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NAME | SYNOPSIS | DESCRIPTION | IMPLICIT DEPENDENCIES | UNIFIED AND LEGACY CONTROL GROUP HIERARCHIES | OPTIONS | DEPRECATED OPTIONS | SEE ALSO | NOTES | COLOPHON |
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SYSTEMD.RESOURCE-CONTROL(5)temd.resource-controlTEMD.RESOURCE-CONTROL(5)
systemd.resource-control - Resource control unit settings
slice.slice, scope.scope, service.service, socket.socket,
mount.mount, swap.swap
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.
The following dependencies are implicitly added:
• Units with the Slice= setting set automatically acquire
Requires= and After= dependencies on the specified slice
unit.
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).
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, MemoryLow=bytes
Specify the memory usage protection of the executed processes
in this unit. When reclaiming memory, the unit is treated as
if it was using less memory resulting in memory to be
preferentially reclaimed from unprotected units. Using
MemoryLow= results in a weaker protection where memory may
still be reclaimed to avoid invoking the OOM killer in case
there is no other reclaimable memory.
For a protection to be effective, it is generally required to
set a corresponding allocation on all ancestors, which is
then distributed between children (with the exception of the
root slice). Any MemoryMin= or MemoryLow= allocation that is
not explicitly distributed to specific children is used to
create a shared protection for all children. As this is a
shared protection, the children will freely compete for the
memory.
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" or
"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.min" or
"memory.low" value by specifying DefaultMemoryMin= or
DefaultMemoryLow=, which has the same semantics as MemoryMin=
and MemoryLow=. This setting does not affect "memory.min" or
"memory.low" in the unit itself. Using it to set a default
child allocation is only useful on kernels older than 5.7,
which do not support the "memory_recursiveprot" cgroup2 mount
option.
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 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
after a "/" character. If the suffix is omitted, the address
is considered a host address, i.e. the filter covers the
whole address (32 bits for IPv4, 128 bits 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
both 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.
The following rules are applied in turn:
• Access is granted when the checked IP address matches an
entry in the IPAddressAllow= list.
• Otherwise, access is denied when the checked IP address
matches an entry in the IPAddressDeny= list.
• Otherwise, access is granted.
In order to implement an allow-listing 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. Nevertheless,
it may make 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 │ All addresses on │
│ │ ::1/128 │ 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 │
│ │ ff00::/8 │ multicasting │
│ │ │ 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_PROGRAM_PATH,
IPEgressFilterPath=BPF_FS_PROGRAM_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
allow-list 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 allow lists 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 allow list. 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.
ManagedOOMSwap=auto|kill, ManagedOOMMemoryPressure=auto|kill
Specifies how systemd-oomd.service(8) will act on this unit's
cgroups. Defaults to auto.
When set to kill, systemd-oomd will actively monitor this
unit's cgroup metrics to decide whether it needs to act. If
the cgroup passes the limits set by oomd.conf(5) or its
overrides, systemd-oomd will send a SIGKILL to all of the
processes under the chosen candidate cgroup. Note that only
descendant cgroups can be eligible candidates for killing;
the unit that set its property to kill is not a candidate
(unless one of its ancestors set their property to kill). You
can find more details on candidates and kill behavior at
systemd-oomd.service(8) and oomd.conf(5). Setting either of
these properties to kill will also automatically acquire
After= and Wants= dependencies on systemd-oomd.service unless
DefaultDependencies=no.
When set to auto, systemd-oomd will not actively use this
cgroup's data for monitoring and detection. However, if an
ancestor cgroup has one of these properties set to kill, a
unit with auto can still be an eligible candidate for
systemd-oomd to act on.
ManagedOOMMemoryPressureLimitPercent=
Overrides the default memory pressure limit set by
oomd.conf(5) for this unit (cgroup). Takes a percentage value
between 0% and 100%, inclusive. This property is ignored
unless ManagedOOMMemoryPressure=kill. Defaults to 0%, which
means use the default set by oomd.conf(5).
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.
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),
systemd-oomd.service(8), The documentation for control groups and
specific controllers in the Linux kernel: Control Groups v2[2].
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
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-12-18. (At that
time, the date of the most recent commit that was found in the
repository was 2020-12-18.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 247 SYSTEMD.RESOURCE-CONTROL(5)
Pages that refer to this page: homectl(1), systemctl(1), systemd-cgtop(1), systemd-run(1), oomd.conf(5), org.freedesktop.systemd1(5), systemd.exec(5), systemd.mount(5), systemd.scope(5), systemd.service(5), systemd.slice(5), systemd.socket(5), systemd.swap(5), systemd-system.conf(5), user@.service(5), systemd.directives(7), systemd.index(7), pam_systemd(8), systemd-oomd.service(8)
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