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From:   Shakeel Butt <shakeelb@google.com>
Date:   Wed, 30 Jan 2019 11:37:41 -0800
Message-ID: <CALvZod65htZmApWkv-MrAjg6V1OGBLmdyFP_030LARD7ajS3mw@mail.gmail.com>
Subject: Re: [PATCH 2/2] mm: Consider subtrees in memory.events
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Tejun Heo <tj@kernel.org>, Michal Hocko <mhocko@kernel.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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On Wed, Jan 30, 2019 at 11:30 AM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> On Wed, Jan 30, 2019 at 02:27:12PM -0500, Johannes Weiner wrote:
> > On Wed, Jan 30, 2019 at 11:11:44AM -0800, Shakeel Butt wrote:
> > > Hi Tejun,
> > >
> > > On Wed, Jan 30, 2019 at 9:07 AM Tejun Heo <tj@kernel.org> wrote:
> > > >
> > > > Hello, Michal.
> > > >
> > > > On Wed, Jan 30, 2019 at 05:50:58PM +0100, Michal Hocko wrote:
> > > > > > Yeah, cgroup.events and .stat files as some of the local stats would
> > > > > > be useful too, so if we don't flip memory.events we'll end up with sth
> > > > > > like cgroup.events.local, memory.events.tree and memory.stats.local,
> > > > > > which is gonna be hilarious.
> > > > >
> > > > > Why cannot we simply have memory.events_tree and be done with it? Sure
> > > > > the file names are not goin to be consistent which is a minus but that
> > > > > ship has already sailed some time ago.
> > > >
> > > > Because the overall cost of shitty interface will be way higher in the
> > > > longer term.  cgroup2 interface is far from perfect but is way better
> > > > than cgroup1 especially for the memory controller.  Why do you think
> > > > that is?
> > > >
> > >
> > > I thought you are fine with the separate interface for the hierarchical events.
> >
> > Every other file in cgroup2 is hierarchical, but for recursive
> > memory.events you'd need to read memory.events_tree?
> >
> > Do we hate our users that much? :(
>
> FTR, I would be okay with adding .local versions to existing files
> where such a behavior could be useful. But that seems to be a separate
> discussion from fixing memory.events here.

Oh ok, the dispute is on the name of the interface. I am fine with
whatever the decision is made as we (Google) are still not using these
interfaces. However what's the way forward here?

thanks,
Shakeel