The patch titled
Subject: mm/docs: describe memory.low refinements
has been added to the -mm tree. Its filename is
mm-docs-describe-memorylow-refinements.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-docs-describe-memorylow-refinements.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-docs-describe-memorylow-refinements.patch
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------------------------------------------------------
From: Roman Gushchin <guro@xxxxxx>
Subject: mm/docs: describe memory.low refinements
Refine cgroup v2 docs after latest memory.low changes.
Link: http://lkml.kernel.org/r/20180405185921.4942-4-guro@xxxxxx
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/cgroup-v2.txt | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
diff -puN Documentation/cgroup-v2.txt~mm-docs-describe-memorylow-refinements Documentation/cgroup-v2.txt
--- a/Documentation/cgroup-v2.txt~mm-docs-describe-memorylow-refinements
+++ a/Documentation/cgroup-v2.txt
@@ -1005,10 +1005,17 @@ PAGE_SIZE multiple when read back.
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 the its
+ actual memory usage below memory.low.
Putting more memory than generally available under this
protection is discouraged.
@@ -1950,17 +1957,8 @@ system performance due to overreclaim, t
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.
_
Patches currently in -mm which might be from guro@xxxxxx are
mm-rename-page_counters-count-limit-into-usage-max.patch
mm-memorylow-hierarchical-behavior.patch
mm-treat-memorylow-value-inclusive.patch
mm-docs-describe-memorylow-refinements.patch
mm-oom-refactor-the-oom_kill_process-function.patch
mm-implement-mem_cgroup_scan_tasks-for-the-root-memory-cgroup.patch
mm-oom-cgroup-aware-oom-killer.patch
mm-oom-introduce-memoryoom_group.patch
mm-oom-introduce-memoryoom_group-fix.patch
mm-oom-add-cgroup-v2-mount-option-for-cgroup-aware-oom-killer.patch
mm-oom-docs-describe-the-cgroup-aware-oom-killer.patch
mm-oom-docs-describe-the-cgroup-aware-oom-killer-fix.patch
cgroup-list-groupoom-in-cgroup-features.patch
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