Provided by: systemd_256.4-2ubuntu1_amd64 bug

NAME

       systemd.resource-control - Resource control unit settings

SYNOPSIS

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

DESCRIPTION

       Unit configuration files for services, slices, scopes, sockets, mount points, and swap
       devices share a subset of configuration options for resource control of spawned processes.
       Internally, this relies on the Linux Control Groups (cgroups) kernel concept for
       organizing processes in a hierarchical tree of named groups for the purpose of resource
       management.

       This man page lists the configuration options shared by those six unit types. See
       systemd.unit(5) for the common options of all unit configuration files, and
       systemd.slice(5), systemd.scope(5), systemd.service(5), systemd.socket(5),
       systemd.mount(5), and systemd.swap(5) for more information on the specific unit
       configuration files. The resource control configuration options are configured in the
       [Slice], [Scope], [Service], [Socket], [Mount], or [Swap] sections, depending on the unit
       type.

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

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

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

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

       Example 1. Enabling and disabling controllers

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

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

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

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

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

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

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

IMPLICIT DEPENDENCIES

       The following dependencies are implicitly added:

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

OPTIONS

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

   CPU Accounting and Control
       CPUAccounting=
           Turn on CPU usage accounting for this unit. Takes a boolean argument. Note that
           turning on CPU accounting for one unit will also implicitly turn it on for all units
           contained in the same slice and for all its parent slices and the units contained
           therein. The system default for this setting may be controlled with
           DefaultCPUAccounting= in systemd-system.conf(5).

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

           Added in version 208.

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

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

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

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

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

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

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

           Added in version 232.

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

           Assign the specified CPU time quota to the processes executed. Takes a percentage
           value, suffixed with "%". The percentage specifies how much CPU time the unit shall
           get at maximum, relative to the total CPU time available on one CPU. Use values > 100%
           for allotting CPU time on more than one CPU. This controls the "cpu.max" attribute on
           the unified control group hierarchy and "cpu.cfs_quota_us" on legacy. For details
           about these control group attributes, see Control Groups v2[2] and CFS Bandwidth
           Control[4]. Setting CPUQuota= to an empty value unsets the quota.

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

           Added in version 213.

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

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

           This controls the second field of "cpu.max" attribute on the unified control group
           hierarchy and "cpu.cfs_period_us" on legacy. For details about these control group
           attributes, see Control Groups v2[2] and CFS Scheduler[3].

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

           Added in version 242.

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

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

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

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

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

           Added in version 244.

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

           Turn on process and kernel memory accounting for this unit. Takes a boolean argument.
           Note that turning on memory accounting for one unit will also implicitly turn it on
           for all units contained in the same slice and for all its parent slices and the units
           contained therein. The system default for this setting may be controlled with
           DefaultMemoryAccounting= in systemd-system.conf(5).

           Added in version 208.

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

           Specify the memory usage protection of the executed processes in this unit. When
           reclaiming memory, the unit is treated as if it was using less memory resulting in
           memory to be preferentially reclaimed from unprotected units. Using MemoryLow= results
           in a weaker protection where memory may still be reclaimed to avoid invoking the OOM
           killer in case there is no other reclaimable memory.

           For a protection to be effective, it is generally required to set a corresponding
           allocation on all ancestors, which is then distributed between children (with the
           exception of the root slice). Any MemoryMin= or MemoryLow= allocation that is not
           explicitly distributed to specific children is used to create a shared protection for
           all children. As this is a shared protection, the children will freely compete for the
           memory.

           Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the
           specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with
           the base 1024), respectively. Alternatively, a percentage value may be specified,
           which is taken relative to the installed physical memory on the system. If assigned
           the special value "infinity", all available memory is protected, which may be useful
           in order to always inherit all of the protection afforded by ancestors. This controls
           the "memory.min" or "memory.low" control group attribute. For details about this
           control group attribute, see Memory Interface Files[5].

           Units may have their children use a default "memory.min" or "memory.low" value by
           specifying DefaultMemoryMin= or DefaultMemoryLow=, which has the same semantics as
           MemoryMin= and MemoryLow=, or DefaultStartupMemoryLow= which has the same semantics as
           StartupMemoryLow=. This setting does not affect "memory.min" or "memory.low" in the
           unit itself. Using it to set a default child allocation is only useful on kernels
           older than 5.7, which do not support the "memory_recursiveprot" cgroup2 mount option.

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

           Added in version 240.

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

           Specify the throttling limit on memory usage of the executed processes in this unit.
           Memory usage may go above the limit if unavoidable, but the processes are heavily
           slowed down and memory is taken away aggressively in such cases. This is the main
           mechanism to control memory usage of a unit.

           Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the
           specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with
           the base 1024), respectively. Alternatively, a percentage value may be specified,
           which is taken relative to the installed physical memory on the system. If assigned
           the special value "infinity", no memory throttling is applied. This controls the
           "memory.high" control group attribute. For details about this control group attribute,
           see Memory Interface Files[5]. The effective configuration is reported as
           EffectiveMemoryHigh= (see also EffectiveMemoryMax=).

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

           Added in version 231.

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

           Specify the absolute limit on memory usage of the executed processes in this unit. If
           memory usage cannot be contained under the limit, out-of-memory killer is invoked
           inside the unit. It is recommended to use MemoryHigh= as the main control mechanism
           and use MemoryMax= as the last line of defense.

           Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the
           specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with
           the base 1024), respectively. Alternatively, a percentage value may be specified,
           which is taken relative to the installed physical memory on the system. If assigned
           the special value "infinity", no memory limit is applied. This controls the
           "memory.max" control group attribute. For details about this control group attribute,
           see Memory Interface Files[5]. The effective configuration is reported as
           EffectiveMemoryMax= (the value is the most stringent limit of the unit and parent
           slices and it is capped by physical memory).

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

           Added in version 231.

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

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

           Takes a swap size in bytes. If the value is suffixed with K, M, G or T, the specified
           swap size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base
           1024), respectively. 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= doesn't guarantee that all
           of the memory NUMA nodes will be used by the processes as it may be limited by parent
           units. The effective configuration is reported as EffectiveMemoryNodes=.

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

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

           Added in version 244.

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

           Turn on task accounting for this unit. Takes a boolean argument. If enabled, the
           kernel will keep track of the total number of tasks in the unit and its children. This
           number includes both kernel threads and userspace processes, with each thread counted
           individually. Note that turning on tasks accounting for one unit will also implicitly
           turn it on for all units contained in the same slice and for all its parent slices and
           the units contained therein. The system default for this setting may be controlled
           with DefaultTasksAccounting= in systemd-system.conf(5).

           Added in version 227.

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

           Specify the maximum number of tasks that may be created in the unit. This ensures that
           the number of tasks accounted for the unit (see above) stays below a specific limit.
           This either takes an absolute number of tasks or a percentage value that is taken
           relative to the configured maximum number of tasks on the system. If assigned the
           special value "infinity", no tasks limit is applied. This controls the "pids.max"
           control group attribute. For details about this control group attribute, the pids
           controller[7]. The effective configuration is reported as EffectiveTasksMax=.

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

           Added in version 227.

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

           Turn on Block I/O accounting for this unit, if the unified control group hierarchy is
           used on the system. Takes a boolean argument. Note that turning on block I/O
           accounting for one unit will also implicitly turn it on for all units contained in the
           same slice and all for its parent slices and the units contained therein. The system
           default for this setting may be controlled with DefaultIOAccounting= in systemd-
           system.conf(5).

           Added in version 230.

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

           Set the default overall block I/O weight for the executed processes, if the unified
           control group hierarchy is used on the system. Takes a single weight value (between 1
           and 10000) to set the default block I/O weight. This controls the "io.weight" control
           group attribute, which defaults to 100. For details about this control group
           attribute, see IO Interface Files[8]. The available I/O bandwidth is split up among
           all units within one slice relative to their block I/O weight. A higher weight means
           more I/O bandwidth, a lower weight means less.

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

           Added in version 230.

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

           Set the per-device overall block I/O weight for the executed processes, if the unified
           control group hierarchy is used on the system. Takes a space-separated pair of a file
           path and a weight value to specify the device specific weight value, between 1 and
           10000. (Example: "/dev/sda 1000"). The file path may be specified as path to a block
           device node or as any other file, in which case the backing block device of the file
           system of the file is determined. This controls the "io.weight" control group
           attribute, which defaults to 100. Use this option multiple times to set weights for
           multiple devices. For details about this control group attribute, see IO Interface
           Files[8].

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

           Added in version 230.

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

           Set the per-device overall block I/O bandwidth maximum limit for the executed
           processes, if the unified control group hierarchy is used on the system. This limit is
           not work-conserving and the executed processes are not allowed to use more even if the
           device has idle capacity. Takes a space-separated pair of a file path and a bandwidth
           value (in bytes per second) to specify the device specific bandwidth. The file path
           may be a path to a block device node, or as any other file in which case the backing
           block device of the file system of the file is used. If the bandwidth is suffixed with
           K, M, G, or T, the specified bandwidth is parsed as Kilobytes, Megabytes, Gigabytes,
           or Terabytes, respectively, to the base of 1000. (Example:
           "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This controls the "io.max"
           control group attributes. Use this option multiple times to set bandwidth limits for
           multiple devices. For details about this control group attribute, see IO Interface
           Files[8].

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

           Added in version 230.

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

           Set the per-device overall block I/O IOs-Per-Second maximum limit for the executed
           processes, if the unified control group hierarchy is used on the system. This limit is
           not work-conserving and the executed processes are not allowed to use more even if the
           device has idle capacity. Takes a space-separated pair of a file path and an IOPS
           value to specify the device specific IOPS. The file path may be a path to a block
           device node, or as any other file in which case the backing block device of the file
           system of the file is used. If the IOPS is suffixed with K, M, G, or T, the specified
           IOPS is parsed as KiloIOPS, MegaIOPS, GigaIOPS, or TeraIOPS, respectively, to the base
           of 1000. (Example: "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 1K"). This
           controls the "io.max" control group attributes. Use this option multiple times to set
           IOPS limits for multiple devices. For details about this control group attribute, see
           IO Interface Files[8].

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

           Added in version 230.

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

           Set the per-device average target I/O latency for the executed processes, if the
           unified control group hierarchy is used on the system. Takes a file path and a
           timespan separated by a space to specify the device specific latency target. (Example:
           "/dev/sda 25ms"). The file path may be specified as path to a block device node or as
           any other file, in which case the backing block device of the file system of the file
           is determined. This controls the "io.latency" control group attribute. Use this option
           multiple times to set latency target for multiple devices. For details about this
           control group attribute, see IO Interface Files[8].

           Implies "IOAccounting=yes".

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

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

           Added in version 240.

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

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

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

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

           Added in version 235.

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

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

           •   Access is granted when the checked IP address matches an entry in the
               IPAddressAllow= list.

           •   Otherwise, access is denied when the checked IP address matches an entry in the
               IPAddressDeny= list.

           •   Otherwise, access is granted.

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

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

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

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

           Table 1. Special address/network names
           ┌──────────────┬──────────────────────────┬──────────────────────┐
           │Symbolic NameDefinitionMeaning              │
           ├──────────────┼──────────────────────────┼──────────────────────┤
           │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 fe80::/64 │ All link-local IP    │
           │              │                          │ 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 may defined that restrict which addresses a socket
           may be bound to.

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

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

           address-family := { ipv4 | ipv6 }

           transport-protocol := { tcp | udp }

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

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

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

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

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

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

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

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

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

           •   Otherwise, binding is allowed.

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

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

           Examples:

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

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

           Added in version 249.

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

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

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

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

           Example 1: allow-list

               RestrictNetworkInterfaces=eth1
               RestrictNetworkInterfaces=eth2

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

           Example 2: deny-list

               RestrictNetworkInterfaces=~eth1 eth2

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

           Example 3: mixed

               RestrictNetworkInterfaces=eth1 eth2
               RestrictNetworkInterfaces=~eth1

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

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

           Added in version 250.

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

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

           Table 2. Defined source type values
           ┌────────────┬──────────────────┬────────────────────────┐
           │Source typeDescriptionCorresponding NFT type │
           │            │                  │ name                   │
           ├────────────┼──────────────────┼────────────────────────┤
           │"cgroup"    │ control group ID │ "cgroupsv2"            │
           ├────────────┼──────────────────┼────────────────────────┤
           │"user"      │ user ID          │ "meta skuid"           │
           ├────────────┼──────────────────┼────────────────────────┤
           │"group"     │ group ID         │ "meta skgid"           │
           └────────────┴──────────────────┴────────────────────────┘
           If the firewall rules are reinstalled so that the contents of NFT sets are destroyed,
           command systemctl daemon-reload can be used to refill the sets.

           Example:

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

           Corresponding NFT rules:

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

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

           Added in version 255.

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

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

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

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

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

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

           Added in version 243.

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

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

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

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

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

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

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

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

           Examples:

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

           Added in version 249.

   Device Access
       DeviceAllow=
           Control access to specific device nodes by the executed processes. Takes two
           space-separated strings: a device node specifier followed by a combination of r, w, m
           to control reading, writing, or creation of the specific device nodes by the unit
           (mknod), respectively. This functionality is implemented using eBPF filtering.

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

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

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

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

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

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

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

           Added in version 208.

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

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

               Added in version 208.

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

               Added in version 208.

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

               Added in version 208.

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

           Added in version 208.

   Control Group Management
       Slice=
           The name of the slice unit to place the unit in. Defaults to system.slice for all
           non-instantiated units of all unit types (except for slice units themselves see
           below). Instance units are by default placed in a subslice of system.slice that is
           named after the template name.

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

           For units of type slice, the only accepted value for this setting is the parent slice.
           Since the name of a slice unit implies the parent slice, it is hence redundant to ever
           set this parameter directly for slice units.

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

           Added in version 208.

       Delegate=
           Turns on delegation of further resource control partitioning to processes of the unit.
           Units where this is enabled may create and manage their own private subhierarchy of
           control groups below the control group of the unit itself. For unprivileged services
           (i.e. those using the User= setting) the unit's control group will be made accessible
           to the relevant user.

           When enabled the service manager will refrain from manipulating control groups or
           moving processes below the unit's control group, so that a clear concept of ownership
           is established: the control group tree at the level of the unit's control group and
           above (i.e. towards the root control group) is owned and managed by the service
           manager of the host, while the control group tree below the unit's control group is
           owned and managed by the unit itself.

           Takes either a boolean argument or a (possibly empty) list of control group controller
           names. If true, delegation is turned on, and all supported controllers are enabled for
           the unit, making them available to the unit's processes for management. If false,
           delegation is turned off entirely (and no additional controllers are enabled). If set
           to a list of controllers, delegation is turned on, and the specified controllers are
           enabled for the unit. Assigning the empty string will enable delegation, but reset the
           list of controllers, and all assignments prior to this will have no effect. Note that
           additional controllers other than the ones specified might be made available as well,
           depending on configuration of the containing slice unit or other units contained in
           it. Defaults to false.

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

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

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

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

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

           Added in version 218.

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

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

           Added in version 254.

       DisableControllers=
           Disables controllers from being enabled for a unit's children. If a controller listed
           is already in use in its subtree, the controller will be removed from the subtree.
           This can be used to avoid configuration in child units from being able to implicitly
           or explicitly enable a controller. Defaults to empty.

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

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

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

           Added in version 240.

   Memory Pressure Control
       ManagedOOMSwap=auto|kill, ManagedOOMMemoryPressure=auto|kill
           Specifies how systemd-oomd.service(8) will act on this unit's cgroups. Defaults to
           auto.

           When set to kill, the unit becomes a candidate for monitoring by systemd-oomd. If the
           cgroup passes the limits set by oomd.conf(5) or the unit configuration, systemd-oomd
           will select a descendant cgroup and send SIGKILL to all of the processes under it. You
           can find more details on candidates and kill behavior at systemd-oomd.service(8) and
           oomd.conf(5).

           Setting either of these properties to kill will also result in After= and Wants=
           dependencies on systemd-oomd.service unless DefaultDependencies=no.

           When set to auto, systemd-oomd will not actively use this cgroup's data for monitoring
           and detection. However, if an ancestor cgroup has one of these properties set to kill,
           a unit with auto can still be a candidate for systemd-oomd to terminate.

           Added in version 247.

       ManagedOOMMemoryPressureLimit=
           Overrides the default memory pressure limit set by oomd.conf(5) for this unit
           (cgroup). Takes a percentage value between 0% and 100%, inclusive. This property is
           ignored unless ManagedOOMMemoryPressure=kill. Defaults to 0%, which means to use the
           default set by oomd.conf(5).

           Added in version 247.

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

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

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

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

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

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

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

           Added in version 248.

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

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

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

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

           Added in version 254.

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

           Added in version 254.

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

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

           Added in version 255.

HISTORY

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

           Added in version 252.

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