Re: [PATCH v2] mm: add lazyfree folio to lru tail

[Barry Song <21cnbao@gmail.com>]

On Fri, Aug 16, 2024 at 7:48 PM gaoxu <gaoxu2@honor.com> wrote:
>
> Replace lruvec_add_folio with lruvec_add_folio_tail in the lru_lazyfree_fn:
> 1. The lazy-free folio is added to the LRU_INACTIVE_FILE list. If it's
>    moved to the LRU tail, it allows for faster release lazy-free folio and
>    reduces the impact on file refault.
> 2. When mglru is enabled, the lazy-free folio is reclaimabled and should be
>    added using lru_gen_add_folio(lruvec, folio, true) instead of
>    lru_gen_add_folio(lruvec, folio, false) for adding to gen.
>
> With the change in place, workingset_refault_file is reduced by 33% in the
> continuous startup testing of the applications in the Android system.
>

Hi Gao,

Just curious, in which scenario are we frequently calling
MADV_FREE but not MADV_DONTNEED?

> Signed-off-by: gao xu <gaoxu2@hihonor.com>
> ---
> V1 -> V2: Based on the latest mm-unstable, recreate the patch.
>
>  mm/swap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/swap.c b/mm/swap.c
> index 6b838986d..e0dbfc983 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -641,7 +641,7 @@ static void lru_lazyfree(struct lruvec *lruvec, struct folio *folio)
>          * anonymous folios
>          */
>         folio_clear_swapbacked(folio);
> -       lruvec_add_folio(lruvec, folio);
> +       lruvec_add_folio_tail(lruvec, folio);
>
>         __count_vm_events(PGLAZYFREE, nr_pages);
>         __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE, nr_pages);
> --
> 2.17.1