linux-kernel - Re: [rfc] the kernel workflow & trivial "global -> static" patches

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Message-ID: <20080506112505.GA2359@cs181133002.pp.htv.fi>
Date:	Tue, 6 May 2008 14:25:05 +0300
From:	Adrian Bunk <bunk@...nel.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Sam Ravnborg <sam@...nborg.org>,
	Alexander Viro <viro@....linux.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [rfc] the kernel workflow & trivial "global -> static" patches

On Tue, May 06, 2008 at 01:13:01PM +0200, Andi Kleen wrote:
> Adrian Bunk wrote:
> > On Tue, May 06, 2008 at 02:21:31AM +0200, Andi Kleen wrote:
>...
> >> I could see some advantage from static in future compiler versions 
> >> though from better optimization, but it's quite remote.
> >> ...
> > 
> > The best case I've actually seen in practice was a variable I made 
> > static, and with CONFIG_DEBUG_FOOBAR=n gcc was now able to prove that 
> > the value never changed resulting in the variable plus quite a chunk
> > of code no longer emitted.
> 
> Sounds like the variable should just have been removed then in the source?

No, an #ifdef CONFIG_DEBUG_FOOBAR guarded some sysctl that allows users 
to change the value.

(I'm not claiming this was a common case.)

> -Andi

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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