Operations

Cgroup

Linux mechanism that limits and accounts CPU, memory, IO for a process tree.

In plain terms

Plus namespaces = container. cgroupv2 unified the interface in 2016; required for systemd and modern container runtimes.

Origin

Paul Menage at Google merged cgroups into Linux 2.6.24 (2007). cgroup v2 unified the interface in Linux 4.5 (2016); required for modern container runtimes and systemd.

Where it shows up in production

Docker / containerd Container = cgroup + namespaces + layered filesystem. cgroup limits CPU, memory, IO.
Kubernetes resource limits CPU/memory requests + limits translate to cgroup parameters on the node.

Sources & further reading

Docs Linux — Control Groups v2 docs

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