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NAME | SYNOPSIS | DESCRIPTION | IMPLICIT DEPENDENCIES | UNIFIED AND LEGACY CONTROL GROUP HIERARCHIES | OPTIONS | DEPRECATED OPTIONS | SEE ALSO | NOTES | COLOPHON |
SYSTEMD.RESOURCE-CONTROL(5)ystemd.resource-controlYSTEMD.RESOURCE-CONTROL(5)
systemd.resource-control - Resource control unit settings
slice.slice, scope.scope, service.service, socket.socket,
mount.mount, swap.swap
Unit configuration files for services, slices, scopes, sockets, mount
points, and swap devices share a subset of configuration options for
resource control of spawned processes. Internally, this relies on the
Linux Control Groups (cgroups) kernel concept for organizing
processes in a hierarchical tree of named groups for the purpose of
resource management.
This man page lists the configuration options shared by those six
unit types. See systemd.unit(5) for the common options of all unit
configuration files, and systemd.slice(5), systemd.scope(5),
systemd.service(5), systemd.socket(5), systemd.mount(5), and
systemd.swap(5) for more information on the specific unit
configuration files. The resource control configuration options are
configured in the [Slice], [Scope], [Service], [Socket], [Mount], or
[Swap] sections, depending on the unit type.
In addition, options which control resources available to programs
executed by systemd are listed in systemd.exec(5). Those options
complement options listed here.
See the New Control Group Interfaces[1] for an introduction on how to
make use of resource control APIs from programs.
The following dependencies are implicitly added:
· Units with the Slice= setting set automatically acquire Requires=
and After= dependencies on the specified slice unit.
The unified control group hierarchy is the new version of kernel
control group interface, see Control Groups v2[2]. Depending on the
resource type, there are differences in resource control
capabilities. Also, because of interface changes, some resource types
have separate set of options on the unified hierarchy.
CPU
CPUWeight= and StartupCPUWeight= replace CPUShares= and
StartupCPUShares=, respectively.
The "cpuacct" controller does not exist separately on the unified
hierarchy.
Memory
MemoryMax= replaces MemoryLimit=. MemoryLow= and MemoryHigh= are
effective only on unified hierarchy.
IO
"IO"-prefixed settings are a superset of and replace
"BlockIO"-prefixed ones. On unified hierarchy, IO resource
control also applies to buffered writes.
To ease the transition, there is best-effort translation between the
two versions of settings. For each controller, if any of the settings
for the unified hierarchy are present, all settings for the legacy
hierarchy are ignored. If the resulting settings are for the other
type of hierarchy, the configurations are translated before
application.
Legacy control group hierarchy (see Control Groups version 1[3]),
also called cgroup-v1, doesn't allow safe delegation of controllers
to unprivileged processes. If the system uses the legacy control
group hierarchy, resource control is disabled for the systemd user
instance, see systemd(1).
Units of the types listed above can have settings for resource
control configuration:
CPUAccounting=
Turn on CPU usage accounting for this unit. Takes a boolean
argument. Note that turning on CPU accounting for one unit will
also implicitly turn it on for all units contained in the same
slice and for all its parent slices and the units contained
therein. The system default for this setting may be controlled
with DefaultCPUAccounting= in systemd-system.conf(5).
CPUWeight=weight, StartupCPUWeight=weight
Assign the specified CPU time weight to the processes executed,
if the unified control group hierarchy is used on the system.
These options take an integer value and control the "cpu.weight"
control group attribute. The allowed range is 1 to 10000.
Defaults to 100. For details about this control group attribute,
see Control Groups v2[2] and CFS Scheduler[4]. The available CPU
time is split up among all units within one slice relative to
their CPU time weight.
While StartupCPUWeight= only applies to the startup phase of the
system, CPUWeight= applies to normal runtime of the system, and
if the former is not set also to the startup phase. Using
StartupCPUWeight= allows prioritizing specific services at
boot-up differently than during normal runtime.
These settings replace CPUShares= and StartupCPUShares=.
CPUQuota=
Assign the specified CPU time quota to the processes executed.
Takes a percentage value, suffixed with "%". The percentage
specifies how much CPU time the unit shall get at maximum,
relative to the total CPU time available on one CPU. Use values >
100% for allotting CPU time on more than one CPU. This controls
the "cpu.max" attribute on the unified control group hierarchy
and "cpu.cfs_quota_us" on legacy. For details about these control
group attributes, see Control Groups v2[2] and sched-bwc.txt[5].
Example: CPUQuota=20% ensures that the executed processes will
never get more than 20% CPU time on one CPU.
CPUQuotaPeriodSec=
Assign the duration over which the CPU time quota specified by
CPUQuota= is measured. Takes a time duration value in seconds,
with an optional suffix such as "ms" for milliseconds (or "s" for
seconds.) The default setting is 100ms. The period is clamped to
the range supported by the kernel, which is [1ms, 1000ms].
Additionally, the period is adjusted up so that the quota
interval is also at least 1ms. Setting CPUQuotaPeriodSec= to an
empty value resets it to the default.
This controls the second field of "cpu.max" attribute on the
unified control group hierarchy and "cpu.cfs_period_us" on
legacy. For details about these control group attributes, see
Control Groups v2[2] and CFS Scheduler[4].
Example: CPUQuotaPeriodSec=10ms to request that the CPU quota is
measured in periods of 10ms.
AllowedCPUs=
Restrict processes to be executed on specific CPUs. Takes a list
of CPU indices or ranges separated by either whitespace or
commas. CPU ranges are specified by the lower and upper CPU
indices separated by a dash.
Setting AllowedCPUs= doesn't guarantee that all of the CPUs will
be used by the processes as it may be limited by parent units.
The effective configuration is reported as EffectiveCPUs=.
This setting is supported only with the unified control group
hierarchy.
AllowedMemoryNodes=
Restrict processes to be executed on specific memory NUMA nodes.
Takes a list of memory NUMA nodes indices or ranges separated by
either whitespace or commas. Memory NUMA nodes ranges are
specified by the lower and upper CPU indices separated by a dash.
Setting AllowedMemoryNodes= doesn't guarantee that all of the
memory NUMA nodes will be used by the processes as it may be
limited by parent units. The effective configuration is reported
as EffectiveMemoryNodes=.
This setting is supported only with the unified control group
hierarchy.
MemoryAccounting=
Turn on process and kernel memory accounting for this unit. Takes
a boolean argument. Note that turning on memory accounting for
one unit will also implicitly turn it on for all units contained
in the same slice and for all its parent slices and the units
contained therein. The system default for this setting may be
controlled with DefaultMemoryAccounting= in
systemd-system.conf(5).
MemoryMin=bytes
Specify the memory usage protection of the executed processes in
this unit. If the memory usages of this unit and all its
ancestors are below their minimum boundaries, this unit's memory
won't be reclaimed.
Takes a memory size in bytes. If the value is suffixed with K, M,
G or T, the specified memory size is parsed as Kilobytes,
Megabytes, Gigabytes, or Terabytes (with the base 1024),
respectively. Alternatively, a percentage value may be specified,
which is taken relative to the installed physical memory on the
system. If assigned the special value "infinity", all available
memory is protected, which may be useful in order to always
inherit all of the protection afforded by ancestors. This
controls the "memory.min" control group attribute. For details
about this control group attribute, see Memory Interface
Files[6].
This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.
Units may have their children use a default "memory.min" value by
specifying DefaultMemoryMin=, which has the same semantics as
MemoryMin=. This setting does not affect "memory.min" in the unit
itself.
MemoryLow=bytes
Specify the best-effort memory usage protection of the executed
processes in this unit. If the memory usages of this unit and all
its ancestors are below their low boundaries, this unit's memory
won't be reclaimed as long as memory can be reclaimed from
unprotected units.
Takes a memory size in bytes. If the value is suffixed with K, M,
G or T, the specified memory size is parsed as Kilobytes,
Megabytes, Gigabytes, or Terabytes (with the base 1024),
respectively. Alternatively, a percentage value may be specified,
which is taken relative to the installed physical memory on the
system. If assigned the special value "infinity", all available
memory is protected, which may be useful in order to always
inherit all of the protection afforded by ancestors. This
controls the "memory.low" control group attribute. For details
about this control group attribute, see Memory Interface
Files[6].
This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.
Units may have their children use a default "memory.low" value by
specifying DefaultMemoryLow=, which has the same semantics as
MemoryLow=. This setting does not affect "memory.low" in the unit
itself.
MemoryHigh=bytes
Specify the throttling limit on memory usage of the executed
processes in this unit. Memory usage may go above the limit if
unavoidable, but the processes are heavily slowed down and memory
is taken away aggressively in such cases. This is the main
mechanism to control memory usage of a unit.
Takes a memory size in bytes. If the value is suffixed with K, M,
G or T, the specified memory size is parsed as Kilobytes,
Megabytes, Gigabytes, or Terabytes (with the base 1024),
respectively. Alternatively, a percentage value may be specified,
which is taken relative to the installed physical memory on the
system. If assigned the special value "infinity", no memory
throttling is applied. This controls the "memory.high" control
group attribute. For details about this control group attribute,
see Memory Interface Files[6].
This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.
MemoryMax=bytes
Specify the absolute limit on memory usage of the executed
processes in this unit. If memory usage cannot be contained under
the limit, out-of-memory killer is invoked inside the unit. It is
recommended to use MemoryHigh= as the main control mechanism and
use MemoryMax= as the last line of defense.
Takes a memory size in bytes. If the value is suffixed with K, M,
G or T, the specified memory size is parsed as Kilobytes,
Megabytes, Gigabytes, or Terabytes (with the base 1024),
respectively. Alternatively, a percentage value may be specified,
which is taken relative to the installed physical memory on the
system. If assigned the special value "infinity", no memory limit
is applied. This controls the "memory.max" control group
attribute. For details about this control group attribute, see
Memory Interface Files[6].
This setting replaces MemoryLimit=.
MemorySwapMax=bytes
Specify the absolute limit on swap usage of the executed
processes in this unit.
Takes a swap size in bytes. If the value is suffixed with K, M, G
or T, the specified swap size is parsed as Kilobytes, Megabytes,
Gigabytes, or Terabytes (with the base 1024), respectively. If
assigned the special value "infinity", no swap limit is applied.
This controls the "memory.swap.max" control group attribute. For
details about this control group attribute, see Memory Interface
Files[6].
This setting is supported only if the unified control group
hierarchy is used and disables MemoryLimit=.
TasksAccounting=
Turn on task accounting for this unit. Takes a boolean argument.
If enabled, the system manager will keep track of the number of
tasks in the unit. The number of tasks accounted this way
includes both kernel threads and userspace processes, with each
thread counting individually. Note that turning on tasks
accounting for one unit will also implicitly turn it on for all
units contained in the same slice and for all its parent slices
and the units contained therein. The system default for this
setting may be controlled with DefaultTasksAccounting= in
systemd-system.conf(5).
TasksMax=N
Specify the maximum number of tasks that may be created in the
unit. This ensures that the number of tasks accounted for the
unit (see above) stays below a specific limit. This either takes
an absolute number of tasks or a percentage value that is taken
relative to the configured maximum number of tasks on the system.
If assigned the special value "infinity", no tasks limit is
applied. This controls the "pids.max" control group attribute.
For details about this control group attribute, see Process
Number Controller[7].
The system default for this setting may be controlled with
DefaultTasksMax= in systemd-system.conf(5).
IOAccounting=
Turn on Block I/O accounting for this unit, if the unified
control group hierarchy is used on the system. Takes a boolean
argument. Note that turning on block I/O accounting for one unit
will also implicitly turn it on for all units contained in the
same slice and all for its parent slices and the units contained
therein. The system default for this setting may be controlled
with DefaultIOAccounting= in systemd-system.conf(5).
This setting replaces BlockIOAccounting= and disables settings
prefixed with BlockIO or StartupBlockIO.
IOWeight=weight, StartupIOWeight=weight
Set the default overall block I/O weight for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a single weight value (between 1 and 10000) to set
the default block I/O weight. This controls the "io.weight"
control group attribute, which defaults to 100. For details about
this control group attribute, see IO Interface Files[8]. The
available I/O bandwidth is split up among all units within one
slice relative to their block I/O weight.
While StartupIOWeight= only applies to the startup phase of the
system, IOWeight= applies to the later runtime of the system, and
if the former is not set also to the startup phase. This allows
prioritizing specific services at boot-up differently than during
runtime.
These settings replace BlockIOWeight= and StartupBlockIOWeight=
and disable settings prefixed with BlockIO or StartupBlockIO.
IODeviceWeight=device weight
Set the per-device overall block I/O weight for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a space-separated pair of a file path and a weight
value to specify the device specific weight value, between 1 and
10000. (Example: "/dev/sda 1000"). The file path may be specified
as path to a block device node or as any other file, in which
case the backing block device of the file system of the file is
determined. This controls the "io.weight" control group
attribute, which defaults to 100. Use this option multiple times
to set weights for multiple devices. For details about this
control group attribute, see IO Interface Files[8].
This setting replaces BlockIODeviceWeight= and disables settings
prefixed with BlockIO or StartupBlockIO.
The specified device node should reference a block device that
has an I/O scheduler associated, i.e. should not refer to
partition or loopback block devices, but to the originating,
physical device. When a path to a regular file or directory is
specified it is attempted to discover the correct originating
device backing the file system of the specified path. This works
correctly only for simpler cases, where the file system is
directly placed on a partition or physical block device, or where
simple 1:1 encryption using dm-crypt/LUKS is used. This discovery
does not cover complex storage and in particular RAID and volume
management storage devices.
IOReadBandwidthMax=device bytes, IOWriteBandwidthMax=device bytes
Set the per-device overall block I/O bandwidth maximum limit for
the executed processes, if the unified control group hierarchy is
used on the system. This limit is not work-conserving and the
executed processes are not allowed to use more even if the device
has idle capacity. Takes a space-separated pair of a file path
and a bandwidth value (in bytes per second) to specify the device
specific bandwidth. The file path may be a path to a block device
node, or as any other file in which case the backing block device
of the file system of the file is used. If the bandwidth is
suffixed with K, M, G, or T, the specified bandwidth is parsed as
Kilobytes, Megabytes, Gigabytes, or Terabytes, respectively, to
the base of 1000. (Example:
"/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This
controls the "io.max" control group attributes. Use this option
multiple times to set bandwidth limits for multiple devices. For
details about this control group attribute, see IO Interface
Files[8].
These settings replace BlockIOReadBandwidth= and
BlockIOWriteBandwidth= and disable settings prefixed with BlockIO
or StartupBlockIO.
Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.
IOReadIOPSMax=device IOPS, IOWriteIOPSMax=device IOPS
Set the per-device overall block I/O IOs-Per-Second maximum limit
for the executed processes, if the unified control group
hierarchy is used on the system. This limit is not
work-conserving and the executed processes are not allowed to use
more even if the device has idle capacity. Takes a
space-separated pair of a file path and an IOPS value to specify
the device specific IOPS. The file path may be a path to a block
device node, or as any other file in which case the backing block
device of the file system of the file is used. If the IOPS is
suffixed with K, M, G, or T, the specified IOPS is parsed as
KiloIOPS, MegaIOPS, GigaIOPS, or TeraIOPS, respectively, to the
base of 1000. (Example:
"/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 1K"). This
controls the "io.max" control group attributes. Use this option
multiple times to set IOPS limits for multiple devices. For
details about this control group attribute, see IO Interface
Files[8].
These settings are supported only if the unified control group
hierarchy is used and disable settings prefixed with BlockIO or
StartupBlockIO.
Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.
IODeviceLatencyTargetSec=device target
Set the per-device average target I/O latency for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a file path and a timespan separated by a space to
specify the device specific latency target. (Example: "/dev/sda
25ms"). The file path may be specified as path to a block device
node or as any other file, in which case the backing block device
of the file system of the file is determined. This controls the
"io.latency" control group attribute. Use this option multiple
times to set latency target for multiple devices. For details
about this control group attribute, see IO Interface Files[8].
Implies "IOAccounting=yes".
These settings are supported only if the unified control group
hierarchy is used.
Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.
IPAccounting=
Takes a boolean argument. If true, turns on IPv4 and IPv6 network
traffic accounting for packets sent or received by the unit. When
this option is turned on, all IPv4 and IPv6 sockets created by
any process of the unit are accounted for.
When this option is used in socket units, it applies to all IPv4
and IPv6 sockets associated with it (including both listening and
connection sockets where this applies). Note that for
socket-activated services, this configuration setting and the
accounting data of the service unit and the socket unit are kept
separate, and displayed separately. No propagation of the setting
and the collected statistics is done, in either direction.
Moreover, any traffic sent or received on any of the socket
unit's sockets is accounted to the socket unit — and never to the
service unit it might have activated, even if the socket is used
by it.
The system default for this setting may be controlled with
DefaultIPAccounting= in systemd-system.conf(5).
IPAddressAllow=ADDRESS[/PREFIXLENGTH]...,
IPAddressDeny=ADDRESS[/PREFIXLENGTH]...
Turn on network traffic filtering for IP packets sent and
received over AF_INET and AF_INET6 sockets. Both directives take
a space separated list of IPv4 or IPv6 addresses, each optionally
suffixed with an address prefix length in bits after a "/"
character. If the suffix is omitted, the address is considered a
host address, i.e. the filter covers the whole address (32 bits
for IPv4, 128 bits for IPv6).
The access lists configured with this option are applied to all
sockets created by processes of this unit (or in the case of
socket units, associated with it). The lists are implicitly
combined with any lists configured for any of the parent slice
units this unit might be a member of. By default both access
lists are empty. Both ingress and egress traffic is filtered by
these settings. In case of ingress traffic the source IP address
is checked against these access lists, in case of egress traffic
the destination IP address is checked. The following rules are
applied in turn:
· Access is granted when the checked IP address matches an
entry in the IPAddressAllow= list.
· Otherwise, access is denied when the checked IP address
matches an entry in the IPAddressDeny= list.
· Otherwise, access is granted.
In order to implement an allow-listing IP firewall, it is
recommended to use a IPAddressDeny=any setting on an upper-level
slice unit (such as the root slice -.slice or the slice
containing all system services system.slice – see
systemd.special(7) for details on these slice units), plus
individual per-service IPAddressAllow= lines permitting network
access to relevant services, and only them.
Note that for socket-activated services, the IP access list
configured on the socket unit applies to all sockets associated
with it directly, but not to any sockets created by the
ultimately activated services for it. Conversely, the IP access
list configured for the service is not applied to any sockets
passed into the service via socket activation. Thus, it is
usually a good idea to replicate the IP access lists on both the
socket and the service unit. Nevertheless, it may make sense to
maintain one list more open and the other one more restricted,
depending on the usecase.
If these settings are used multiple times in the same unit the
specified lists are combined. If an empty string is assigned to
these settings the specific access list is reset and all previous
settings undone.
In place of explicit IPv4 or IPv6 address and prefix length
specifications a small set of symbolic names may be used. The
following names are defined:
Table 1. Special address/network names
┌──────────────┬─────────────────────┬─────────────────────┐
│Symbolic Name │ Definition │ Meaning │
├──────────────┼─────────────────────┼─────────────────────┤
│any │ 0.0.0.0/0 ::/0 │ Any host │
├──────────────┼─────────────────────┼─────────────────────┤
│localhost │ 127.0.0.0/8 ::1/128 │ All addresses on │
│ │ │ the local loopback │
├──────────────┼─────────────────────┼─────────────────────┤
│link-local │ 169.254.0.0/16 │ All link-local IP │
│ │ fe80::/64 │ addresses │
├──────────────┼─────────────────────┼─────────────────────┤
│multicast │ 224.0.0.0/4 │ All IP multicasting │
│ │ ff00::/8 │ addresses │
└──────────────┴─────────────────────┴─────────────────────┘
Note that these settings might not be supported on some systems
(for example if eBPF control group support is not enabled in the
underlying kernel or container manager). These settings will have
no effect in that case. If compatibility with such systems is
desired it is hence recommended to not exclusively rely on them
for IP security.
IPIngressFilterPath=BPF_FS_PROGRAM_PATH,
IPEgressFilterPath=BPF_FS_PROGRAM_PATH
Add custom network traffic filters implemented as BPF programs,
applying to all IP packets sent and received over AF_INET and
AF_INET6 sockets. Takes an absolute path to a pinned BPF program
in the BPF virtual filesystem (/sys/fs/bpf/).
The filters configured with this option are applied to all
sockets created by processes of this unit (or in the case of
socket units, associated with it). The filters are loaded in
addition to filters any of the parent slice units this unit might
be a member of as well as any IPAddressAllow= and IPAddressDeny=
filters in any of these units. By default there are no filters
specified.
If these settings are used multiple times in the same unit all
the specified programs are attached. If an empty string is
assigned to these settings the program list is reset and all
previous specified programs ignored.
Note that for socket-activated services, the IP filter programs
configured on the socket unit apply to all sockets associated
with it directly, but not to any sockets created by the
ultimately activated services for it. Conversely, the IP filter
programs configured for the service are not applied to any
sockets passed into the service via socket activation. Thus, it
is usually a good idea, to replicate the IP filter programs on
both the socket and the service unit, however it often makes
sense to maintain one configuration more open and the other one
more restricted, depending on the usecase.
Note that these settings might not be supported on some systems
(for example if eBPF control group support is not enabled in the
underlying kernel or container manager). These settings will fail
the service in that case. If compatibility with such systems is
desired it is hence recommended to attach your filter manually
(requires Delegate=yes) instead of using this setting.
DeviceAllow=
Control access to specific device nodes by the executed
processes. Takes two space-separated strings: a device node
specifier followed by a combination of r, w, m to control
reading, writing, or creation of the specific device node(s) by
the unit (mknod), respectively. On cgroup-v1 this controls the
"devices.allow" control group attribute. For details about this
control group attribute, see Device Whitelist Controller[9]. In
the unified cgroup hierarchy this functionality is implemented
using eBPF filtering.
The device node specifier is either a path to a device node in
the file system, starting with /dev/, or a string starting with
either "char-" or "block-" followed by a device group name, as
listed in /proc/devices. The latter is useful to allow-list all
current and future devices belonging to a specific device group
at once. The device group is matched according to filename
globbing rules, you may hence use the "*" and "?" wildcards.
(Note that such globbing wildcards are not available for device
node path specifications!) In order to match device nodes by
numeric major/minor, use device node paths in the /dev/char/ and
/dev/block/ directories. However, matching devices by major/minor
is generally not recommended as assignments are neither stable
nor portable between systems or different kernel versions.
Examples: /dev/sda5 is a path to a device node, referring to an
ATA or SCSI block device. "char-pts" and "char-alsa" are
specifiers for all pseudo TTYs and all ALSA sound devices,
respectively. "char-cpu/*" is a specifier matching all CPU
related device groups.
Note that allow lists defined this way should only reference
device groups which are resolvable at the time the unit is
started. Any device groups not resolvable then are not added to
the device allow list. In order to work around this limitation,
consider extending service units with a pair of
After=modprobe@xyz.service and Wants=modprobe@xyz.service lines
that load the necessary kernel module implementing the device
group if missing. Example:
...
[Unit]
Wants=modprobe@loop.service
After=modprobe@loop.service
[Service]
DeviceAllow=block-loop
DeviceAllow=/dev/loop-control
...
DevicePolicy=auto|closed|strict
Control the policy for allowing device access:
strict
means to only allow types of access that are explicitly
specified.
closed
in addition, allows access to standard pseudo devices
including /dev/null, /dev/zero, /dev/full, /dev/random, and
/dev/urandom.
auto
in addition, allows access to all devices if no explicit
DeviceAllow= is present. This is the default.
Slice=
The name of the slice unit to place the unit in. Defaults to
system.slice for all non-instantiated units of all unit types
(except for slice units themselves see below). Instance units are
by default placed in a subslice of system.slice that is named
after the template name.
This option may be used to arrange systemd units in a hierarchy
of slices each of which might have resource settings applied.
For units of type slice, the only accepted value for this setting
is the parent slice. Since the name of a slice unit implies the
parent slice, it is hence redundant to ever set this parameter
directly for slice units.
Special care should be taken when relying on the default slice
assignment in templated service units that have
DefaultDependencies=no set, see systemd.service(5), section
"Default Dependencies" for details.
Delegate=
Turns on delegation of further resource control partitioning to
processes of the unit. Units where this is enabled may create and
manage their own private subhierarchy of control groups below the
control group of the unit itself. For unprivileged services (i.e.
those using the User= setting) the unit's control group will be
made accessible to the relevant user. When enabled the service
manager will refrain from manipulating control groups or moving
processes below the unit's control group, so that a clear concept
of ownership is established: the control group tree above the
unit's control group (i.e. towards the root control group) is
owned and managed by the service manager of the host, while the
control group tree below the unit's control group is owned and
managed by the unit itself. Takes either a boolean argument or a
list of control group controller names. If true, delegation is
turned on, and all supported controllers are enabled for the
unit, making them available to the unit's processes for
management. If false, delegation is turned off entirely (and no
additional controllers are enabled). If set to a list of
controllers, delegation is turned on, and the specified
controllers are enabled for the unit. Note that additional
controllers than the ones specified might be made available as
well, depending on configuration of the containing slice unit or
other units contained in it. Note that assigning the empty string
will enable delegation, but reset the list of controllers, all
assignments prior to this will have no effect. Defaults to false.
Note that controller delegation to less privileged code is only
safe on the unified control group hierarchy. Accordingly, access
to the specified controllers will not be granted to unprivileged
services on the legacy hierarchy, even when requested.
The following controller names may be specified: cpu, cpuacct,
cpuset, io, blkio, memory, devices, pids, bpf-firewall, and
bpf-devices.
Not all of these controllers are available on all kernels
however, and some are specific to the unified hierarchy while
others are specific to the legacy hierarchy. Also note that the
kernel might support further controllers, which aren't covered
here yet as delegation is either not supported at all for them or
not defined cleanly.
For further details on the delegation model consult Control Group
APIs and Delegation[10].
DisableControllers=
Disables controllers from being enabled for a unit's children. If
a controller listed is already in use in its subtree, the
controller will be removed from the subtree. This can be used to
avoid child units being able to implicitly or explicitly enable a
controller. Defaults to not disabling any controllers.
It may not be possible to successfully disable a controller if
the unit or any child of the unit in question delegates
controllers to its children, as any delegated subtree of the
cgroup hierarchy is unmanaged by systemd.
Multiple controllers may be specified, separated by spaces. You
may also pass DisableControllers= multiple times, in which case
each new instance adds another controller to disable. Passing
DisableControllers= by itself with no controller name present
resets the disabled controller list.
The following controller names may be specified: cpu, cpuacct,
cpuset, io, blkio, memory, devices, pids, bpf-firewall, and
bpf-devices.
The following options are deprecated. Use the indicated superseding
options instead:
CPUShares=weight, StartupCPUShares=weight
Assign the specified CPU time share weight to the processes
executed. These options take an integer value and control the
"cpu.shares" control group attribute. The allowed range is 2 to
262144. Defaults to 1024. For details about this control group
attribute, see CFS Scheduler[4]. The available CPU time is split
up among all units within one slice relative to their CPU time
share weight.
While StartupCPUShares= only applies to the startup phase of the
system, CPUShares= applies to normal runtime of the system, and
if the former is not set also to the startup phase. Using
StartupCPUShares= allows prioritizing specific services at
boot-up differently than during normal runtime.
Implies "CPUAccounting=yes".
These settings are deprecated. Use CPUWeight= and
StartupCPUWeight= instead.
MemoryLimit=bytes
Specify the limit on maximum memory usage of the executed
processes. The limit specifies how much process and kernel memory
can be used by tasks in this unit. Takes a memory size in bytes.
If the value is suffixed with K, M, G or T, the specified memory
size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes
(with the base 1024), respectively. Alternatively, a percentage
value may be specified, which is taken relative to the installed
physical memory on the system. If assigned the special value
"infinity", no memory limit is applied. This controls the
"memory.limit_in_bytes" control group attribute. For details
about this control group attribute, see Memory Resource
Controller[11].
Implies "MemoryAccounting=yes".
This setting is deprecated. Use MemoryMax= instead.
BlockIOAccounting=
Turn on Block I/O accounting for this unit, if the legacy control
group hierarchy is used on the system. Takes a boolean argument.
Note that turning on block I/O accounting for one unit will also
implicitly turn it on for all units contained in the same slice
and all for its parent slices and the units contained therein.
The system default for this setting may be controlled with
DefaultBlockIOAccounting= in systemd-system.conf(5).
This setting is deprecated. Use IOAccounting= instead.
BlockIOWeight=weight, StartupBlockIOWeight=weight
Set the default overall block I/O weight for the executed
processes, if the legacy control group hierarchy is used on the
system. Takes a single weight value (between 10 and 1000) to set
the default block I/O weight. This controls the "blkio.weight"
control group attribute, which defaults to 500. For details about
this control group attribute, see Block IO Controller[12]. The
available I/O bandwidth is split up among all units within one
slice relative to their block I/O weight.
While StartupBlockIOWeight= only applies to the startup phase of
the system, BlockIOWeight= applies to the later runtime of the
system, and if the former is not set also to the startup phase.
This allows prioritizing specific services at boot-up differently
than during runtime.
Implies "BlockIOAccounting=yes".
These settings are deprecated. Use IOWeight= and StartupIOWeight=
instead.
BlockIODeviceWeight=device weight
Set the per-device overall block I/O weight for the executed
processes, if the legacy control group hierarchy is used on the
system. Takes a space-separated pair of a file path and a weight
value to specify the device specific weight value, between 10 and
1000. (Example: "/dev/sda 500"). The file path may be specified
as path to a block device node or as any other file, in which
case the backing block device of the file system of the file is
determined. This controls the "blkio.weight_device" control group
attribute, which defaults to 1000. Use this option multiple times
to set weights for multiple devices. For details about this
control group attribute, see Block IO Controller[12].
Implies "BlockIOAccounting=yes".
This setting is deprecated. Use IODeviceWeight= instead.
BlockIOReadBandwidth=device bytes, BlockIOWriteBandwidth=device bytes
Set the per-device overall block I/O bandwidth limit for the
executed processes, if the legacy control group hierarchy is used
on the system. Takes a space-separated pair of a file path and a
bandwidth value (in bytes per second) to specify the device
specific bandwidth. The file path may be a path to a block device
node, or as any other file in which case the backing block device
of the file system of the file is used. If the bandwidth is
suffixed with K, M, G, or T, the specified bandwidth is parsed as
Kilobytes, Megabytes, Gigabytes, or Terabytes, respectively, to
the base of 1000. (Example:
"/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This
controls the "blkio.throttle.read_bps_device" and
"blkio.throttle.write_bps_device" control group attributes. Use
this option multiple times to set bandwidth limits for multiple
devices. For details about these control group attributes, see
Block IO Controller[12].
Implies "BlockIOAccounting=yes".
These settings are deprecated. Use IOReadBandwidthMax= and
IOWriteBandwidthMax= instead.
systemd(1), systemd-system.conf(5), systemd.unit(5),
systemd.service(5), systemd.slice(5), systemd.scope(5),
systemd.socket(5), systemd.mount(5), systemd.swap(5),
systemd.exec(5), systemd.directives(7), systemd.special(7), The
documentation for control groups and specific controllers in the
Linux kernel: Control Groups v2[2].
1. New Control Group Interfaces
https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/
2. Control Groups v2
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html
3. Control Groups version 1
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/
4. CFS Scheduler
https://www.kernel.org/doc/html/latest/scheduler/sched-design-CFS.html
5. sched-bwc.txt
https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
6. Memory Interface Files
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files
7. Process Number Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/pids.html
8. IO Interface Files
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#io-interface-files
9. Device Whitelist Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/devices.html
10. Control Group APIs and Delegation
https://systemd.io/CGROUP_DELEGATION
11. Memory Resource Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/memory.html
12. Block IO Controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/blkio-controller.html
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⟨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
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