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Date:   Tue, 8 Jan 2019 02:49:01 +0300
From:   Alexey Dobriyan <adobriyan@gmail.com>
To:     Daniel Colascione <dancol@google.com>
Cc:     Dave Chinner <david@fromorbit.com>,
        Waiman Long <longman@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Jonathan Corbet <corbet@lwn.net>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH 0/2] /proc/stat: Reduce irqs counting performance overhead
Message-ID: <20190107234901.GA27074@avx2>
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On Mon, Jan 07, 2019 at 05:41:28PM -0500, Daniel Colascione wrote:
> There should be a general-purpose way for /proc file readers to tell
> the kernel which bits of information interest them on a particular read
> syscall sequence or particular open(2) or something.

This opens a pandora box full of ioctls. /proc supports ioctls on files
which aren't /proc/$PID and /proc/sys/* though.

So people made a mess with allegedly easy text files and now they
continue to make even more mess adding ioctls on top.