Subject: Re: [bloat] Measuring header file bloat effects on kernel build performance: a more than 2x slowdown ...

From: Sam Ravnborg <[email-masked]>
Date: Mon, 23 May 2011 18:19:14 +0200

> 
> Such thing happen due to:
> 
>  - header files only get added, almost never removed
> 
> The key thing was that the build did not break when prefetch.h was kept 
> dangling. Not sure what to do about that - for humans a dangling header is 
> absolutely non-obvious to find - we'd need tooling help.

Long time ago I discussed this briefly with Christopher Li,
and he hacked support for this in sparse.

The branch is still around:

http://git.kernel.org/?p=devel/sparse/chrisl/sparse.git;a=shortlog;h=unused-include-files

I never got around to play with it for various reasons.
IIRC it will list include files not used in _current_ configuration,
so use if CONFIG_ etc. may give different results.

	Sam