Control Group v2
October, 2015 Tejun Heo <tj@kernel.org>
This is the authoritative documentation on the design, interface and
conventions of cgroup v2. It describes all userland-visible aspects
of cgroup including core and specific controller behaviors. All
future changes must be reflected in this document. Documentation for
v1 is available under Documentation/cgroup-v1/.
CONTENTS
1. Introduction
1-1. Terminology
1-2. What is cgroup?
2. Basic Operations
2-1. Mounting
2-2. Organizing Processes
2-3. [Un]populated Notification
2-4. Controlling Controllers
2-4-1. Enabling and Disabling
2-4-2. Top-down Constraint
2-4-3. No Internal Process Constraint
2-5. Delegation
2-5-1. Model of Delegation
2-5-2. Delegation Containment
2-6. Guidelines
2-6-1. Organize Once and Control
2-6-2. Avoid Name Collisions
3. Resource Distribution Models
3-1. Weights
3-2. Limits
3-3. Protections
3-4. Allocations
4. Interface Files
4-1. Format
4-2. Conventions
4-3. Core Interface Files
5. Controllers
5-1. CPU
5-1-1. CPU Interface Files
5-2. Memory
5-2-1. Memory Interface Files
5-2-2. Usage Guidelines
5-2-3. Memory Ownership
5-3. IO
5-3-1. IO Interface Files
5-3-2. Writeback
6. Namespace
6-1. Basics
6-2. The Root and Views
6-3. Migration and setns(2)
6-4. Interaction with Other Namespaces
P. Information on Kernel Programming
P-1. Filesystem Support for Writeback
D. Deprecated v1 Core Features
R. Issues with v1 and Rationales for v2
R-1. Multiple Hierarchies
R-2. Thread Granularity
R-3. Competition Between Inner Nodes and Threads
R-4. Other Interface Issues
R-5. Controller Issues and Remedies
R-5-1. Memory
1. Introduction
1-1. Terminology
"cgroup" stands for "control group" and is never capitalized. The
singular form is used to designate the whole feature and also as a
qualifier as in "cgroup controllers". When explicitly referring to
multiple individual control groups, the plural form "cgroups" is used.
1-2. What is cgroup?
cgroup is a mechanism to organize processes hierarchically and
distribute system resources along the hierarchy in a controlled and
co