[RFC][PATCH 0/2] memcg: simple hierarchy (v2)
This is rewritten version of memcg hierarchy handling.
...and I'm sorry tons of typos in v1.
Changelog:
- fixed typo.
- removed meaningless params (borrow)
- renamed structure members.
not-for-test. just for discussion. (I'll rewrite when our direction is fixed.)
Implemented Policy:
- parent overcommits all children
parent->usage = resource used by itself + resource moved to children.
Of course, parent->limit > parent->usage.
- when child's limit is set, the resouce moves.
- no automatic resource moving between parent <-> child
Example)
1) Assume a cgroup with 1GB limits. (and no tasks belongs to this, now)
- group_A limit=1G,usage=0M.
2) create group B, C under A.
- group A limit=1G, usage=0M
- group B limit=0M, usage=0M.
- group C limit=0M, usage=0M.
3) increase group B's limit to 300M.
- group A limit=1G, usage=300M.
- group B limit=300M, usage=0M.
- group C limit=0M, usage=0M.
4) increase group C's limit to 500M
- group A limit=1G, usage=800M.
- group B limit=300M, usage=0M.
- group C limit=500M, usage=0M.
5) reduce group B's limit to 100M
- group A limit=1G, usage=600M.
- group B limit=100M, usage=0M.
- group C limit=500M, usage=0M.
Why this is enough ?
- A middleware can do various kind of resource balancing only by reseting "limit"
in userland.
TODO(maybe)
- rewrite force_empty to move the resource to the parent.
Thanks,
-Kame
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