Understanding the history of cgroups

This might shock you, but the cgroups technology didn't start as a part of systemd, and it wasn't invented by Red Hat. It's actually a component in the Linux kernel that can run on non-systemd Linux distros. A pair of Google engineers started cgroups development back in 2006, four years before Red Hat engineers started developing systemd. The first enterprise-grade Linux distro to include cgroups technology was Red Hat Enterprise Linux 6, which ran a hybrid upstart/SysV setup instead of systemd. Using cgroups on RHEL 6 was optional, and you had to jump through some hoops to set them up.

Nowadays, cgroups are enabled by default on all of the major enterprise-type Linux distros and are tightly integrated with systemd. RHEL 7 was the first enterprise distro to use systemd and was also the first enterprise distro to always have cgroups enabled.

There are currently two versions of the cgroups technology. Version 1 works well for...