Re: [PATCH v1 9/9] mm/memory: optimize unmap/zap with PTE-mapped THP

[Yin Fengwei]

On 1/29/24 22:32, David Hildenbrand wrote:
> +static inline pte_t get_and_clear_full_ptes(struct mm_struct *mm,
> +             unsigned long addr, pte_t *ptep, unsigned int nr, int full)
> +{
> +     pte_t pte, tmp_pte;
> +
> +     pte = ptep_get_and_clear_full(mm, addr, ptep, full);
> +     while (--nr) {
> +             ptep++;
> +             addr += PAGE_SIZE;
> +             tmp_pte = ptep_get_and_clear_full(mm, addr, ptep, full);
> +             if (pte_dirty(tmp_pte))
> +                     pte = pte_mkdirty(pte);
> +             if (pte_young(tmp_pte))
> +                     pte = pte_mkyoung(pte);
I am wondering whether it's worthy to move the pte_mkdirty() and pte_mkyoung()
out of the loop and just do it one time if needed. The worst case is that they
are called nr - 1 time. Or it's just too micro?


Regards
Yin, Fengwei

> +     }
> +     return pte;
> +}