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From:   Shakeel Butt <shakeelb@google.com>
Date:   Mon, 28 Jan 2019 08:08:26 -0800
Message-ID: <CALvZod5Rrr6ENW5yLNzniFeFmGB=mDRH+guNLmcayTX-_xDAGw@mail.gmail.com>
Subject: Re: [PATCH 2/2] mm: Consider subtrees in memory.events
To:     Tejun Heo <tj@kernel.org>
Cc:     Michal Hocko <mhocko@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Chris Down <chris@chrisdown.name>,
        Andrew Morton <akpm@linux-foundation.org>,
        Roman Gushchin <guro@fb.com>, Dennis Zhou <dennis@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        kernel-team@fb.com
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Hi Tejun,

On Mon, Jan 28, 2019 at 8:05 AM Tejun Heo <tj@kernel.org> wrote:
>
> Hello, Shakeel.
>
> On Mon, Jan 28, 2019 at 07:59:33AM -0800, Shakeel Butt wrote:
> > Why not make this configurable at the delegation boundary? As you
> > mentioned, there are jobs who want centralized workload manager to
> > watch over their subtrees while there can be jobs which want to
> > monitor their subtree themselves. For example I can have a job which
> > know how to act when one of the children cgroup goes OOM. However if
> > the root of that job goes OOM then the centralized workload manager
> > should do something about it. With this change, how to implement this
> > scenario? How will the central manager differentiates between that a
> > subtree of a job goes OOM or the root of that job? I guess from the
> > discussion it seems like the centralized manager has to traverse that
> > job's subtree to find the source of OOM.
> >
> > Why can't we let the implementation of centralized manager easier by
> > allowing to configure the propagation of these notifications across
> > delegation boundary.
>
> I think the right way to achieve the above would be having separate
> recursive and local counters.
>

Do you envision a separate interface/file for recursive and local
counters? That would make notifications simpler but that is an
additional interface.

Shakeel