Re: RFC: remove __read_mostly

[Eric Dumazet <dada1@cosmosbay.com>]

Matt Mackall a écrit :
> On Thu, Dec 13, 2007 at 11:20:44PM +0100, Adrian Bunk wrote:
>   
> > I tried the following patch with a full x86 .config [1]:
> >
> > --- a/include/asm-x86/cache.h
> > +++ b/include/asm-x86/cache.h
> > -#define __read_mostly __attribute__((__section__(".data.read_mostly")))
> > +/* #define __read_mostly __attribute__((__section__(".data.read_mostly"))) */
> >
> > The result [2,3] was:
> >
> > -rwxrwxr-x 1 bunk bunk 46607243 2007-12-13 19:50 vmlinux.old
> > -rwxrwxr-x 1 bunk bunk 46598691 2007-12-13 21:55 vmlinux
> >
> > It's not a surprise that the kernel can become bigger when __read_mostly 
> > gets used, especially in cases where __read_mostly prevents gcc 
> > optimizations.
> >
> > My question is:
> > Is there anywhere in the kernel a case where __read_mostly brings a 
> > measurable improvement or can it be removed?
> >     
>
> Yes, but perhaps we can put it under CONFIG_BASE_FULL?
>
>   
Yes, we probably can do something like that (in addition to !CONFIG_SMP)





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