Cgroups

cgroups (abbreviated from control groups) is a Linux kernel feature that limits, accounts for, and isolates the resource usage (CPU, memory, disk I/O, etc.) of a collection of processes. Engineers at Google started the work on this feature in 2006 under the name "process containers". In late 2007, the nomenclature changed to "control groups" to avoid confusion caused by multiple meanings of the term "container" in the Linux kernel context, and the control groups functionality was merged into the Linux kernel mainline in kernel version 2.6.24, which was released in January 2008. Since then, developers have added controllers for the kernel's own memory allocation, netfilter firewalling, the OOM killer, and many other parts. A major change in the history of cgroups is cgroup v2, which removes the ability to use multiple process hierarchies and to discriminate between threads as found in the original cgroup (now called "v1"). Work on the single, unified hierarchy started with the repurposing of v1's dummy hierarchy as a place for holding all controllers not yet used by others in 2014. cgroup v2 was merged in Linux kernel 4.5 (2016).