slice unit
also: cgroup slice, systemd slice
A systemd unit type that groups processes into a hierarchy for resource management and control. Slices organize cgroups (control groups) to limit CPU, memory, and other resources allocated to sets of services.
A slice unit is a systemd concept that creates a hierarchical container for organizing and managing system resources. Slices map directly to Linux control groups (cgroups), which enforce limits on CPU usage, memory, I/O, and other resources.
The slice hierarchy is tree-structured: -.slice is the root, with system.slice and user.slice as common parent slices. Services and scopes inherit resource limits from their parent slices. For example, all user login sessions might run under user.slice, allowing administrators to cap total memory used by all users.
You can inspect slices with systemctl -t slice or systemd-cgls. Custom slices are rarely needed in typical setups, but they're powerful for multi-tenant systems or containerized environments where strict resource isolation is critical.