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SYSTEMD.RESOURCE-CONTROL(5)systemd.resource-controlSYSTEMD.RESOURCE-CONTROL(5)

NAME
systemd.resource-control - Resource control unit settings

SYNOPSIS
slice.slice, scope.scope, service.service, socket.socket, mount.mount,
swap.swap

DESCRIPTION
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.

This man page lists the configuration options shared by those six unit
types. See systemd.unit(5) for the common options of all unit
configuration files, and systemd.slice(5), systemd.scope(5),
systemd.service(5), systemd.socket(5), systemd.mount(5), and
systemd.swap(5) 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.

In addition, options which control resources available to programs
executed by systemd are listed in systemd.exec(5). Those options
complement options listed here.

See the New Control Group Interfaces[1] for an introduction on how to
make use of resource control APIs from programs.

IMPLICIT DEPENDENCIES
The following dependencies are implicitly added:

o Units with the Slice= setting set automatically acquire Requires=
and After= dependencies on the specified slice unit.

UNIFIED AND LEGACY CONTROL GROUP HIERARCHIES
The unified control group hierarchy is the new version of kernel
control group interface, see Control Groups v2[2]. 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.

CPU
CPUWeight= and StartupCPUWeight= replace CPUShares= and
StartupCPUShares=, respectively.

The "cpuacct" controller does not exist separately on the unified
hierarchy.

Memory
MemoryMax= replaces MemoryLimit=. MemoryLow= and MemoryHigh= are
effective only on unified hierarchy.

IO
"IO"-prefixed settings are a superset of and replace
"BlockIO"-prefixed ones. On unified hierarchy, IO resource control
also applies to buffered writes.

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.

Legacy control group hierarchy (see Control Groups version 1[3]), 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 the systemd user instance,
see systemd(1).

OPTIONS
Units of the types listed above can have settings for resource control
configuration:

CPUAccounting=
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
DefaultCPUAccounting= in systemd-system.conf(5).

CPUWeight=weight, StartupCPUWeight=weight
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 "cpu.weight" control
group attribute. The allowed range is 1 to 10000. Defaults to 100.
For details about this control group attribute, see Control Groups
v2[2] and CFS Scheduler[4]. The available CPU time is split up
among all units within one slice relative to their CPU time weight.

While StartupCPUWeight= only applies to the startup phase of the
system, CPUWeight= applies to normal runtime of the system, and if
the former is not set also to the startup phase. Using
StartupCPUWeight= allows prioritizing specific services at boot-up
differently than during normal runtime.

These settings replace CPUShares= and StartupCPUShares=.

CPUQuota=
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
"cpu.max" attribute on the unified control group hierarchy and
"cpu.cfs_quota_us" on legacy. For details about these control group
attributes, see Control Groups v2[2] and sched-bwc.txt[5].

Example: CPUQuota=20% ensures that the executed processes will
never get more than 20% CPU time on one CPU.

CPUQuotaPeriodSec=
Assign the duration over which the CPU time quota specified by
CPUQuota= is measured. Takes a time duration value in seconds, with
an optional suffix such as "ms" for milliseconds (or "s" for
seconds.) The default setting is 100ms. The period is clamped to
the range supported by the kernel, which is [1ms, 1000ms].
Additionally, the period is adjusted up so that the quota interval
is also at least 1ms. Setting CPUQuotaPeriodSec= to an empty value
resets it to the default.

This controls the second field of "cpu.max" attribute on the
unified control group hierarchy and "cpu.cfs_period_us" on legacy.
For details about these control group attributes, see Control
Groups v2[2] and CFS Scheduler[4].

Example: CPUQuotaPeriodSec=10ms to request that the CPU quota is
measured in periods of 10ms.

AllowedCPUs=
Restrict processes to be executed on specific CPUs. Takes a list of
CPU indices or ranges separated by either whitespace or commas. CPU
ranges are specified by the lower and upper CPU indices separated
by a dash.

Setting AllowedCPUs= doesn't guarantee that all of the CPUs will be
used by the processes as it may be limited by parent units. The
effective configuration is reported as EffectiveCPUs=.

This setting is supported only with the unified control group
hierarchy.

AllowedMemoryNodes=
Restrict processes to be executed on specific memory NUMA nodes.
Takes a list of memory NUMA nodes indices or ranges separated by
either whitespace or commas. Memory NUMA nodes ranges are specified
by the lower and upper CPU indices separated by a dash.

Setting AllowedMemoryNodes= doesn't guarantee that all of the
memory NUMA nodes will be used by the processes as it may be
limited by parent units. The effective configuration is reported as
EffectiveMemoryNodes=.

This setting is supported only with the unified control group
hierarchy.

MemoryAccounting=
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
DefaultMemoryAccounting= in systemd-system.conf(5).

MemoryMin=bytes
Specify the memory usage protection of the executed processes in
this unit. If the memory usages of this unit and all its ancestors
are below their minimum boundaries, this unit's memory won't be
reclaimed.

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 "infinity", all available memory is
protected, which may be useful in order to always inherit all of
the protection afforded by ancestors. This controls the
"memory.min" control group attribute. For details about this
control group attribute, see Memory Interface Files[6].

This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.

Units may have their children use a default "memory.min" value by
specifying DefaultMemoryMin=, which has the same semantics as
MemoryMin=. This setting does not affect "memory.min" in the unit
itself.

MemoryLow=bytes
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.

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 "infinity", all available memory is
protected, which may be useful in order to always inherit all of
the protection afforded by ancestors. This controls the
"memory.low" control group attribute. For details about this
control group attribute, see Memory Interface Files[6].

This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.

Units may have their children use a default "memory.low" value by
specifying DefaultMemoryLow=, which has the same semantics as
MemoryLow=. This setting does not affect "memory.low" in the unit
itself.

MemoryHigh=bytes
Specify the throttling 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.

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 "infinity", no memory throttling is
applied. This controls the "memory.high" control group attribute.
For details about this control group attribute, see Memory
Interface Files[6].

This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.

MemoryMax=bytes
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 MemoryHigh= as the main control mechanism and
use MemoryMax= as the last line of defense.

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 "infinity", no memory limit is applied.
This controls the "memory.max" control group attribute. For details
about this control group attribute, see Memory Interface Files[6].

This setting replaces MemoryLimit=.

MemorySwapMax=bytes
Specify the absolute limit on swap usage of the executed processes
in this unit.

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 "infinity", no swap limit is applied.
This controls the "memory.swap.max" control group attribute. For
details about this control group attribute, see Memory Interface
Files[6].

This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.

TasksAccounting=
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
DefaultTasksAccounting= in systemd-system.conf(5).

TasksMax=N
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 "infinity", no tasks limit is
applied. This controls the "pids.max" control group attribute. For
details about this control group attribute, see Process Number
Controller[7].

The system default for this setting may be controlled with
DefaultTasksMax= in systemd-system.conf(5).

IOAccounting=
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
DefaultIOAccounting= in systemd-system.conf(5).

This setting replaces BlockIOAccounting= and disables settings
prefixed with BlockIO or StartupBlockIO.

IOWeight=weight, StartupIOWeight=weight
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 "io.weight" control
group attribute, which defaults to 100. For details about this
control group attribute, see IO Interface Files[8]. The available
I/O bandwidth is split up among all units within one slice relative
to their block I/O weight.

While StartupIOWeight= only applies to the startup phase of the
system, IOWeight= 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.

These settings replace BlockIOWeight= and StartupBlockIOWeight= and
disable settings prefixed with BlockIO or StartupBlockIO.

IODeviceWeight=device weight
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 "io.weight" 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 IO Interface Files[8].

This setting replaces BlockIODeviceWeight= and disables settings
prefixed with BlockIO or StartupBlockIO.

The specified device node should reference a block device that has
an I/O scheduler associated, i.e. should not refer to partition or
loopback block devices, but to the originating, physical device.
When a path to a regular file or directory is specified it is
attempted to discover the correct originating device backing the
file system of the specified path. This works correctly only for
simpler cases, where the file system is directly placed on a
partition or physical block device, or where simple 1:1 encryption
using dm-crypt/LUKS is used. This discovery does not cover complex
storage and in particular RAID and volume management storage
devices.

IOReadBandwidthMax=device bytes, IOWriteBandwidthMax=device bytes
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 "io.max" control group attributes. Use this option
multiple times to set bandwidth limits for multiple devices. For
details about this control group attribute, see IO Interface
Files[8].

These settings replace BlockIOReadBandwidth= and
BlockIOWriteBandwidth= and disable settings prefixed with BlockIO
or StartupBlockIO.

Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.

IOReadIOPSMax=device IOPS, IOWriteIOPSMax=device IOPS
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 "io.max" control group attributes. Use this option
multiple times to set IOPS limits for multiple devices. For details
about this control group attribute, see IO Interface Files[8].

These settings are supported only if the unified control group
hierarchy is used and disable settings prefixed with BlockIO or
StartupBlockIO.

Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.

IODeviceLatencyTargetSec=device target
Set the per-device average target I/O latency for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a file path and a timespan separated by a space to
specify the device specific latency target. (Example: "/dev/sda
25ms"). 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
"io.latency" control group attribute. Use this option multiple
times to set latency target for multiple devices. For details about
this control group attribute, see IO Interface Files[8].

Implies "IOAccounting=yes".

These settings are supported only if the unified control group
hierarchy is used.

Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.

IPAccounting=
Takes a boolean argument. If true, turns on IPv4 and IPv6 network
traffic accounting for packets sent or received by the unit. When
this option is turned on, all IPv4 and IPv6 sockets created by any
process of the unit are accounted for.

When this option is used in socket units, it applies to all IPv4
and IPv6 sockets associated with it (including both listening and
connection sockets where this applies). Note that for
socket-activated services, this configuration setting and the
accounting data of the service unit and the socket unit are kept
separate, and displayed separately. No propagation of the setting
and the collected statistics is done, in either direction.
Moreover, any traffic sent or received on any of the socket unit's
sockets is accounted to the socket unit -- and never to the service
unit it might have activated, even if the socket is used by it.

The system default for this setting may be controlled with
DefaultIPAccounting= in systemd-system.conf(5).

IPAddressAllow=ADDRESS[/PREFIXLENGTH]...,
IPAddressDeny=ADDRESS[/PREFIXLENGTH]...
Turn on address range network traffic filtering for IP packets sent
and received over AF_INET and AF_INET6 sockets. Both directives
take a space separated list of IPv4 or IPv6 addresses, each
optionally suffixed with an address prefix length in bits
(separated by a "/" character). If the latter is omitted, the
address is considered a host address, i.e. the prefix covers the
whole address (32 for IPv4, 128 for IPv6).

The access lists configured with this option are applied to all
sockets created by processes of this unit (or in the case of socket
units, associated with it). The lists are implicitly combined with
any lists configured for any of the parent slice units this unit
might be a member of. By default all access lists are empty. Both
ingress and egress traffic is filtered by these settings. In case
of ingress traffic the source IP address is checked against these
access lists, in case of egress traffic the destination IP address
is checked. When configured the lists are enforced as follows:

o Access will be granted in case an IP packet's
destination/source address matches any entry in the
IPAddressAllow= setting.

o Otherwise, access will be denied in case its destination/source
address matches any entry in the IPAddressDeny= setting.

o Otherwise, access will be granted.

In order to implement a whitelisting IP firewall, it is recommended
to use a IPAddressDeny=any setting on an upper-level slice unit
(such as the root slice -.slice or the slice containing all system
services system.slice - see systemd.special(7) for details on these
slice units), plus individual per-service IPAddressAllow= lines
permitting network access to relevant services, and only them.

Note that for socket-activated services, the IP access list
configured on the socket unit applies to all sockets associated
with it directly, but not to any sockets created by the ultimately
activated services for it. Conversely, the IP access list
configured for the service is not applied to any sockets passed
into the service via socket activation. Thus, it is usually a good
idea, to replicate the IP access lists on both the socket and the
service unit, however it often makes sense to maintain one list
more open and the other one more restricted, depending on the
usecase.

If these settings are used multiple times in the same unit the
specified lists are combined. If an empty string is assigned to
these settings the specific access list is reset and all previous
settings undone.

In place of explicit IPv4 or IPv6 address and prefix length
specifications a small set of symbolic names may be used. The
following names are defined:

Table 1. Special address/network names
+--------------+---------------------+---------------------+
|Symbolic Name | Definition | Meaning |
+--------------+---------------------+---------------------+
|any | 0.0.0.0/0 ::/0 | Any host |
+--------------+---------------------+---------------------+
|localhost | 127.0.0.0/8 ::1/128 | All addresses on |
| | | the local loopback |
+--------------+---------------------+---------------------+
|link-local | 169.254.0.0/16 | All link-local IP |
| | fe80::/64 | addresses |
+--------------+---------------------+---------------------+
|multicast | 224.0.0.0/4 | All IP multicasting |
| | ff00::/8 | addresses |
+--------------+---------------------+---------------------+
Note that these settings might not be supported on some systems
(for example if eBPF control group support is not enabled in the
underlying kernel or container manager). These settings will have
no effect in that case. If compatibility with such systems is
desired it is hence recommended to not exclusively rely on them for
IP security.

IPIngressFilterPath=BPF_FS_PROGRAMM_PATH,
IPEgressFilterPath=BPF_FS_PROGRAMM_PATH
Add custom network traffic filters implemented as BPF programs,
applying to all IP packets sent and received over AF_INET and
AF_INET6 sockets. Takes an absolute path to a pinned BPF program in
the BPF virtual filesystem (/sys/fs/bpf/).

The filters configured with this option are applied to all sockets
created by processes of this unit (or in the case of socket units,
associated with it). The filters are loaded in addition to filters
any of the parent slice units this unit might be a member of as
well as any IPAddressAllow= and IPAddressDeny= filters in any of
these units. By default there are no filters specified.

If these settings are used multiple times in the same unit all the
specified programs are attached. If an empty string is assigned to
these settings the program list is reset and all previous specified
programs ignored.

Note that for socket-activated services, the IP filter programs
configured on the socket unit apply to all sockets associated with
it directly, but not to any sockets created by the ultimately
activated services for it. Conversely, the IP filter programs
configured for the service are not applied to any sockets passed
into the service via socket activation. Thus, it is usually a good
idea, to replicate the IP filter programs on both the socket and
the service unit, however it often makes sense to maintain one
configuration more open and the other one more restricted,
depending on the usecase.

Note that these settings might not be supported on some systems
(for example if eBPF control group support is not enabled in the
underlying kernel or container manager). These settings will fail
the service in that case. If compatibility with such systems is
desired it is hence recommended to attach your filter manually
(requires Delegate=yes) instead of using this setting.

DeviceAllow=
Control access to specific device nodes by the executed processes.
Takes two space-separated strings: a device node specifier followed
by a combination of r, w, m to control reading, writing, or
creation of the specific device node(s) by the unit (mknod),
respectively. On cgroup-v1 this controls the "devices.allow"
control group attribute. For details about this control group
attribute, see Device Whitelist Controller[9]. In the unified
cgroup hierarchy this functionality is implemented using eBPF
filtering.

The device node specifier is either a path to a device node in the
file system, starting with /dev/, or a string starting with either
"char-" or "block-" followed by a device group name, as listed in
/proc/devices. 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 filename globbing rules, you
may hence use the "*" and "?" wildcards. (Note that such globbing
wildcards are not available for device node path specifications!)
In order to match device nodes by numeric major/minor, use device
node paths in the /dev/char/ and /dev/block/ directories. However,
matching devices by major/minor is generally not recommended as
assignments are neither stable nor portable between systems or
different kernel versions.

Examples: /dev/sda5 is a path to a device node, referring to an ATA
or SCSI block device. "char-pts" and "char-alsa" are specifiers
for all pseudo TTYs and all ALSA sound devices, respectively.
"char-cpu/*" is a specifier matching all CPU related device groups.

Note that whitelists defined this way should only reference device
groups which are resolvable at the time the unit is started. Any
device groups not resolvable then are not added to the device
whitelist. In order to work around this limitation, consider
extending service units with a pair of After=modprobe@xyz.service
and Wants=modprobe@xyz.service lines that load the necessary kernel
module implementing the device group if missing. Example:

...
[Unit]
Wants=modprobe@loop.service
After=modprobe@loop.service

[Service]
DeviceAllow=block-loop
DeviceAllow=/dev/loop-control
...

DevicePolicy=auto|closed|strict
Control the policy for allowing device access:

strict
means to only allow types of access that are explicitly
specified.

closed
in addition, allows access to standard pseudo devices including
/dev/null, /dev/zero, /dev/full, /dev/random, and /dev/urandom.

auto
in addition, allows access to all devices if no explicit
DeviceAllow= is present. This is the default.

Slice=
The name of the slice unit to place the unit in. Defaults to
system.slice 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 system.slice that is named after
the template name.

This option may be used to arrange systemd units in a hierarchy of
slices each of which might have resource settings applied.

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.

Special care should be taken when relying on the default slice
assignment in templated service units that have
DefaultDependencies=no set, see systemd.service(5), section
"Default Dependencies" for details.

Delegate=
Turns on delegation of further resource control partitioning to
processes of the unit. Units where this is enabled may create and
manage their own private subhierarchy of control groups below the
control group of the unit itself. For unprivileged services (i.e.
those using the User= setting) the unit's control group will be
made accessible to the relevant user. When enabled the service
manager will refrain from manipulating control groups or moving
processes below the unit's control group, so that a clear concept
of ownership is established: the control group tree above the
unit's control group (i.e. towards the root control group) is owned
and managed by the service manager of the host, while the control
group tree below the unit's control group is owned and managed by
the unit itself. Takes either a boolean argument or a list of
control group controller names. If true, delegation is turned on,
and all supported controllers are enabled for the unit, making them
available to the unit's processes for management. If false,
delegation is turned off entirely (and no additional controllers
are enabled). If set to a list of controllers, delegation is turned
on, and the specified controllers are enabled for the unit. Note
that additional controllers than the ones specified might be made
available as well, depending on configuration of the containing
slice unit or other units contained in it. Note that assigning the
empty string will enable delegation, but reset the list of
controllers, all assignments prior to this will have no effect.
Defaults to false.

Note that controller delegation to less privileged code is only
safe on the unified control group hierarchy. Accordingly, access to
the specified controllers will not be granted to unprivileged
services on the legacy hierarchy, even when requested.

The following controller names may be specified: cpu, cpuacct,
cpuset, io, blkio, memory, devices, pids, bpf-firewall, and
bpf-devices.

Not all of these controllers are available on all kernels however,
and some are specific to the unified hierarchy while others are
specific to the legacy hierarchy. Also note that the kernel might
support further controllers, which aren't covered here yet as
delegation is either not supported at all for them or not defined
cleanly.

For further details on the delegation model consult Control Group
APIs and Delegation[10].

DisableControllers=
Disables controllers from being enabled for a unit's children. If a
controller listed is already in use in its subtree, the controller
will be removed from the subtree. This can be used to avoid child
units being able to implicitly or explicitly enable a controller.
Defaults to not disabling any controllers.

It may not be possible to successfully disable a controller if the
unit or any child of the unit in question delegates controllers to
its children, as any delegated subtree of the cgroup hierarchy is
unmanaged by systemd.

Multiple controllers may be specified, separated by spaces. You may
also pass DisableControllers= multiple times, in which case each
new instance adds another controller to disable. Passing
DisableControllers= by itself with no controller name present
resets the disabled controller list.

The following controller names may be specified: cpu, cpuacct,
cpuset, io, blkio, memory, devices, pids, bpf-firewall, and
bpf-devices.

DEPRECATED OPTIONS
The following options are deprecated. Use the indicated superseding
options instead:

CPUShares=weight, StartupCPUShares=weight
Assign the specified CPU time share weight to the processes
executed. These options take an integer value and control the
"cpu.shares" control group attribute. The allowed range is 2 to
262144. Defaults to 1024. For details about this control group
attribute, see CFS Scheduler[4]. The available CPU time is split up
among all units within one slice relative to their CPU time share
weight.

While StartupCPUShares= only applies to the startup phase of the
system, CPUShares= applies to normal runtime of the system, and if
the former is not set also to the startup phase. Using
StartupCPUShares= allows prioritizing specific services at boot-up
differently than during normal runtime.

Implies "CPUAccounting=yes".

These settings are deprecated. Use CPUWeight= and StartupCPUWeight=
instead.

MemoryLimit=bytes
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 "infinity", no
memory limit is applied. This controls the "memory.limit_in_bytes"
control group attribute. For details about this control group
attribute, see Memory Resource Controller[11].

Implies "MemoryAccounting=yes".

This setting is deprecated. Use MemoryMax= instead.

BlockIOAccounting=
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
DefaultBlockIOAccounting= in systemd-system.conf(5).

This setting is deprecated. Use IOAccounting= instead.

BlockIOWeight=weight, StartupBlockIOWeight=weight
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 "blkio.weight"
control group attribute, which defaults to 500. For details about
this control group attribute, see Block IO Controller[12]. The
available I/O bandwidth is split up among all units within one
slice relative to their block I/O weight.

While StartupBlockIOWeight= only applies to the startup phase of
the system, BlockIOWeight= 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.

Implies "BlockIOAccounting=yes".

These settings are deprecated. Use IOWeight= and StartupIOWeight=
instead.

BlockIODeviceWeight=device weight
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 "blkio.weight_device" 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 Block IO Controller[12].

Implies "BlockIOAccounting=yes".

This setting is deprecated. Use IODeviceWeight= instead.

BlockIOReadBandwidth=device bytes, BlockIOWriteBandwidth=device bytes
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 "blkio.throttle.read_bps_device" and
"blkio.throttle.write_bps_device" control group attributes. Use
this option multiple times to set bandwidth limits for multiple
devices. For details about these control group attributes, see
Block IO Controller[12].

Implies "BlockIOAccounting=yes".

These settings are deprecated. Use IOReadBandwidthMax= and
IOWriteBandwidthMax= instead.

SEE ALSO
systemd(1), systemd-system.conf(5), systemd.unit(5),
systemd.service(5), systemd.slice(5), systemd.scope(5),
systemd.socket(5), systemd.mount(5), systemd.swap(5), systemd.exec(5),
systemd.directives(7), systemd.special(7), The documentation for
control groups and specific controllers in the Linux kernel: Control
Groups v2[2].

NOTES
1. New Control Group Interfaces
https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/

2. Control Groups v2
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html

3. Control Groups version 1
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/

4. CFS Scheduler
https://www.kernel.org/doc/html/latest/scheduler/sched-design-CFS.html

5. sched-bwc.txt
https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt

6. Memory Interface Files
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files

7. Process Number Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/pids.html

8. IO Interface Files
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#io-interface-files

9. Device Whitelist Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/devices.html

10. Control Group APIs and Delegation
https://systemd.io/CGROUP_DELEGATION

11. Memory Resource Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/memory.html

12. Block IO Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/blkio-controller.html

systemd 245 SYSTEMD.RESOURCE-CONTROL(5)