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

[Tejun Heo <tj@kernel.org>]

On Fri, Aug 19, 2022 at 07:29:22PM +0800, zhaoyang.huang wrote:
> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> 
> 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 <zhaoyang.huang@unisoc.com>

Just in case it wasn't clear.

Nacked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun