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SubjectRe: [PATCH v5 02/14] mm/damon: Implement region based sampling
Date
On Mon, 17 Feb 2020 11:25:32 +0100 SeongJae Park <sjpark@amazon.com> wrote:

> From: SeongJae Park <sjpark@amazon.de>
>
> This commit implements DAMON's basic access check and region based
> sampling mechanisms. This change would seems make no sense, mainly
> because it is only a part of the DAMON's logics. Following two commits
> will make more sense.
>
[...]
> +/*
> + * Check whether the given region has accessed since the last check
> + *
> + * mm 'mm_struct' for the given virtual address space
> + * r the region to be checked
> + */
> +static void kdamond_check_access(struct damon_ctx *ctx,
> + struct mm_struct *mm, struct damon_region *r)
> +{
> + pte_t *pte = NULL;
> + pmd_t *pmd = NULL;
> + spinlock_t *ptl;
> +
> + if (follow_pte_pmd(mm, r->sampling_addr, NULL, &pte, &pmd, &ptl))
> + goto mkold;
> +
> + /* Read the page table access bit of the page */
> + if (pte && pte_young(*pte))
> + r->nr_accesses++;
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + else if (pmd && pmd_young(*pmd))
> + r->nr_accesses++;
> +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> +
> + spin_unlock(ptl);
> +
> +mkold:
> + /* mkold next target */
> + r->sampling_addr = damon_rand(ctx, r->vm_start, r->vm_end);
> +
> + if (follow_pte_pmd(mm, r->sampling_addr, NULL, &pte, &pmd, &ptl))
> + return;
> +
> + if (pte) {
> + if (pte_young(*pte)) {
> + clear_page_idle(pte_page(*pte));
> + set_page_young(pte_page(*pte));
> + }
> + *pte = pte_mkold(*pte);
> + }
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + else if (pmd) {
> + if (pmd_young(*pmd)) {
> + clear_page_idle(pmd_page(*pmd));
> + set_page_young(pte_page(*pte));

Oops, This should be `set_page_young(pmd_page(*pmd))`. Will fix in next spin.


Thanks,
SeongJae Park

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