systemd.resource-control — Resource control unit settings
,
slice
.slice
,
scope
.scope
,
service
.service
,
socket
.socket
,
mount
.mountswap
.swap
Unit configuration files for services, slices, scopes, sockets, mount points, and swap devices share a subset of configuration options for resource control of spawned processes. Internally, this relies on the 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 for an introduction on how to make use of resource control APIs from programs.
Units with the Slice=
setting set get
automatic Requires=
and
After=
dependencies on the specified slice
unit.
Unified control group hierarchy is the new version of kernel control group interface. Depending on the resource type, there are differences in resource control capabilities. Also, because of interface changes, some resource types have a separate set of options on the 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.
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).
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.
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.
These options imply
"CPUAccounting=true
".
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.cfs_quota_us
" control group
attribute. For details about this control group attribute,
see sched-design-CFS.txt.
Example: CPUQuota=20%
ensures that
the executed processes will never get more than 20% CPU time
on one CPU.
Implies "CPUAccounting=true
".
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).
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. 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.
Implies "MemoryAccounting=true
".
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. 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.
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. 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.
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.
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.
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.
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.
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.
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.
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.
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, cpuacct.txt, memory.txt, blkio-controller.txt.