SYSTEMD.RESOURCE-CONTROL(5) systemd.resource-controlSYSTEMD.RESOURCE-CONTROL(5)
NAME
systemd.resource-control - Resource control unit settings
SYNOPSIS
slice.slice, scope.scope, service.service, socket.socket, mount.mount,
swap.swap
DESCRIPTION
Unit configuration files for services, slices, scopes, sockets, mount
points, and swap devices share a subset of configuration options for
resource control of spawned processes. Internally, this relies on the
Linux Control Groups (cgroups) kernel concept for organizing processes
in a hierarchical tree of named groups for the purpose of resource
management.
This man page lists the configuration options shared by those six unit
types. See systemd.unit(5) for the common options of all unit
configuration files, and systemd.slice(5), systemd.scope(5),
systemd.service(5), systemd.socket(5), systemd.mount(5), and
systemd.swap(5) for more information on the specific unit configuration
files. The resource control configuration options are configured in the
[Slice], [Scope], [Service], [Socket], [Mount], or [Swap] sections,
depending on the unit type.
In addition, options which control resources available to programs
executed by systemd are listed in systemd.exec(5). Those options
complement options listed here.
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 do
not 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 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= does not 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.
Alternatively, a percentage value may be specified, which is taken
relative to the specified swap size on the system. 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= does not
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 ::1/128 │ All addresses on the │
│ │ │ local loopback │
├───────────────┼──────────────────────┼──────────────────────┤
│ link-local │ 169.254.0.0/16 │ All link-local IP │
│ │ fe80::/64 │ addresses │
├───────────────┼──────────────────────┼──────────────────────┤
│ multicast │ 224.0.0.0/4 ff00::/8 │ All IP 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 to be 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 are not 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 is 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
the cgroup of this unit. Takes a percentage value between 0% and
100%, inclusive. Defaults to 0%, which means to use the default set
by oomd.conf(5). This property is ignored unless
ManagedOOMMemoryPressure=kill.
Added in version 247.
ManagedOOMMemoryPressureDurationSec=
Overrides the default memory pressure duration set by oomd.conf(5)
for the cgroup of this unit. The specified value supports a time
unit such as "ms" or "μs", see systemd.time(7) for details on the
permitted syntax. Must be set to either empty or a value of at least
1s. Defaults to empty, which means to use the default set by
oomd.conf(5). This property is ignored unless
ManagedOOMMemoryPressure=kill.
Added in version 257.
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 a
boolean or one of "auto" and "skip". If "no", 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 "yes", 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 is 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. See also systemd-coredump(8).
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.
SEE ALSO
systemd(1), systemd-system.conf(5), systemd.unit(5), systemd.service(5),
systemd.slice(5), systemd.scope(5), systemd.socket(5), systemd.mount(5),
systemd.swap(5), systemd.exec(5), systemd.directives(7),
systemd.special(7), systemd-oomd.service(8), The documentation for
control groups and specific controllers in the Linux kernel: Control
Groups v2[2]
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
systemd 257.9 SYSTEMD.RESOURCE-CONTROL(5)
Generated by dwww version 1.16 on Tue Dec 16 04:00:55 CET 2025.