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

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)

NAME         top

       systemd.resource-control - Resource control unit settings

SYNOPSIS         top

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

DESCRIPTION         top

       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.

IMPLICIT DEPENDENCIES         top

       The following dependencies are implicitly added:

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

UNIFIED AND LEGACY CONTROL GROUP HIERARCHIES         top

       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).

OPTIONS         top

       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 a whitelisting 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_PROGRAMM_PATH,
       IPEgressFilterPath=BPF_FS_PROGRAMM_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 whitelist 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 whitelists 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 whitelist. 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.

DEPRECATED OPTIONS         top

       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.

SEE ALSO         top

       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].

NOTES         top

        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

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a bug
       report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2020-06-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-09.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

systemd 245                                      SYSTEMD.RESOURCE-CONTROL(5)

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