Re: page fault scalability patch V14 [5/7]: x86_64 atomic pteoperations

[Christoph Lameter]

On Tue, 4 Jan 2005, Andi Kleen wrote:

> Christoph Lameter <clameter@xxxxxxx> writes:
>
> I bet this has been never tested.

I tested this back in October and it worked fine. Would you be able to
test your proposed modifications and send me a patch?

> > +#define pmd_test_and_populate(mm, pmd, pte) \
> > +		(cmpxchg((int *)pmd, PMD_NONE, _PAGE_TABLE | __pa(pte)) == PMD_NONE)
> > +#define pud_test_and_populate(mm, pud, pmd) \
> > +		(cmpxchg((int *)pgd, PUD_NONE, _PAGE_TABLE | __pa(pmd)) == PUD_NONE)
> > +#define pgd_test_and_populate(mm, pgd, pud) \
> > +		(cmpxchg((int *)pgd, PGD_NONE, _PAGE_TABLE | __pa(pud)) == PGD_NONE)
> > +
>
> Shouldn't this all be (long *)pmd ? page table entries on x86-64 are 64bit.
> Also why do you cast at all? i think the macro should handle an arbitary
> pointer.

The macro checks for the size of the pointer and then generates the
appropriate cmpxchg instruction. pgd_t is a struct which may be
problematic for the cmpxchg macros.
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