NAME | SYNOPSIS | DESCRIPTION | AUTOMATIC DEPENDENCIES | UNIFIED AND LEGACY CONTROL GROUP HIERARCHIES | 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
       Control Groups 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.

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

AUTOMATIC DEPENDENCIES         top

       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 cgroup-v2.txt[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
           Due to the lack of consensus in the kernel community, the CPU
           controller support on the unified cgroup hierarchy requires
           out-of-tree kernel patches. See cgroup-v2-cpu.txt[3].

           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 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. If all settings of a unit for a given
       resource type are for the other hierarchy type, the settings are
       translated and applied. If there are any valid settings for the
       hierarchy in use, all translations are disabled for the resource
       type. Mixing the two types of settings on a unit can lead to
       confusing results.

       Legacy control group hierarchy (see cgroups.txt[4]), 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 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 cgroup-v2.txt[2] and sched-design-CFS.txt[5]. 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.

           Implies "CPUAccounting=true".

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

       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 sched-design-CFS.txt[5]. 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=true".

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

       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 cgroup-v2.txt[2] and
           sched-design-CFS.txt[5].

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

           Implies "CPUAccounting=true".

           This setting is supported on both unified and legacy control
           group hierarchies.

       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).

       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. This controls the "memory.low" control group attribute.
           For details about this control group attribute, see
           cgroup-v2.txt[2].

           Implies "MemoryAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used.

       MemoryHigh=bytes
           Specify the high 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 limit
           is applied. This controls the "memory.high" control group
           attribute. For details about this control group attribute, see
           cgroup-v2.txt[2].

           Implies "MemoryAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used.

       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
           cgroup-v2.txt[2].

           Implies "MemoryAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used. Use MemoryLimit= on systems using the legacy
           control group hierarchy.

       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 cgroup-v2.txt[2].

           Implies "MemoryAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used.

       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.txt[6].

           Implies "MemoryAccounting=true".

           This setting is supported only if the legacy control group
           hierarchy is used. Use MemoryMax= on systems using the unified
           control group hierarchy.

       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 pids.txt[7].

           Implies "TasksAccounting=true". 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 is supported only if the unified control group
           hierarchy is used. Use BlockIOAccounting= on systems using the
           legacy control group hierarchy.

       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 cgroup-v2.txt[2]. 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.

           Implies "IOAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used. Use BlockIOWeight= and StartupBlockIOWeight=
           on systems using the legacy control group hierarchy.

       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 cgroup-v2.txt[2].

           Implies "IOAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used. Use BlockIODeviceWeight= on systems using the
           legacy control group hierarchy.

       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 cgroup-v2.txt[2].

           Implies "IOAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used. Use BlockIOAccounting= on systems using the
           legacy control group hierarchy.

       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 cgroup-v2.txt[2].

           Implies "IOAccounting=true".

           This setting is supported only if the unified control group
           hierarchy is used.

       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 supported only if the legacy control group
           hierarchy is used. Use IOAccounting= on systems using the unified
           control group hierarchy.

       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 blkio-controller.txt[8]. 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=true".

           This setting is supported only if the legacy control group
           hierarchy is used. Use IOWeight= and StartupIOWeight= on systems
           using the unified control group hierarchy.

       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 blkio-controller.txt[8].

           Implies "BlockIOAccounting=true".

           This setting is supported only if the legacy control group
           hierarchy is used. Use IODeviceWeight= on systems using the
           unified control group hierarchy.

       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
           blkio-controller.txt[8].

           Implies "BlockIOAccounting=true".

           This setting is supported only if the legacy control group
           hierarchy is used. Use IOReadBandwidthMax= and
           IOWriteBandwidthMax= on systems using the unified control group
           hierarchy.

       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. This controls the "devices.allow"
           and "devices.deny" control group attributes. For details about
           these control group attributes, see devices.txt[9].

           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 file name
           globbing rules, you may hence use the "*" and "?"  wildcards.
           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.

       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
           "Automatic Dependencies" for details.

       Delegate=
           Turns on delegation of further resource control partitioning to
           processes of the unit. For unprivileged services (i.e. those
           using the User= setting), this allows processes to create a
           subhierarchy beneath its control group path. For privileged
           services and scopes, this ensures the processes will have all
           control group controllers enabled.

SEE ALSO         top

       systemd(1), systemd.unit(5), systemd.service(5), systemd.slice(5),
       systemd.scope(5), systemd.socket(5), systemd.mount(5),
       systemd.swap(5), systemd.directives(7), systemd.special(7), The
       documentation for control groups and specific controllers in the
       Linux kernel: cgroups.txt[4], cpuacct.txt[10], memory.txt[6],
       blkio-controller.txt[8].

NOTES         top

        1. New Control Group Interfaces
           http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/

        2. cgroup-v2.txt
           https://www.kernel.org/doc/Documentation/cgroup-v2.txt

        3. cgroup-v2-cpu.txt
           https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/tree/Documentation/cgroup-v2-cpu.txt?h=cgroup-v2-cpu

        4. cgroups.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt

        5. sched-design-CFS.txt
           https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt

        6. memory.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt

        7. pids.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/pids.txt

        8. blkio-controller.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/blkio-controller.txt

        9. devices.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/devices.txt

       10. cpuacct.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/cpuacct.txt

COLOPHON         top

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       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a bug
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       COLOPHON (which is not part of the original manual page), send a mail
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systemd 231                                      SYSTEMD.RESOURCE-CONTROL(5)