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From:   Max Kellermann <max.kellermann@ionos.com>
Date:   Tue, 26 Sep 2023 08:16:34 +0200
Message-ID: <CAKPOu+-yUOuVh+3818iJ-GH968EHHQ0Pc3d8Rj4veO3k-xLk+g@mail.gmail.com>
Subject: Re: [PATCH 1/2] fs/ceph/debugfs: make all files world-readable
To:     Ilya Dryomov <idryomov@gmail.com>
Cc:     Xiubo Li <xiubli@redhat.com>, Jeff Layton <jlayton@kernel.org>,
        ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org
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On Mon, Sep 25, 2023 at 12:42=E2=80=AFPM Ilya Dryomov <idryomov@gmail.com> =
wrote:
> A word of caution about building metrics collectors based on debugfs
> output: there are no stability guarantees.  While the format won't be
> changed just for the sake of change of course, expect zero effort to
> preserve backwards compatibility.

Agree, but there's nothing else. We have been using my patch for quite
some time, and it has been very useful.

Maybe we can discuss promoting these statistics to sysfs/proc? (the
raw numbers, not the existing aggregates which are useless for any
practical purpose)

> The latency metrics in particular are sent to the MDS in binary form
> and are intended to be consumed through commands like "ceph fs top".
> debugfs stuff is there just for an occasional sneak peek (apart from
> actual debugging).

I don't know the whole Ceph ecosystem so well, but "ceph" is a command
that is supposed to run on a Ceph server, and not on a machine that
mounts a cephfs, right? If that's right, then this command is useless
for me.

Max