linux-kernel - Re: [RFC PATCH] memcg: use root_mem

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Date:   Fri, 19 Aug 2022 10:08:59 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Tejun Heo <tj@...nel.org>
Cc:     "zhaoyang.huang" <zhaoyang.huang@...soc.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Zhaoyang Huang <huangzhaoyang@...il.com>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Cgroups <cgroups@...r.kernel.org>, ke.wang@...soc.com,
        Zefan Li <lizefan.x@...edance.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Muchun Song <songmuchun@...edance.com>
Subject: Re: [RFC PATCH] memcg: use root_mem_cgroup when css is inherited

On Fri, Aug 19, 2022 at 9:29 AM Tejun Heo <tj@...nel.org> wrote:
>
> On Fri, Aug 19, 2022 at 07:29:22PM +0800, zhaoyang.huang wrote:
> > From: Zhaoyang Huang <zhaoyang.huang@...soc.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@...soc.com>
>
> Just in case it wasn't clear.
>
> Nacked-by: Tejun Heo <tj@...nel.org>
>
> Thanks.
>

Was there a previous discussion on this? The commit message is unreadable.