Re: Pls apply this spinlock patch to the kernel

[Anton Blanchard]

Hi,

> spinlock_t pagecache_lock ____cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
> cache_line_pad;
> 
> where cache_line_pad is an asm(".align") - I would assume that is
> sufficient - Linus ?

In include/asm-ppc64/cache.h I ended up redefining ____cacheline_aligned_in_smp
to avoid the problem of things sharing a cacheline: 

#ifdef CONFIG_SMP
#define ____cacheline_aligned_in_smp __cacheline_aligned
#else
#define ____cacheline_aligned_in_smp
#endif /* CONFIG_SMP */

so that these things end up in the cacheline_aligned section and no variables
share a cacheline. Maybe there are some places where we want to group
variables in the same cacheline, but for consistency I think we should
have:

__cacheline_aligned{,_in_smp}
	variable goes into cacheline_aligned section

____cacheline_aligned{,_in_smp}
	just align to a cacheline

Anton