diff options
Diffstat (limited to 'Documentation/cgroups')
| -rw-r--r-- | Documentation/cgroups/unified-hierarchy.txt | 80 |
1 files changed, 72 insertions, 8 deletions
diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt index 86847a7647ab..1ee9caf29e57 100644 --- a/Documentation/cgroups/unified-hierarchy.txt +++ b/Documentation/cgroups/unified-hierarchy.txt @@ -23,10 +23,13 @@ CONTENTS 5. Other Changes 5-1. [Un]populated Notification 5-2. Other Core Changes - 5-3. Per-Controller Changes - 5-3-1. blkio - 5-3-2. cpuset - 5-3-3. memory + 5-3. Controller File Conventions + 5-3-1. Format + 5-3-2. Control Knobs + 5-4. Per-Controller Changes + 5-4-1. blkio + 5-4-2. cpuset + 5-4-3. memory 6. Planned Changes 6-1. CAP for resource control @@ -372,14 +375,75 @@ supported and the interface files "release_agent" and - The "cgroup.clone_children" file is removed. -5-3. Per-Controller Changes +5-3. Controller File Conventions -5-3-1. blkio +5-3-1. Format + +In general, all controller files should be in one of the following +formats whenever possible. + +- Values only files + + VAL0 VAL1...\n + +- Flat keyed files + + KEY0 VAL0\n + KEY1 VAL1\n + ... + +- Nested keyed files + + KEY0 SUB_KEY0=VAL00 SUB_KEY1=VAL01... + KEY1 SUB_KEY0=VAL10 SUB_KEY1=VAL11... + ... + +For a writeable file, the format for writing should generally match +reading; however, controllers may allow omitting later fields or +implement restricted shortcuts for most common use cases. + +For both flat and nested keyed files, only the values for a single key +can be written at a time. For nested keyed files, the sub key pairs +may be specified in any order and not all pairs have to be specified. + + +5-3-2. Control Knobs + +- Settings for a single feature should generally be implemented in a + single file. + +- In general, the root cgroup should be exempt from resource control + and thus shouldn't have resource control knobs. + +- If a controller implements ratio based resource distribution, the + control knob should be named "weight" and have the range [1, 10000] + and 100 should be the default value. The values are chosen to allow + enough and symmetric bias in both directions while keeping it + intuitive (the default is 100%). + +- If a controller implements an absolute resource guarantee and/or + limit, the control knobs should be named "min" and "max" + respectively. If a controller implements best effort resource + gurantee and/or limit, the control knobs should be named "low" and + "high" respectively. + + In the above four control files, the special token "max" should be + used to represent upward infinity for both reading and writing. + +- If a setting has configurable default value and specific overrides, + the default settings should be keyed with "default" and appear as + the first entry in the file. Specific entries can use "default" as + its value to indicate inheritance of the default value. + + +5-4. Per-Controller Changes + +5-4-1. blkio - blk-throttle becomes properly hierarchical. -5-3-2. cpuset +5-4-2. cpuset - Tasks are kept in empty cpusets after hotplug and take on the masks of the nearest non-empty ancestor, instead of being moved to it. @@ -388,7 +452,7 @@ supported and the interface files "release_agent" and masks of the nearest non-empty ancestor. -5-3-3. memory +5-4-3. memory - use_hierarchy is on by default and the cgroup file for the flag is not created. |