Cgroups
| Original author(s) | Paul Menage, Rohit Seth |
|---|---|
| Developer(s) | kernel.org (Tejun Heo et al.) and freedesktop.org |
| Initial release | 2007 |
| Written in | C |
| Operating system | Linux |
| Type | System software |
| License | GPL and LGPL |
| Website |
www |
cgroups (abbreviated from control groups) is a Linux kernel feature that limits, accounts for, and isolates the resource usage (CPU, memory, disk I/O, network, etc.) of a collection of processes.
Engineers at Google (primarily Paul Menage and Rohit Seth) 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 many new features and controllers, such as support for kernfs,firewalling, and unified hierarchy.
There are two versions of cgroups.
Cgroups was originally written by Paul Menage et al. and mainlined into the Linux kernel in 2007. Afterwards this is called cgroups version 1.
Then development and maintenance of cgroups was taken over by Tejun Heo. Tejun Heo redesigned and rewrote cgroups. This rewrite is now called version 2, the documentation of cgroups-v2 first appeared in Linux kernel 4.5 released on March 14, 2016.
Unlike v1, cgroup v2 has only a single process hierarchy and discriminates between processes, not threads.
One of the design goals of cgroups is to provide a unified interface to many different use cases, from controlling single processes (by using nice, for example) to whole operating system-level virtualization (as provided by OpenVZ, Linux-VServer or LXC, for example). Cgroups provides:
A control group (abbreviated as cgroup) is a collection of processes that are bound by the same criteria and associated with a set of parameters or limits. These groups can be hierarchical, meaning that each group inherits limits from its parent group. The kernel provides access to multiple controllers (also called subsystems) through the cgroup interface; for example, the "memory" controller limits memory use, "cpuacct" accounts CPU usage, etc.
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