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Diffstat (limited to 'Documentation/admin-guide/cgroup-v2.rst')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 72 |
1 files changed, 57 insertions, 15 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 74cdeaed9f7a..8a2c52d5c53b 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1001,14 +1001,44 @@ PAGE_SIZE multiple when read back. The total amount of memory currently being used by the cgroup and its descendants. + memory.min + A read-write single value file which exists on non-root + cgroups. The default is "0". + + Hard memory protection. If the memory usage of a cgroup + 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. + + Effective min boundary is limited by memory.min values of + all ancestor cgroups. If there is memory.min overcommitment + (child cgroup or cgroups are requiring more protected memory + than parent will allow), then each child cgroup will get + the part of parent's protection proportional to its + actual memory usage below memory.min. + + Putting more memory than generally available under this + protection is discouraged and may lead to constant OOMs. + + If a memory cgroup is not populated with processes, + its memory.min is ignored. + memory.low A read-write single value file which exists on non-root cgroups. The default is "0". - Best-effort memory protection. If the memory usages of a - cgroup and all its ancestors are below their low boundaries, - the cgroup's memory won't be reclaimed unless memory can be - reclaimed from unprotected cgroups. + 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. + + Effective low boundary is limited by memory.low values of + all ancestor cgroups. If there is memory.low overcommitment + (child cgroup or cgroups are requiring more protected memory + than parent will allow), then each child cgroup will get + the part of parent's protection proportional to its + actual memory usage below memory.low. Putting more memory than generally available under this protection is discouraged. @@ -1199,6 +1229,27 @@ PAGE_SIZE multiple when read back. Swap usage hard limit. If a cgroup's swap usage reaches this limit, anonymous memory of the cgroup will not be swapped out. + memory.swap.events + A read-only flat-keyed file which exists on non-root cgroups. + The following entries are defined. Unless specified + otherwise, a value change in this file generates a file + modified event. + + max + The number of times the cgroup's swap usage was about + to go over the max boundary and swap allocation + failed. + + fail + The number of times swap allocation failed either + because of running out of swap system-wide or max + limit. + + When reduced under the current usage, the existing swap + entries are reclaimed gradually and the swap usage may stay + higher than the limit for an extended period of time. This + reduces the impact on the workload and memory management. + Usage Guidelines ~~~~~~~~~~~~~~~~ @@ -1934,17 +1985,8 @@ 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 and all its -ancestors are below their low boundaries, which makes delegation of -subtrees possible. Secondly, new cgroups have no reserve per default -and in the common case most cgroups are eligible for the preferred -reclaim pass. This allows the new low boundary to be efficiently -implemented with just a minor addition to the generic reclaim code, -without the need for out-of-band data structures and reclaim passes. -Because the generic reclaim code considers all cgroups except for the -ones running low in the preferred first reclaim pass, overreclaim of -individual groups is eliminated as well, resulting in much better -overall workload performance. +reserve. A cgroup enjoys reclaim protection when it's within its low, +which makes delegation of subtrees possible. 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. |