systemd.resource-control(5) — Linux manual page

SYSTEMD...E-CONTROL(5)  systemd.resource-control  SYSTEMD...E-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.

   Enabling and disabling controllers
       Controllers in the cgroup hierarchy are hierarchical, and
       resource control is realized by distributing resource assignments
       between siblings in branches of the cgroup hierarchy. There is no
       need to explicitly enable a cgroup controller for a unit.
       systemd will instruct the kernel to enable a controller for a
       given unit when this unit has configuration for a given
       controller. For example, when CPUWeight= is set, the cpu
       controller will be enabled, and when TasksMax= are set, the pids
       controller will be enabled. In addition, various controllers may
       be also be enabled explicitly via the
       MemoryAccounting=/TasksAccounting=/IOAccounting= settings.
       Because of how the cgroup hierarchy works, controllers will be
       automatically enabled for all parent units and for any sibling
       units starting with the lowest level at which a controller is
       enabled. Units for which a controller is enabled may be subject
       to resource control even if they don't have any explicit
       configuration.

       Setting Delegate= enables any delegated controllers for that unit
       (see below). The delegatee may then enable controllers for its
       children as appropriate. In particular, if the delegatee is
       systemd (in the user@.service unit), it will repeat the same
       logic as the system instance and enable controllers for user
       units which have resource limits configured, and their siblings
       and parents and parents' siblings.

       Controllers may be disabled for parts of the cgroup hierarchy
       with DisableControllers= (see below).

       Example 1. Enabling and disabling controllers

                                 -.slice
                                /       \
                         /-----/         \--------------\
                        /                                \
                 system.slice                       user.slice
                   /       \                          /      \
                  /         \                        /        \
                 /           \              user@42.service  user@1000.service
                /             \             Delegate=        Delegate=yes
           a.service       b.slice                             /        \
           CPUWeight=20   DisableControllers=cpu              /          \
                            /  \                      app.slice      session.slice
                           /    \                     CPUWeight=100  CPUWeight=100
                          /      \
                  b1.service   b2.service
                               CPUWeight=1000

       In this hierarchy, the cpu controller is enabled for all units
       shown except b1.service and b2.service. Because there is no
       explicit configuration for system.slice and user.slice, CPU
       resources will be split equally between them. Similarly,
       resources are allocated equally between children of user.slice
       and between the child slices beneath user@1000.service. Assuming
       that there is no further configuration of resources or delegation
       below slices app.slice or session.slice, the cpu controller would
       not be enabled for units in those slices and CPU resources would
       be further allocated using other mechanisms, e.g. based on nice
       levels. The manager for user 42 has delegation enabled without
       any controllers, i.e. it can manipulate its subtree of the cgroup
       hierarchy, but without resource control.

       In the slice system.slice, CPU resources are split 1:6 for
       service a.service, and 5:6 for slice b.slice, because slice
       b.slice gets the default value of 100 for cpu.weight when
       CPUWeight= is not set.

       CPUWeight= setting in service b2.service is neutralized by
       DisableControllers= in slice b.slice, so the cpu controller would
       not be enabled for services b1.service and b2.service, and CPU
       resources would be further allocated using other mechanisms, e.g.
       based on nice levels.

   Setting resource controls for a group of related units
       As described in systemd.unit(5), the settings listed here may be
       set through the main file of a unit and drop-in snippets in *.d/
       directories. The list of directories searched for drop-ins
       includes names formed by repeatedly truncating the unit name
       after all dashes. This is particularly convenient to set resource
       limits for a group of units with similar names.

       For example, every user gets their own slice user-nnn.slice.
       Drop-ins with local configuration that affect user 1000 may be
       placed in /etc/systemd/system/user-1000.slice,
       /etc/systemd/system/user-1000.slice.d/*.conf, but also
       /etc/systemd/system/user-.slice.d/*.conf. This last directory
       applies to all user slices.

       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:

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

OPTIONS

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

CPU Accounting and Control
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).

Under the unified cgroup hierarchy, CPU accounting is
available for all units and this setting has no effect.

Added in version 208.

CPUWeight=weight, StartupCPUWeight=weight
These settings control the cpu controller in the unified
hierarchy.

These options accept an integer value or a the special string
"idle":

• If set to an integer value, assign the specified CPU time
weight to the processes executed, if the unified control
group hierarchy is used on the system. These options
control the "cpu.weight" control group attribute. The
allowed range is 1 to 10000. Defaults to unset, but the
kernel default is 100. For details about this control
group attribute, see Control Groups v2[2] and CFS
Scheduler[3]. The available CPU time is split up among
all units within one slice relative to their CPU time
weight. A higher weight means more CPU time, a lower
weight means less.

• If set to the special string "idle", mark the cgroup for
"idle scheduling", which means that it will get CPU
resources only when there are no processes not marked in
this way to execute in this cgroup or its siblings. This
setting corresponds to the "cpu.idle" cgroup attribute.

Note that this value only has an effect on cgroup-v2, for
cgroup-v1 it is equivalent to the minimum weight.

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

In addition to the resource allocation performed by the cpu
controller, the kernel may automatically divide resources
based on session-id grouping, see "The autogroup feature" in
sched(7). The effect of this feature is similar to the cpu
controller with no explicit configuration, so users should be
careful to not mistake one for the other.

Added in version 232.

CPUQuota=
This setting controls the cpu controller in the unified
hierarchy.

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 CFS Bandwidth Control[4]. Setting CPUQuota=
to an empty value unsets the quota.

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

Added in version 213.

CPUQuotaPeriodSec=
This setting controls the cpu controller in the unified
hierarchy.

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[3].

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

Added in version 242.

AllowedCPUs=, StartupAllowedCPUs=
This setting controls the cpuset controller in the unified
hierarchy.

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= or StartupAllowedCPUs= 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=.

While StartupAllowedCPUs= applies to the startup and shutdown
phases of the system, AllowedCPUs= applies to normal runtime
of the system, and if the former is not set also to the
startup and shutdown phases. Using StartupAllowedCPUs= allows
prioritizing specific services at boot-up and shutdown
differently than during normal runtime.

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

Added in version 244.

Memory Accounting and Control
MemoryAccounting=
This setting controls the memory controller in the unified
hierarchy.

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).

Added in version 208.

MemoryMin=bytes, MemoryLow=bytes, StartupMemoryLow=bytes,
DefaultStartupMemoryLow=bytes
These settings control the memory controller in the unified
hierarchy.

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[5].

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=, or DefaultStartupMemoryLow= which has the
same semantics as StartupMemoryLow=. 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.

While StartupMemoryLow= applies to the startup and shutdown
phases of the system, MemoryMin= applies to normal runtime of
the system, and if the former is not set also to the startup
and shutdown phases. Using StartupMemoryLow= allows
prioritizing specific services at boot-up and shutdown
differently than during normal runtime.

Added in version 240.

MemoryHigh=bytes, StartupMemoryHigh=bytes
These settings control the memory controller in the unified
hierarchy.

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[5].
The effective configuration is reported as
EffectiveMemoryHigh= (see also EffectiveMemoryMax=).

While StartupMemoryHigh= applies to the startup and shutdown
phases of the system, MemoryHigh= applies to normal runtime
of the system, and if the former is not set also to the
startup and shutdown phases. Using StartupMemoryHigh= allows
prioritizing specific services at boot-up and shutdown
differently than during normal runtime.

Added in version 231.

MemoryMax=bytes, StartupMemoryMax=bytes
These settings control the memory controller in the unified
hierarchy.

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[5]. The
effective configuration is reported as EffectiveMemoryMax=
(the value is the most stringent limit of the unit and parent
slices and it is capped by physical memory).

While StartupMemoryMax= applies to the startup and shutdown
phases of the system, MemoryMax= applies to normal runtime of
the system, and if the former is not set also to the startup
and shutdown phases. Using StartupMemoryMax= allows
prioritizing specific services at boot-up and shutdown
differently than during normal runtime.

Added in version 231.

MemorySwapMax=bytes, StartupMemorySwapMax=bytes
These settings control the memory controller in the unified
hierarchy.

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. These settings control the
"memory.swap.max" control group attribute. For details about
this control group attribute, see Memory Interface Files[5].

While StartupMemorySwapMax= applies to the startup and
shutdown phases of the system, MemorySwapMax= applies to
normal runtime of the system, and if the former is not set
also to the startup and shutdown phases. Using
StartupMemorySwapMax= allows prioritizing specific services
at boot-up and shutdown differently than during normal
runtime.

Added in version 232.

MemoryZSwapMax=bytes, StartupMemoryZSwapMax=bytes
These settings control the memory controller in the unified
hierarchy.

Specify the absolute limit on zswap usage of the processes in
this unit. Zswap is a lightweight compressed cache for swap
pages. It takes pages that are in the process of being
swapped out and attempts to compress them into a dynamically
allocated RAM-based memory pool. If the limit specified is
hit, no entries from this unit will be stored in the pool
until existing entries are faulted back or written out to
disk. See the kernel's Zswap[6] documentation for more
details.

Takes a size in bytes. If the value is suffixed with K, M, G
or T, the specified size is parsed as Kilobytes, Megabytes,
Gigabytes, or Terabytes (with the base 1024), respectively.
If assigned the special value "infinity", no limit is
applied. These settings control the "memory.zswap.max"
control group attribute. For details about this control group
attribute, see Memory Interface Files[5].

While StartupMemoryZSwapMax= applies to the startup and
shutdown phases of the system, MemoryZSwapMax= applies to
normal runtime of the system, and if the former is not set
also to the startup and shutdown phases. Using
StartupMemoryZSwapMax= allows prioritizing specific services
at boot-up and shutdown differently than during normal
runtime.

Added in version 253.

MemoryZSwapWriteback=
This setting controls the memory controller in the unified
hierarchy.

Takes a boolean argument. When true, pages stored in the
Zswap cache are permitted to be written to the backing
storage, false otherwise. Defaults to true. This allows
disabling writeback of swap pages for IO-intensive
applications, while retaining the ability to store compressed
pages in Zswap. See the kernel's Zswap[6] documentation for
more details.

Added in version 256.

AllowedMemoryNodes=, StartupAllowedMemoryNodes=
These settings control the cpuset controller in the unified
hierarchy.

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 NUMA nodes
indices separated by a dash.

Setting AllowedMemoryNodes= or StartupAllowedMemoryNodes=
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=.

While StartupAllowedMemoryNodes= applies to the startup and
shutdown phases of the system, AllowedMemoryNodes= applies to
normal runtime of the system, and if the former is not set
also to the startup and shutdown phases. Using
StartupAllowedMemoryNodes= allows prioritizing specific
services at boot-up and shutdown differently than during
normal runtime.

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

Added in version 244.

Process Accounting and Control
TasksAccounting=
This setting controls the pids controller in the unified
hierarchy.

Turn on task accounting for this unit. Takes a boolean
argument. If enabled, the kernel will keep track of the total
number of tasks in the unit and its children. This number
includes both kernel threads and userspace processes, with
each thread counted 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).

Added in version 227.

TasksMax=N
This setting controls the pids controller in the unified
hierarchy.

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, the pids controller[7]. The
effective configuration is reported as EffectiveTasksMax=.

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

Added in version 227.

IO Accounting and Control
IOAccounting=
This setting controls the io controller in the unified
hierarchy.

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).

Added in version 230.

IOWeight=weight, StartupIOWeight=weight
These settings control the io controller in the unified
hierarchy.

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. A higher weight means more I/O bandwidth, a lower
weight means less.

While StartupIOWeight= applies to the startup and shutdown
phases of the system, IOWeight= applies to the later runtime
of the system, and if the former is not set also to the
startup and shutdown phases. This allows prioritizing
specific services at boot-up and shutdown differently than
during runtime.

Added in version 230.

IODeviceWeight=device weight
This setting controls the io controller in the unified
hierarchy.

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].

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.

Added in version 230.

IOReadBandwidthMax=device bytes, IOWriteBandwidthMax=device bytes
These settings control the io controller in the unified
hierarchy.

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].

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

Added in version 230.

IOReadIOPSMax=device IOPS, IOWriteIOPSMax=device IOPS
These settings control the io controller in the unified
hierarchy.

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].

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

Added in version 230.

IODeviceLatencyTargetSec=device target
This setting controls the io controller in the unified
hierarchy.

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.

Added in version 240.

Network Accounting and Control
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).

Note that this functionality is currently only available for
system services, not for per-user services.

Added in version 235.

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 use case.

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.

This option cannot be bypassed by prefixing "+" to the
executable path in the service unit, as it applies to the
whole control group.

Added in version 235.

SocketBindAllow=bind-rule, SocketBindDeny=bind-rule
Configures restrictions on the ability of unit processes to
invoke bind(2) on a socket. Both allow and deny rules may
defined that restrict which addresses a socket may be bound
to.

bind-rule describes socket properties such as address-family,
transport-protocol and ip-ports.

bind-rule := {
[address-family:][transport-protocol:][ip-ports] | any }

address-family := { ipv4 | ipv6 }

transport-protocol := { tcp | udp }

ip-ports := { ip-port | ip-port-range }

An optional address-family expects ipv4 or ipv6 values. If
not specified, a rule will be matched for both IPv4 and IPv6
addresses and applied depending on other socket fields, e.g.
transport-protocol, ip-port.

An optional transport-protocol expects tcp or udp transport
protocol names. If not specified, a rule will be matched for
any transport protocol.

An optional ip-port value must lie within 1...65535 interval
inclusively, i.e. dynamic port 0 is not allowed. A range of
sequential ports is described by ip-port-range :=
ip-port-low-ip-port-high, where ip-port-low is smaller than
or equal to ip-port-high and both are within 1...65535
inclusively.

A special value any can be used to apply a rule to any
address family, transport protocol and any port with a
positive value.

To allow multiple rules assign SocketBindAllow= or
SocketBindDeny= multiple times. To clear the existing
assignments pass an empty SocketBindAllow= or SocketBindDeny=
assignment.

For each of SocketBindAllow= and SocketBindDeny=, maximum
allowed number of assignments is 128.

• Binding to a socket is allowed when a socket address
matches an entry in the SocketBindAllow= list.

• Otherwise, binding is denied when the socket address
matches an entry in the SocketBindDeny= list.

• Otherwise, binding is allowed.

The feature is implemented with cgroup/bind4 and cgroup/bind6
cgroup-bpf hooks.

Note that these settings apply to any bind(2) system call
invocation by the unit processes, regardless in which network
namespace they are placed. Or in other words: changing the
network namespace is not a suitable mechanism for escaping
these restrictions on bind().

Examples:

...
# Allow binding IPv6 socket addresses with a port greater than or equal to 10000.
[Service]
SocketBindAllow=ipv6:10000-65535
SocketBindDeny=any
...
# Allow binding IPv4 and IPv6 socket addresses with 1234 and 4321 ports.
[Service]
SocketBindAllow=1234
SocketBindAllow=4321
SocketBindDeny=any
...
# Deny binding IPv6 socket addresses.
[Service]
SocketBindDeny=ipv6
...
# Deny binding IPv4 and IPv6 socket addresses.
[Service]
SocketBindDeny=any
...
# Allow binding only over TCP
[Service]
SocketBindAllow=tcp
SocketBindDeny=any
...
# Allow binding only over IPv6/TCP
[Service]
SocketBindAllow=ipv6:tcp
SocketBindDeny=any
...
# Allow binding ports within 10000-65535 range over IPv4/UDP.
[Service]
SocketBindAllow=ipv4:udp:10000-65535
SocketBindDeny=any
...

This option cannot be bypassed by prefixing "+" to the
executable path in the service unit, as it applies to the
whole control group.

Added in version 249.

RestrictNetworkInterfaces=
Takes a list of space-separated network interface names. This
option restricts the network interfaces that processes of
this unit can use. By default processes can only use the
network interfaces listed (allow-list). If the first
character of the rule is "~", the effect is inverted: the
processes can only use network interfaces not listed
(deny-list).

This option can appear multiple times, in which case the
network interface names are merged. If the empty string is
assigned the set is reset, all prior assignments will have
not effect.

If you specify both types of this option (i.e. allow-listing
and deny-listing), the first encountered will take precedence
and will dictate the default action (allow vs deny). Then the
next occurrences of this option will add or delete the listed
network interface names from the set, depending of its type
and the default action.

The loopback interface ("lo") is not treated in any special
way, you have to configure it explicitly in the unit file.

Example 1: allow-list

RestrictNetworkInterfaces=eth1
RestrictNetworkInterfaces=eth2

Programs in the unit will be only able to use the eth1 and
eth2 network interfaces.

Example 2: deny-list

RestrictNetworkInterfaces=~eth1 eth2

Programs in the unit will be able to use any network
interface but eth1 and eth2.

Example 3: mixed

RestrictNetworkInterfaces=eth1 eth2
RestrictNetworkInterfaces=~eth1

Programs in the unit will be only able to use the eth2
network interface.

This option cannot be bypassed by prefixing "+" to the
executable path in the service unit, as it applies to the
whole control group.

Added in version 250.

NFTSet=family:table:set
This setting provides a method for integrating dynamic
cgroup, user and group IDs into firewall rules with NFT[9]
sets. The benefit of using this setting is to be able to use
the IDs as selectors in firewall rules easily and this in
turn allows more fine grained filtering. NFT rules for cgroup
matching use numeric cgroup IDs, which change every time a
service is restarted, making them hard to use in systemd
environment otherwise. Dynamic and random IDs used by
DynamicUser= can be also integrated with this setting.

This option expects a whitespace separated list of NFT set
definitions. Each definition consists of a colon-separated
tuple of source type (one of "cgroup", "user" or "group"),
NFT address family (one of "arp", "bridge", "inet", "ip",
"ip6", or "netdev"), table name and set name. The names of
tables and sets must conform to lexical restrictions of NFT
table names. The type of the element used in the NFT filter
must match the type implied by the directive ("cgroup",
"user" or "group") as shown in the table below. When a
control group or a unit is realized, the corresponding ID
will be appended to the NFT sets and it will be be removed
when the control group or unit is removed. systemd only
inserts elements to (or removes from) the sets, so the
related NFT rules, tables and sets must be prepared elsewhere
in advance. Failures to manage the sets will be ignored.

Table 2. Defined source type values
┌─────────────┬──────────────────┬───────────────────┐
│ Source type │ Description │ Corresponding NFT │
│ │ │ type name │
├─────────────┼──────────────────┼───────────────────┤
│ "cgroup" │ control group ID │ "cgroupsv2" │
├─────────────┼──────────────────┼───────────────────┤
│ "user" │ user ID │ "meta skuid" │
├─────────────┼──────────────────┼───────────────────┤
│ "group" │ group ID │ "meta skgid" │
└─────────────┴──────────────────┴───────────────────┘

If the firewall rules are reinstalled so that the contents of
NFT sets are destroyed, command systemctl daemon-reload can
be used to refill the sets.

Example:

[Unit]
NFTSet=cgroup:inet:filter:my_service user:inet:filter:serviceuser

Corresponding NFT rules:

table inet filter {
set my_service {
type cgroupsv2
}
set serviceuser {
typeof meta skuid
}
chain x {
socket cgroupv2 level 2 @my_service accept
drop
}
chain y {
meta skuid @serviceuser accept
drop
}
}

This option is only available for system services and is not
supported for services running in per-user instances of the
service manager.

Added in version 255.

BPF Programs
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.

If the path BPF_FS_PROGRAM_PATH in IPIngressFilterPath=
assignment is already being handled by BPFProgram= ingress
hook, e.g. BPFProgram=ingress:BPF_FS_PROGRAM_PATH, the
assignment will be still considered valid and the program
will be attached to a cgroup. Same for IPEgressFilterPath=
path and egress hook.

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 use case.

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.

Added in version 243.

BPFProgram=type:program-path
BPFProgram= allows attaching custom BPF programs to the
cgroup of a unit. (This generalizes the functionality exposed
via IPEgressFilterPath= and IPIngressFilterPath= for other
hooks.) Cgroup-bpf hooks in the form of BPF programs loaded
to the BPF filesystem are attached with cgroup-bpf attach
flags determined by the unit. For details about attachment
types and flags see bpf.h[10]. Also refer to the general BPF
documentation[11].

The specification of BPF program consists of a pair of BPF
program type and program path in the file system, with ":" as
the separator: type:program-path.

The BPF program type is equivalent to the BPF attach type
used in bpftool(8) It may be one of egress, ingress,
sock_create, sock_ops, device, bind4, bind6, connect4,
connect6, post_bind4, post_bind6, sendmsg4, sendmsg6, sysctl,
recvmsg4, recvmsg6, getsockopt, or setsockopt.

The specified program path must be an absolute path
referencing a BPF program inode in the bpffs file system
(which generally means it must begin with /sys/fs/bpf/). If a
specified program does not exist (i.e. has not been uploaded
to the BPF subsystem of the kernel yet), it will not be
installed but unit activation will continue (a warning will
be printed to the logs).

Setting BPFProgram= to an empty value makes previous
assignments ineffective.

Multiple assignments of the same program type/path pair have
the same effect as a single assignment: the program will be
attached just once.

If BPF egress pinned to program-path path is already being
handled by IPEgressFilterPath=, BPFProgram= assignment will
be considered valid and BPFProgram= will be attached to a
cgroup. Similarly for ingress hook and IPIngressFilterPath=
assignment.

BPF programs passed with BPFProgram= are attached to the
cgroup of a unit with BPF attach flag multi, that allows
further attachments of the same type within cgroup hierarchy
topped by the unit cgroup.

Examples:

BPFProgram=egress:/sys/fs/bpf/egress-hook
BPFProgram=bind6:/sys/fs/bpf/sock-addr-hook

Added in version 249.

Device Access
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 nodes by
the unit (mknod), respectively. This functionality is
implemented using eBPF filtering.

When access to all physical devices should be disallowed,
PrivateDevices= may be used instead. See systemd.exec(5).

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
...

This option cannot be bypassed by prefixing "+" to the
executable path in the service unit, as it applies to the
whole control group.

Added in version 208.

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

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

Added in version 208.

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

Added in version 208.

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

Added in version 208.

This option cannot be bypassed by prefixing "+" to the
executable path in the service unit, as it applies to the
whole control group.

Added in version 208.

Control Group Management
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.

Added in version 208.

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 at the level of the
unit's control group and above (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 (possibly empty) 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. Assigning the empty
string will enable delegation, but reset the list of
controllers, and all assignments prior to this will have no
effect. Note that additional controllers other than the ones
specified might be made available as well, depending on
configuration of the containing slice unit or other units
contained in it. 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.

Note that because of the hierarchical nature of cgroup
hierarchy, any controllers that are delegated will be enabled
for the parent and sibling units of the unit with delegation.

For further details on the delegation model consult Control
Group APIs and Delegation[12].

Added in version 218.

DelegateSubgroup=
Place unit processes in the specified subgroup of the unit's
control group. Takes a valid control group name (not a path!)
as parameter, or an empty string to turn this feature off.
Defaults to off. The control group name must be usable as
filename and avoid conflicts with the kernel's control group
attribute files (i.e. cgroup.procs is not an acceptable
name, since the kernel exposes a native control group
attribute file by that name). This option has no effect
unless control group delegation is turned on via Delegate=,
see above. Note that this setting only applies to "main"
processes of a unit, i.e. for services to ExecStart=, but not
for ExecReload= and similar. If delegation is enabled, the
latter are always placed inside a subgroup named .control.
The specified subgroup is automatically created (and
potentially ownership is passed to the unit's configured
user/group) when a process is started in it.

This option is useful to avoid manually moving the invoked
process into a subgroup after it has been started. Since no
processes should live in inner nodes of the control group
tree it's almost always necessary to run the main
("supervising") process of a unit that has delegation turned
on in a subgroup.

Added in version 254.

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 configuration in child units from
being able to implicitly or explicitly enable a controller.
Defaults to empty.

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.

It may not be possible to disable a controller after units
have been started, 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.

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

Added in version 240.

Memory Pressure Control
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, the unit becomes a candidate for monitoring
by systemd-oomd. If the cgroup passes the limits set by
oomd.conf(5) or the unit configuration, systemd-oomd will
select a descendant cgroup and send SIGKILL to all of the
processes under it. 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 result
in 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 a candidate for systemd-oomd to
terminate.

Added in version 247.

ManagedOOMMemoryPressureLimit=
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 to use the default set by oomd.conf(5).

Added in version 247.

ManagedOOMPreference=none|avoid|omit
Allows deprioritizing or omitting this unit's cgroup as a
candidate when systemd-oomd needs to act. Requires support
for extended attributes (see xattr(7)) in order to use avoid
or omit.

When calculating candidates to relieve swap usage,
systemd-oomd will only respect these extended attributes if
the unit's cgroup is owned by root.

When calculating candidates to relieve memory pressure,
systemd-oomd will only respect these extended attributes if
the unit's cgroup is owned by root, or if the unit's cgroup
owner, and the owner of the monitored ancestor cgroup are the
same. For example, if systemd-oomd is calculating candidates
for -.slice, then extended attributes set on descendants of
/user.slice/user-1000.slice/user@1000.service/ will be
ignored because the descendants are owned by UID 1000, and
-.slice is owned by UID 0. But, if calculating candidates for
/user.slice/user-1000.slice/user@1000.service/, then extended
attributes set on the descendants would be respected.

If this property is set to avoid, the service manager will
convey this to systemd-oomd, which will only select this
cgroup if there are no other viable candidates.

If this property is set to omit, the service manager will
convey this to systemd-oomd, which will ignore this cgroup as
a candidate and will not perform any actions on it.

It is recommended to use avoid and omit sparingly, as it can
adversely affect systemd-oomd's kill behavior. Also note that
these extended attributes are not applied recursively to
cgroups under this unit's cgroup.

Defaults to none which means systemd-oomd will rank this
unit's cgroup as defined in systemd-oomd.service(8) and
oomd.conf(5).

Added in version 248.

MemoryPressureWatch=
Controls memory pressure monitoring for invoked processes.
Takes one of "off", "on", "auto" or "skip". If "off" tells
the service not to watch for memory pressure events, by
setting the $MEMORY_PRESSURE_WATCH environment variable to
the literal string /dev/null. If "on" tells the service to
watch for memory pressure events. This enables memory
accounting for the service, and ensures the memory.pressure
cgroup attribute file is accessible for reading and writing
by the service's user. It then sets the
$MEMORY_PRESSURE_WATCH environment variable for processes
invoked by the unit to the file system path to this file. The
threshold information configured with
MemoryPressureThresholdSec= is encoded in the
$MEMORY_PRESSURE_WRITE environment variable. If the "auto"
value is set the protocol is enabled if memory accounting is
anyway enabled for the unit, and disabled otherwise. If set
to "skip" the logic is neither enabled, nor disabled and the
two environment variables are not set.

Note that services are free to use the two environment
variables, but it's unproblematic if they ignore them. Memory
pressure handling must be implemented individually in each
service, and usually means different things for different
software. For further details on memory pressure handling see
Memory Pressure Handling in systemd[13].

Services implemented using sd-event(3) may use
sd_event_add_memory_pressure(3) to watch for and handle
memory pressure events.

If not explicit set, defaults to the
DefaultMemoryPressureWatch= setting in
systemd-system.conf(5).

Added in version 254.

MemoryPressureThresholdSec=
Sets the memory pressure threshold time for memory pressure
monitor as configured via MemoryPressureWatch=. Specifies the
maximum allocation latency before a memory pressure event is
signalled to the service, per 2s window. If not specified
defaults to the DefaultMemoryPressureThresholdSec= setting in
systemd-system.conf(5) (which in turn defaults to 200ms). The
specified value expects a time unit such as "ms" or "μs", see
systemd.time(7) for details on the permitted syntax.

Added in version 254.

Coredump Control
CoredumpReceive=
Takes a boolean argument. This setting is used to enable
coredump forwarding for containers that belong to this unit's
cgroup. Units with CoredumpReceive=yes must also be
configured with Delegate=yes. Defaults to false.

When systemd-coredump is handling a coredump for a process
from a container, if the container's leader process is a
descendant of a cgroup with CoredumpReceive=yes and
Delegate=yes, then systemd-coredump will attempt to forward
the coredump to systemd-coredump within the container.

Added in version 255.

HISTORY

       systemd 252
           Options for controlling the Legacy Control Group Hierarchy
           (Control Groups version 1[14]) are now fully deprecated:
           CPUShares=weight, StartupCPUShares=weight, MemoryLimit=bytes,
           BlockIOAccounting=, BlockIOWeight=weight,
           StartupBlockIOWeight=weight, BlockIODeviceWeight=device
           weight, BlockIOReadBandwidth=device bytes,
           BlockIOWriteBandwidth=device bytes. Please switch to the
           unified cgroup hierarchy.

           Added in version 252.

NOTES

        1. New Control Group Interfaces
           https://systemd.io/CONTROL_GROUP_INTERFACE

        2. Control Groups v2
           https://docs.kernel.org/admin-guide/cgroup-v2.html

        3. CFS Scheduler
           https://docs.kernel.org/scheduler/sched-design-CFS.html

        4. CFS Bandwidth Control
           https://docs.kernel.org/scheduler/sched-bwc.html

        5. Memory Interface Files
           https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files

        6. Zswap
           https://docs.kernel.org/admin-guide/mm/zswap.html

        7. pids controller
           https://docs.kernel.org/admin-guide/cgroup-v2.html#pid

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

        9. NFT
           https://netfilter.org/projects/nftables/index.html

       10. bpf.h
           https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/include/uapi/linux/bpf.h

       11. BPF documentation
           https://docs.kernel.org/bpf/

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

       13. Memory Pressure Handling in systemd
           https://systemd.io/MEMORY_PRESSURE

       14. Control Groups version 1
           https://docs.kernel.org/admin-guide/cgroup-v1/index.html

COLOPHON

       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 2024-06-14.  (At that
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       is a better or more up-to-date source for the page, or you have
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 257~devel                                 SYSTEMD...E-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)

...
https://man7.org/linux/man-pages/man5/systemd.resource-control.5.html

systemd.resource-control(5) — Linux manual page

NAME

SYNOPSIS

DESCRIPTION

IMPLICIT DEPENDENCIES

OPTIONS

HISTORY

SEE ALSO

NOTES

COLOPHON