SYSTEMD.RESOURCE-CONTROL(5)systemd.resource-controlSYSTEMD.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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