Re: [patch 1/5] i386 generic cmpxchg

[Zwane Mwaikambo <zwane@arm.linux.org.uk>]

On Mon, 31 Oct 2005, Nick Piggin wrote:

> Zwane Mwaikambo wrote:
> > Hi Nick,
> > 
> > On Sun, 30 Oct 2005, Nick Piggin wrote:
> > 
> > +#define cmpxchg(ptr,o,n)						\
> > +({									\
> > +	__typeof__(*(ptr)) __ret;					\
> > +	if (likely(boot_cpu_data.x86 > 3))				\
> > +		__ret = __cmpxchg((ptr), (unsigned long)(o),		\
> > +					(unsigned long)(n), sizeof(*(ptr))); \
> > +	else								\
> > +		__ret = cmpxchg_386((ptr), (unsigned long)(o),		\
> > +					(unsigned long)(n), sizeof(*(ptr))); \
> > +	__ret;								\
> > +})
> > +#endif
> > 
> > How about something similar to the following to remove the branch on
> > optimised kernels?
> > 
> 
> This is only in the !CONFIG_X86_CMPXCHG case, though, so the branch would
> only be there on a 386 kernel, I think?

Ah yes you are right, i missed the #else.

Thanks,
	Zwane

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