linux-kernel - Re: Bloatwatch 2.6.28-rc1: i8042 DMI lookup tables

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Date:	Fri, 24 Oct 2008 18:13:22 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: Bloatwatch 2.6.28-rc1: i8042 DMI lookup tables

On Sat, 2008-10-25 at 00:15 +0200, Jiri Kosina wrote:
> On Fri, 24 Oct 2008, Matt Mackall wrote:
> 
> > We've added 12k of new initdata to allnoconfig builds for i8042 DMI
> > lookup tables:
> > 
> > http://www.selenic.com/bloatwatch/?cmd=compare;v1=2.6.27;v2=2.6.28-rc1;part=/built-in/drivers
> > 
> > It looks like each table entry is > 320 bytes as we reserve four 80-byte
> > slots in each for DMI match strings. 
> 
> Umm, and what is the actual problem with that, really?

The actual problem is that if the kernel grows by 12k every time a
developer says "what's the big deal?" the kernel will become very large
indeed.

> OK, we can remove it from .init, but then it will be rotting in memory 
> forever, which is quite sub-optimal, when this kind of DMI information is 
> needed only during initialization.

I wasn't complaining that they were in init, but rather that they were
12k. For something like 37 entries. The entry size is ridiculous and
looks to have grown by a factor of 10 since 2.6.27. What, as they say,
is up with that?

It looks like David Woodhouse is to blame:

commit d945b697d0eea5a811ec299c5f1a25889bb0242b
Automatic MODULE_ALIAS() for DMI match tables.

This is probably also responsible for most of the growth in x86 I
mentioned elsewhere, so it's about 25-30k damage in total. David?

-- 
Mathematics is the supreme nostalgia of our time.

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