@@ -615,8 +615,8 @@ on an IO device and is an example of this type.
615615Protections
616616-----------
617617
618- A cgroup is protected to be allocated upto the configured amount of
619- the resource if the usages of all its ancestors are under their
618+ A cgroup is protected upto the configured amount of the resource
619+ as long as the usages of all its ancestors are under their
620620protected levels. Protections can be hard guarantees or best effort
621621soft boundaries. Protections can also be over-committed in which case
622622only upto the amount available to the parent is protected among
@@ -1096,7 +1096,10 @@ PAGE_SIZE multiple when read back.
10961096 is within its effective min boundary, the cgroup's memory
10971097 won't be reclaimed under any conditions. If there is no
10981098 unprotected reclaimable memory available, OOM killer
1099- is invoked.
1099+ is invoked. Above the effective min boundary (or
1100+ effective low boundary if it is higher), pages are reclaimed
1101+ proportionally to the overage, reducing reclaim pressure for
1102+ smaller overages.
11001103
11011104 Effective min boundary is limited by memory.min values of
11021105 all ancestor cgroups. If there is memory.min overcommitment
@@ -1118,7 +1121,10 @@ PAGE_SIZE multiple when read back.
11181121 Best-effort memory protection. If the memory usage of a
11191122 cgroup is within its effective low boundary, the cgroup's
11201123 memory won't be reclaimed unless memory can be reclaimed
1121- from unprotected cgroups.
1124+ from unprotected cgroups. Above the effective low boundary (or
1125+ effective min boundary if it is higher), pages are reclaimed
1126+ proportionally to the overage, reducing reclaim pressure for
1127+ smaller overages.
11221128
11231129 Effective low boundary is limited by memory.low values of
11241130 all ancestor cgroups. If there is memory.low overcommitment
@@ -2482,8 +2488,10 @@ system performance due to overreclaim, to the point where the feature
24822488becomes self-defeating.
24832489
24842490The memory.low boundary on the other hand is a top-down allocated
2485- reserve. A cgroup enjoys reclaim protection when it's within its low,
2486- which makes delegation of subtrees possible.
2491+ reserve. A cgroup enjoys reclaim protection when it's within its
2492+ effective low, which makes delegation of subtrees possible. It also
2493+ enjoys having reclaim pressure proportional to its overage when
2494+ above its effective low.
24872495
24882496The original high boundary, the hard limit, is defined as a strict
24892497limit that can not budge, even if the OOM killer has to be called.
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