Re: [patch 1/2] i386: use asm() like the other atomic operations already do.

From: Herbert Xu
Date: Wed Aug 15 2007 - 19:44:59 EST


On Wed, Aug 15, 2007 at 01:02:23PM -0400, Chris Snook wrote:
> Herbert Xu wrote:
> >Andi Kleen <ak@xxxxxxx> wrote:
> >>>My config with march=pentium-m and gcc (GCC) 4.1.2 (Gentoo 4.1.2):
> >>> text data bss dec hex filename
> >>>3434150 249176 176128 3859454 3ae3fe atomic_normal/vmlinux
> >>>3435308 249176 176128 3860612 3ae884 atomic_inlineasm/vmlinux
> >>What is the difference between atomic_normal and atomic_inlineasm?
> >
> >The inline asm stops certain optimisations from occuring.
> >
> >I'm still unconvinced why we need this because nobody has
> >brought up any examples of kernel code that legitimately
> >need this.
>
> There's plenty of kernel code that *wants* this though. If we can

You keep saying this yet everytime I ask for an example I
get nothing.

> reduce the need for register-clobbering barriers, shrink our binaries,
> shrink our code, improve performance, and avoid heisenbugs, I think it's
> a win, whether or not we *need* it.

Hmm, you're increasing our binary size and probably killing
performance.

Cheers,
--
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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