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From: Sam Ravnborg <sam@ravnborg.org>
To: Ingo Molnar <mingo@elte.hu>, Christopher Li <sparse@chrisli.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	David Miller <davem@davemloft.net>,
	linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
	x86@kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [bloat] Measuring header file bloat effects on kernel build performance: a more than 2x slowdown ...
Date: Mon, 23 May 2011 18:19:14 +0200	[thread overview]
Message-ID: <20110523161914.GA15464@merkur.ravnborg.org> (raw)
In-Reply-To: <20110523090918.GA5474@elte.hu>

> 
> 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

  parent reply	other threads:[~2011-05-23 16:19 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-20  6:12 linux-next: build failure after merge of the final tree Stephen Rothwell
2011-05-20 15:24 ` Linus Torvalds
2011-05-20 16:16   ` Thomas Gleixner
2011-05-20 16:29     ` Linus Torvalds
2011-05-23  9:09   ` [bloat] Measuring header file bloat effects on kernel build performance: a more than 2x slowdown Ingo Molnar
2011-05-23 10:21     ` Alexey Dobriyan
2011-05-23 10:55       ` Ingo Molnar
2011-05-23 11:13         ` Alexey Dobriyan
2011-05-23 11:51           ` Ingo Molnar
2011-05-23 16:01     ` Linus Torvalds
2011-05-23 17:01       ` Ingo Molnar
2011-05-23 16:19     ` Sam Ravnborg [this message]
2011-05-28  0:36     ` Paul Gortmaker
2011-05-28 14:40       ` [PATCH] Fixes to the module.h splitup tree Ingo Molnar

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