[Xen-devel] Re: My turn to rant about types... bitops

[Andi Kleen <ak@xxxxxxx>]

Jimi Xenidis <jimix@xxxxxxxxxxxxxx> writes:
> 
> The next request is really the jist of what we are after, doing 64bit
> operations 32bit aligned data kills us performance wise and WRT
> bitops cannot be used for atomic ops. If htis was just Xen I'd
> consider adding 32bit bitops but I doubt I'd be able to do that in
> Linux which does not provide "u32" bitops.

Actually it does - when the arch has ARCH_HAS_ATOMIC_UNSIGNED set
it's allowed with the normal bitops.
 
> IIRC assuring this alignement would even help x86, no?

I doubt it (unless you're straddling a cache line) 

-Andi

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