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SYSTEMD.RESOURCE-CONTROL(5) systemd.resource-control SYSTEMD.RESOURCE-CONTROL(5)
NAME
systemd.resource-control - Resource control unit settings
SYNOPSIS
slice.slice, scope.scope, service.service, socket.socket, mount.mount, swap.swap
DESCRIPTION
Unit configuration files for services, slices, scopes, sockets, mount points, and swap
devices share a subset of configuration options for resource control of spawned processes.
Internally, this relies on the 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.
OPTIONS
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).
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[2]. 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[2].
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[3].
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.
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[4].
Implies "TasksAccounting=true". The system default for this setting may be controlled
with DefaultTasksMax= in systemd-system.conf(5).
BlockIOAccounting=
Turn on Block IO accounting for this unit. Takes a boolean argument. Note that turning
on block IO 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).
BlockIOWeight=weight, StartupBlockIOWeight=weight
Set the default overall block IO weight for the executed processes. Takes a single
weight value (between 10 and 1000) to set the default block IO weight. This controls
the "blkio.weight" control group attribute, which defaults to 500. For details about
this control group attribute, see blkio-controller.txt[5]. The available IO bandwidth
is split up among all units within one slice relative to their block IO 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".
BlockIODeviceWeight=device weight
Set the per-device overall block IO weight for the executed processes. 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[5].
Implies "BlockIOAccounting=true".
BlockIOReadBandwidth=device bytes, BlockIOWriteBandwidth=device bytes
Set the per-device overall block IO bandwidth limit for the executed processes. 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.read_bps_device" and "blkio.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[5].
Implies "BlockIOAccounting=true".
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[6].
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.
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
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[7], cpuacct.txt[8], memory.txt[3], blkio-controller.txt[5].
NOTES
1. New Control Group Interfaces
http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/
2. sched-design-CFS.txt
https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt
3. memory.txt
https://www.kernel.org/doc/Documentation/cgroups/memory.txt
4. pids.txt
https://www.kernel.org/doc/Documentation/cgroup-v1/pids.txt
5. blkio-controller.txt
https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt
6. devices.txt
https://www.kernel.org/doc/Documentation/cgroups/devices.txt
7. cgroups.txt
https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt
8. cpuacct.txt
https://www.kernel.org/doc/Documentation/cgroups/cpuacct.txt
systemd 219 SYSTEMD.RESOURCE-CONTROL(5)
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