Re: [RESEND][PATCH] Add /proc/mempool to display mempool usage

["Pekka Enberg" <penberg@cs.helsinki.fi>]

On Mon, Dec 1, 2008 at 10:02 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Mon, 01 Dec 2008 13:13:31 -0600
> Matt Mackall <mpm@selenic.com> wrote:
>
>> On Mon, 2008-12-01 at 10:12 -0800, Randy Dunlap wrote:
>> > On Sat, 29 Nov 2008 15:49:07 -0800 Greg KH wrote:
>> >
>> > > On Sun, Nov 30, 2008 at 12:42:07AM +0300, Alexey Dobriyan wrote:
>> > > > On Sat, Nov 29, 2008 at 06:44:49PM +0100, Remi Colinet wrote:
>> > > > > This patch add a new /proc/mempool file in order to display mempool usage.
>> > > > >
>> > > > > The feature can be disabled with CONFIG_PROC_MEMPOOL=N during kernel
>> > > > > configuration.
>> > > >
>> > > > We're NOT adding config option per proc file.
>> > > >
>> > > > And can we, please, freeze /proc for not per-process stuff and open debugfs
>> > > > for random stuff, please?
>> > >
>> > > debugfs has been open for random stuff since the day it was added to the
>> > > tree :)
>> > >
>> > > Feel free to put this kind of thing there instead of proc.
>> >
>> > Do distros ship with debugfs enabled?
>> > The problem with using debugfs is that it is very optional IMO.
>>
>> The problem with debugfs is that it claims to not be an ABI but it is
>> lying. Distributions ship tools that depend on portions of debugfs. And
>> they also ship debugfs in their kernel. So it is effectively the same
>> as /proc, except with the 1.0-era everything-goes attitude rather than
>> the 2.6-era we-should-really-think-about-this one.
>>
>> Pushing stuff from procfs to debugfs is thus just setting us up for pain
>> down the road. Don't do it. In five years, we'll discover we can't turn
>> debugfs off or even clean it up because too much relies on it.
>>
>> If you think that debugfs is NOT an ABI, then I'm sure you'll be happy
>> to ack my patch entitled 'gratuitously break usbmon to remind folks that
>> debugfs is not an ABI'.
>
> ^^ yup.

Hmm, I thought Documentation/ABI/ was supposed to tell us what's an
ABI you can depend on and what's not. I mean, you shouldn't be
depending on anything but the interfaces documented in
Documentation/ABI/stable/, no?