Messages in this thread | | | Date | Wed, 4 Jan 2012 15:50:42 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/4] pagemap: avoid splitting thp when reading /proc/pid/pagemap |
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On Wed, 21 Dec 2011 17:23:45 -0500 Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> 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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