systemd.slice — Slice unit configuration
slice.slice
A unit configuration file whose name ends in
    ".slice" encodes information about a slice which
    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.
    
By default, service and scope units are placed in
    system.slice, virtual machines and containers
    registered with
    systemd-machined(1)
    are found in machine.slice, and user sessions
    handled by
    systemd-logind(1)
    in user.slice. See
    systemd.special(5)
    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(7) are allowed.
Unless DefaultDependencies=false
    is used, slice units will implicitly 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 early boot or
    late system shutdown should disable this option.