned
67 processes. Internally, this relies on the Control Groups
68 kernel concept for organizing processes in a hierarchial tree of
69 named groups for the purpose of resource management.</para>
71 <para>This man page lists the configuration options shared by
72 those six unit types. See
73 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
74 for the common options of all unit configuration files, and
75 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
76 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
77 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
78 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
79 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
81 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>
82 for more information on the specific unit configuration files. The
83 resource control configuration options are configured in the
84 [Slice], [Scope], [Service], [Socket], [Mount], or [Swap]
85 sections, depending on the unit type.</para>
88 url="http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/">New
89 Control Group Interfaces</ulink> for an introduction on how to make
90 use of resource control APIs from programs.</para>
94 <title>Options</title>
96 <para>Units of the types listed above can have settings
97 for resource control configuration:</para>
99 <variablelist class='unit-directives'>
102 <term><varname>CPUAccounting=</varname></term>
105 <para>Turn on CPU usage accounting for this unit. Takes a
106 boolean argument. Note that turning on CPU accounting for
107 one unit might also implicitly turn it on for all units
108 contained in the same slice and for all its parent slices
109 and the units contained therein. The system default for this
110 setting maybe controlled with
111 <varname>DefaultCPUAccounting=</varname> in
112 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
117 <term><varname>CPUShares=<replaceable>weight</replaceable></varname></term>
120 <para>Assign the specified CPU time share weight to the
121 processes executed. Takes an integer value. This controls
122 the <literal>cpu.shares</literal> control group attribute,
123 which defaults to 1024. For details about this control group
124 attribute, see <ulink
125 url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>
126 The available CPU time is split up among all units within a
127 slice relative to their CPU time share weight.</para>
129 <para>Implies <literal>CPUAccounting=true</literal>.</para>
134 <term><varname>CPUQuota=</varname></term>
137 <para>Assign the specified CPU time quota to the processes
138 executed. Takes a percentage value (suffixed with "%") or an
139 absolute time (suffixed by one of the common time units, us,
140 ms, s, ...). The percentage specifies how much CPU time the
141 unit shall get at maximum, relative to the total CPU time
142 available on one CPU. Use values > 100% for alloting CPU
143 time on more than one CPU. If an absolute time is specified
144 the processes of this unit will get this much absolute time
145 within each quota period, at maximum. This controls the
146 <literal>cpu.cfs_quota_us</literal> control group
147 attribute. For details about this control group attribute,
149 url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.</para>
151 <para>Example: <varname>CPUShares=20%</varname> ensures that
152 the executed processes will never get more than 20% CPU time
155 <para>Implies <literal>CPUAccounting=true</literal>.</para>
160 <term><varname>CPUQuotaPeriodSec=</varname></term>
163 <para>Specify the CPU quota period to use. Defaults to
164 100ms. This controls the <literal>cpu.cfs_period_us</literal>
165 control group attribute. For details about this control
166 group attribute, see <ulink
167 url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.</para>
169 <para>Implies <literal>CPUAccounting=true</literal>.</para>
174 <term><varname>StartupCPUShares=<replaceable>weight</replaceable></varname></term>
177 <para>Similar to <varname>CPUShares=</varname>. However,
178 only be assigned on startup state. After finishing startup, will be
179 re-assigned by <varname>CPUShares=</varname>. If
180 <varname>CPUShares=</varname> is not specified, then it will be
181 assigned to default(1024).</para>
186 <term><varname>MemoryAccounting=</varname></term>
189 <para>Turn on process and kernel memory accounting for this
190 unit. Takes a boolean argument. Note that turning on memory
191 accounting for one unit might also implicitly turn it on for
192 all its parent slices. The system default for this setting
193 maybe controlled with
194 <varname>DefaultMemoryAccounting=</varname> in
195 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
200 <term><varname>MemoryLimit=<replaceable>bytes</replaceable></varname></term>
203 <para>Specify the limit on maximum memory usage of the
204 executed processes. The limit specifies how much process and
205 kernel memory can be used by tasks in this unit. Takes a
206 memory size in bytes. If the value is suffixed with K, M, G
207 or T, the specified memory size is parsed as Kilobytes,
208 Megabytes, Gigabytes, or Terabytes (with the base 1024),
209 respectively. This controls the
210 <literal>memory.limit_in_bytes</literal> control group
211 attribute. For details about this control group attribute,
213 url="https://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>.</para>
215 <para>Implies <literal>MemoryAccounting=true</literal>.</para>
220 <term><varname>BlockIOAccounting=</varname></term>
223 <para>Turn on Block IO accounting for this unit. Takes a
224 boolean argument. Note that turning on block IO accounting
225 for one unit might also implicitly turn it on for all units
226 contained in the same slice and all for its parent slices
227 and the units contained therein. The system default for this
228 setting maybe controlled with
229 <varname>DefaultBlockIOAccounting=</varname> in
230 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
235 <term><varname>BlockIOWeight=<replaceable>weight</replaceable></varname></term>
237 <listitem><para>Set the default
238 overall block IO weight for the
239 executed processes. Takes a single
240 weight value (between 10 and 1000) to
241 set the default block IO weight. This
243 <literal>blkio.weight</literal>
244 control group attribute, which
245 defaults to 1000. For details about
246 this control group attribute, see
248 url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para>
251 <literal>BlockIOAccounting=true</literal>.</para>
256 <term><varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname></term>
259 <para>Similar to <varname>BlockIOWeight=</varname>. However,
260 only be assigned on startup state. After finishing startup, will be
261 re-assigned by <varname>BlockIOWeight=</varname>. If
262 <varname>BlockIOWeight=</varname> is not specified, then it will be
263 assigned to default(1000).</para>
268 <term><varname>BlockIODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term>
271 <para>Set the per-device overall block IO weight for the
272 executed processes. Takes a space-separated pair of a file
273 path and a weight value to specify the device specific
274 weight value, between 10 and 1000. (Example: "/dev/sda
275 500"). The file path may be specified as path to a block
276 device node or as any other file, in which case the backing
277 block device of the file system of the file is
278 determined. This controls the
279 <literal>blkio.weight_device</literal> control group
280 attribute, which defaults to 1000. Use this option multiple
281 times to set weights for multiple devices. For details about
282 this control group attribute, see <ulink
283 url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para>
286 <literal>BlockIOAccounting=true</literal>.</para>
291 <term><varname>BlockIOReadBandwidth=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term>
292 <term><varname>BlockIOWriteBandwidth=<replaceable>device</replaceable> <replaceable>bytes</replaceable></varname></term>
295 <para>Set the per-device overall block IO bandwidth limit
296 for the executed processes. Takes a space-separated pair of
297 a file path and a bandwidth value (in bytes per second) to
298 specify the device specific bandwidth. The file path may be
299 a path to a block device node, or as any other file in which
300 case the backing block device of the file system of the file
301 is used. If the bandwidth is suffixed with K, M, G, or T,
302 the specified bandwidth is parsed as Kilobytes, Megabytes,
303 Gigabytes, or Terabytes, respectively, to the base of
305 "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This
306 controls the <literal>blkio.read_bps_device</literal> and
307 <literal>blkio.write_bps_device</literal> control group
308 attributes. Use this option multiple times to set bandwidth
309 limits for multiple devices. For details about these control
310 group attributes, see <ulink
311 url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.
315 <literal>BlockIOAccounting=true</literal>.</para>
320 <term><varname>DeviceAllow=</varname></term>
323 <para>Control access to specific device nodes by the
324 executed processes. Takes two space-separated strings: a
325 device node specifier followed by a combination of
326 <constant>r</constant>, <constant>w</constant>,
327 <constant>m</constant> to control
328 <emphasis>r</emphasis>eading, <emphasis>w</emphasis>riting,
329 or creation of the specific device node(s) by the unit
330 (<emphasis>m</emphasis>knod), respectively. This controls
331 the <literal>devices.allow</literal> and
332 <literal>devices.deny</literal> control group
333 attributes. For details about these control group
334 attributes, see <ulink
335 url="https://www.kernel.org/doc/Documentation/cgroups/devices.txt">devices.txt</ulink>.</para>
337 <para>The device node specifier is either a path to a device
338 node in the file system, starting with
339 <filename>/dev/</filename>, or a string starting with either
340 <literal>char-</literal> or <literal>block-</literal>
341 followed by a device group name, as listed in
342 <filename>/proc/devices</filename>. The latter is useful to
343 whitelist all current and future devices belonging to a
344 specific device group at once. The device group is matched
345 according to file name globbing rules, you may hence use the
346 <literal>*</literal> and <literal>?</literal>
347 wildcards. Examples: <filename>/dev/sda5</filename> is a
348 path to a device node, referring to an ATA or SCSI block
349 device. <literal>char-pts</literal> and
350 <literal>char-alsa</literal> are specifiers for all pseudo
351 TTYs and all ALSA sound devices,
352 respectively. <literal>char-cpu/*</literal> is a specifier
353 matching all CPU related device groups.</para>
358 <term><varname>DevicePolicy=auto|closed|strict</varname></term>
362 Control the policy for allowing device access:
366 <term><option>strict</option></term>
368 <para>means to only allow types of access that are
369 explicitly specified.</para>
374 <term><option>closed</option></term>
376 <para>in addition, allows access to standard pseudo
378 <filename>/dev/null</filename>,
379 <filename>/dev/zero</filename>,
380 <filename>/dev/full</filename>,
381 <filename>/dev/random</filename>, and
382 <filename>/dev/urandom</filename>.
388 <term><option>auto</option></term>
391 in addition, allows access to all devices if no
392 explicit <varname>DeviceAllow=</varname> is present.
402 <term><varname>Slice=</varname></term>
405 <para>The name of the slice unit to place the unit
406 in. Defaults to <filename>system.slice</filename> for all
407 non-instantiated units of all unit types (except for slice
408 units themselves see below). Instance units are by default
409 placed in a subslice of <filename>system.slice</filename>
410 that is named after the template name.</para>
412 <para>This option may be used to arrange systemd units in a
413 hierarchy of slices each of which might have resource
414 settings applied.</para>
416 <para>For units of type slice, the only accepted value for
417 this setting is the parent slice. Since the name of a slice
418 unit implies the parent slice, it is hence redundant to ever
419 set this parameter directly for slice units.</para>
427 <title>See Also</title>
429 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
430 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
431 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
432 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
433 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
434 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
435 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
436 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
438 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
439 The documentation for control groups and specific controllers in the Linux kernel:
440 <ulink url="https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>,
441 <ulink url="https://www.kernel.org/doc/Documentation/cgroups/cpuacct.txt">cpuacct.txt</ulink>,
442 <ulink url="https://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>,
443 <ulink url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.