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Diffstat (limited to 'Documentation/admin-guide/cgroup-v2.rst')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 0fa8c0e615c2..5361ebec3361 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -615,8 +615,8 @@ on an IO device and is an example of this type. Protections ----------- -A cgroup is protected to be allocated upto the configured amount of -the resource if the usages of all its ancestors are under their +A cgroup is protected upto the configured amount of the resource +as long as the usages of all its ancestors are under their protected levels. Protections can be hard guarantees or best effort soft boundaries. Protections can also be over-committed in which case only upto the amount available to the parent is protected among @@ -1096,7 +1096,10 @@ PAGE_SIZE multiple when read back. is within its effective min boundary, the cgroup's memory won't be reclaimed under any conditions. If there is no unprotected reclaimable memory available, OOM killer - is invoked. + is invoked. Above the effective min boundary (or + effective low boundary if it is higher), pages are reclaimed + proportionally to the overage, reducing reclaim pressure for + smaller overages. Effective min boundary is limited by memory.min values of all ancestor cgroups. If there is memory.min overcommitment @@ -1118,7 +1121,10 @@ PAGE_SIZE multiple when read back. Best-effort memory protection. If the memory usage of a cgroup is within its effective low boundary, the cgroup's memory won't be reclaimed unless memory can be reclaimed - from unprotected cgroups. + from unprotected cgroups. Above the effective low boundary (or + effective min boundary if it is higher), pages are reclaimed + proportionally to the overage, reducing reclaim pressure for + smaller overages. Effective low boundary is limited by memory.low values of all ancestor cgroups. If there is memory.low overcommitment @@ -2482,8 +2488,10 @@ system performance due to overreclaim, to the point where the feature becomes self-defeating. The memory.low boundary on the other hand is a top-down allocated -reserve. A cgroup enjoys reclaim protection when it's within its low, -which makes delegation of subtrees possible. +reserve. A cgroup enjoys reclaim protection when it's within its +effective low, which makes delegation of subtrees possible. It also +enjoys having reclaim pressure proportional to its overage when +above its effective low. The original high boundary, the hard limit, is defined as a strict limit that can not budge, even if the OOM killer has to be called. |