systemd Developer Lennart Poettering lennart@poettering.net systemd.cgroup 5 systemd.cgroup Control Group configuration unit settings slice.slice, scope.scope, service.service, socket.socket, mount.mount, swap.swap Unit configuration files for services, slices, scopes, sockets, mount points, and swap devices share a subset of configuration options which configure the control group settings for spawned processes. Control Groups is a concept for organizing processes in a hierarch 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.unit5 for the common options of all unit configuration files, and systemd.slice5, systemd.scope5, systemd.service5, systemd.socket5, systemd.mount5, and systemd.swap5 for more information on the specific unit configuration files. The execution-specific configuration options are configured in the [Slice], [Scope], [Service], [Socket], [Mount], or [Swap] sections, depending on the unit type. Units of the types listed above can have settings for cgroup configuration: CPUAccounting= Turn on CPU usage accounting for this unit. Takes a boolean argument. Note that turning on CPU accounting for one unit might also implicitly turn it on for all units contained in the same slice and for all its parent slices and the units contained therein. CPUShares=weight Assign the specified overall CPU time share weight to the processes executed. Takes an integer value. This controls the cpu.shares control group attribute, which defaults to 1024. For details about this control group attribute, see sched-design-CFS.txt. 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 might also implicitly turn it on for all units contained in the same slice and for all its parent slices and the units contained therein. MemoryLimit=bytes MemorySoftLimit=bytes Specify the hard and soft limits on maximum memory usage of the executed processes. The "hard" limit specifies how much process and kernel memory can be used by tasks in this unit, when there is no memory contention. If the kernel detects memory contention, memory reclaim will be performed until the memory usage is within the "soft" limit. 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. This controls the memory.limit_in_bytes and memory.soft_limit_in_bytes control group attributes. For details about these control group attributes, see memory.txt. Implies MemoryAccounting=true. BlockIOAccounting= Turn on Block IO accounting for this unit. Takes a boolean argument. Note that turning on block IO accounting for one unit might also implicitly turn it on for all units contained in the same slice and all for its parent slices and the units contained therein. BlockIOWeight=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 1000. For details about this control group attribute, see blkio-controller.txt. 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. 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 (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. Implies BlockIOAccounting=true. DeviceAllow= Control access to specific device nodes by the executed processes. Takes two space-separated strings: a device node path (such as /dev/null) followed by a combination of r, w, m to control reading, writing, or creation of the specific device node 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. 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. systemd1, systemd.unit5, systemd.service5, systemd.slice5, systemd.scope5, systemd.socket5, systemd.mount5, systemd.swap5, systemd.directives7, systemd.special7, The documentation for control groups and specific controllers in the Linux kernel: cgroups.txt, cpuacct.txt, memory.txt, blkio-controller.txt.