On Wed, 21 Dec 2011 17:23:45 -0500
Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:
> Thp split is not necessary if we explicitly check whether pmds are
> mapping thps or not. This patch introduces the check and the code
> to generate pagemap entries for pmds mapping thps, which results in
> less performance impact of pagemap on thp.
>
>
> ...
The type choices seem odd:
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static u64 thp_pte_to_pagemap_entry(pte_t pte, int offset)
> +{
> + u64 pme = 0;
Why are these u64?
Should we have a pme_t, matching pte_t, pmd_t, etc?
> + if (pte_present(pte))
> + pme = PM_PFRAME(pte_pfn(pte) + offset)
> + | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
> + return pme;
> +}
> +#else
> +static inline u64 thp_pte_to_pagemap_entry(pte_t pte, int offset)
> +{
> + return 0;
> +}
> +#endif
> +
> static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> struct mm_walk *walk)
> {
> @@ -665,14 +684,34 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> struct pagemapread *pm = walk->private;
> pte_t *pte;
> int err = 0;
> -
> - split_huge_page_pmd(walk->mm, pmd);
> + u64 pfn = PM_NOT_PRESENT;
Again, why a u64? pfn's are usually unsigned long.
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