Re: [Xen-ia64-devel] [PATCH] add volatile to pte entry of the p2m table

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

Hi Alex.

On Fri, Jun 09, 2006 at 11:06:52AM -0600, Alex Williamson wrote:
> On Fri, 2006-06-09 at 18:16 +0900, Isaku Yamahata wrote:
> > add volatile to pte entry of the p2m table.
> > p2m table are shared by cpu. added volatile as compiler barrier.
> 
>    Are all of these really needed?  Seems a little overkill to me.

Actually no.
assign_new_domain_page() and its families and domain_page_mapped()
are used only when domain construction (for now).
So their pte accesses aren't racy.

However, to remove volatile of them, non-volatile version
of lookup_alloc_domain_pte() is needed.
Because domain creation isn't performance critical,
I did't think it was worthwhile to both volatile version
and non-volatile version of lookup_alloc_domain_pte().

Scattering volatile is very ugly and I don't have any reason 
to stick to add volatile to assing_new_domain_page() and its variants.
If you prefer, I'll remove volatile of them.

-- 
yamahata

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