Re: [RFC PATCH] memcg: use root_mem_cgroup when css is inherited

On Fri, Aug 19, 2022 at 07:29:22PM +0800, zhaoyang.huang wrote:

From: Zhaoyang Huang <redacted>

It is observed in android system where per-app cgroup is demanded by freezer
subsys and part of groups require memory control. The hierarchy could be simplized
as bellowing where memory charged on group B abserved while we only want have
group E's memory be controlled and B's descendants compete freely for memory.
This should be the consequences of unified hierarchy.
Under this scenario, less efficient memory reclaim is observed when comparing
with no memory control. It is believed that multi LRU scanning introduces some
of the overhead. Furthermore, page thrashing is also heavier than global LRU
which could be the consequences of partial failure of WORKINGSET mechanism as
LRU is too short to protect the active pages.

A(subtree_control = memory) - B(subtree_control = NULL) - C()
							\ D()
			    - E(subtree_control = memory) - F()
							  \ G()

Signed-off-by: Zhaoyang Huang <redacted>

Just in case it wasn't clear.

Nacked-by: Tejun Heo [off-list ref]

Thanks.

-- 
tejun