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NAME | SYNOPSIS | DESCRIPTION | AUTOMATIC DEPENDENCIES | OPTIONS | SEE ALSO | NOTES | COLOPHON |
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SYSTEMD.SLICE(5) systemd.slice SYSTEMD.SLICE(5)
systemd.slice - Slice unit configuration
slice.slice
A unit configuration file whose name ends in ".slice" encodes
information about a slice unit. A slice unit is a concept for
hierarchically managing resources of a group of processes. This
management is performed by creating a node in the Linux Control
Group (cgroup) tree. Units that manage processes (primarily scope
and service units) may be assigned to a specific slice. For each
slice, certain resource limits may be set that apply to all
processes of all units contained in that slice. Slices are
organized hierarchically in a tree. The name of the slice encodes
the location in the tree. The name consists of a dash-separated
series of names, which describes the path to the slice from the
root slice. The root slice is named -.slice. Example:
foo-bar.slice is a slice that is located within foo.slice, which
in turn is located in the root slice -.slice.
Note that slice units cannot be templated, nor is possible to add
multiple names to a slice unit by creating additional symlinks to
its unit file.
By default, service and scope units are placed in system.slice,
virtual machines and containers registered with
systemd-machined(8) are found in machine.slice, and user sessions
handled by systemd-logind(8) in user.slice. See systemd.special(7)
for more information.
See systemd.unit(5) for the common options of all unit
configuration files. The common configuration items are configured
in the generic [Unit] and [Install] sections. The slice specific
configuration options are configured in the [Slice] section.
Currently, only generic resource control settings as described in
systemd.resource-control(5) are allowed.
See the New Control Group Interfaces[1] for an introduction on how
to make use of slice units from programs.
Implicit Dependencies
The following dependencies are implicitly added:
• Slice units automatically gain dependencies of type After= and
Requires= on their immediate parent slice unit.
Default Dependencies
The following dependencies are added unless DefaultDependencies=no
is set:
• Slice units will automatically have dependencies of type
Conflicts= and Before= on shutdown.target. These ensure that
slice units are removed prior to system shutdown. Only slice
units involved with late system shutdown should disable
DefaultDependencies= option.
Slice unit files may include [Unit] and [Install] sections, which
are described in systemd.unit(5).
Slice files may include a [Slice] section. Many options that may
be used in this section are shared with other unit types. These
options are documented in systemd.resource-control(5).
The options specific to the [Slice] section of slice units are the
following:
ConcurrencyHardMax=, ConcurrencySoftMax=
Configures a hard and a soft limit on the maximum number of
units assigned to this slice (or any descendent slices) that
may be active at the same time. If the hard limit is reached
no further units associated with the slice may be activated,
and their activation will fail with an error. If the soft
limit is reached any further requested activation of units
will be queued, but no immediate error is generated. The
queued activation job will remain queued until the number of
concurrent active units within the slice is below the limit
again.
If the special value "infinity" is specified, no concurrency
limit is enforced. This is the default.
Note that if multiple start jobs are queued for units, and all
their dependencies are fulfilled they'll be processed in an
order that is dependent on the unit type, the CPU weight (for
unit types that know the concept, such as services), the nice
level (similar), and finally in alphabetical order by the unit
name. This may be used to influence dispatching order when
using ConcurrencySoftMax= to pace concurrency within a slice
unit.
Note that these options have a hierarchial effect: a limit set
for a slice unit will apply to both the units immediately
within the slice, but also all units further down the slice
tree. Also note that each sub-slice unit counts as one unit
each too, and thus when choosing a limit for a slice hierarchy
the limit must provide room for both the payload units (i.e.
services, mounts, ...) and structural units (i.e. slice
units), if any are defined.
Added in version 258.
systemd(1), systemd.unit(5), systemd.resource-control(5),
systemd.service(5), systemd.scope(5), systemd.special(7),
systemd.directives(7)
1. New Control Group Interfaces
https://systemd.io/CONTROL_GROUP_INTERFACE
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 258~rc2 SYSTEMD.SLICE(5)
Pages that refer to this page: journalctl(1), systemd(1), systemd-nspawn(1), systemd-run(1), sd_bus_creds_get_pid(3), sd_pid_get_owner_uid(3), [email protected](5), systemd.resource-control(5), systemd.service(5), systemd.unit(5), [email protected](5), systemd.directives(7), systemd.index(7), systemd.special(7), systemd.syntax(7), pam_systemd(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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