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From: "T.J. Mercier" <tjmercier@google.com>
Date: Tue, 28 May 2024 16:02:38 -0700
Message-ID: <CABdmKX2LrdAC2YtkShr+rNM_Ng8586AowH9Uu2ZGhzmX+YH6DQ@mail.gmail.com>
Subject: Re: [PATCH 1/2] cgroup: Fix /proc/cgroups count for v2
To: Tejun Heo <tj@kernel.org>
Cc: =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>, 
	Zefan Li <lizefan.x@bytedance.com>, Johannes Weiner <hannes@cmpxchg.org>, shakeel.butt@linux.dev, 
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, May 28, 2024 at 3:45=E2=80=AFPM T.J. Mercier <tjmercier@google.com>=
 wrote:
>
> On Tue, May 28, 2024 at 3:42=E2=80=AFPM Tejun Heo <tj@kernel.org> wrote:
> >
> > On Tue, May 28, 2024 at 03:38:01PM -0700, T.J. Mercier wrote:
> > > > > I think it would make sense to introduce something in a similar
> > > > > fashion. Can't think of a good name off the top of my head but ad=
d a
> > > > > cgroup. file which lists the controllers in the subtree along wit=
h the
> > > > > number of css's.
> > > >
> > > > BTW, there is the 'debug' subsys that has (almost) exactly that:
> > > > 'debug.csses' -- it's in v1 fashion though so it won't show hierarc=
hical
> > > > sums.
> >
> > Yeah, something like that but hierarchical and built into cgroup2 inter=
face.
> > Would that work for your use case?
> >
> I think so, I'm checking this out now. debug as v1-only and non-stable
> interface files doesn't work, but the same sort of thing with a stable
> interface on v2 seems like it would.
>
Ok debug.cgroup_subsys_states reports css->css->online_cnt, but I'd
also want to include the number that are dying. Either as a separate
count or combined with the online_cnt like in /proc/cgroups.