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

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Message-ID: <CAGsJ_4xTW5y4O6BoVuXKk=awhoiZV0zitPYYbfsX1pmqZgY9WQ@mail.gmail.com>
Date: Tue, 20 Aug 2024 22:11:23 +1200
From: Barry Song <21cnbao@...il.com>
To: gaoxu <gaoxu2@...or.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Suren Baghdasaryan <surenb@...gle.com>, 
	Shaohua Li <shli@...com>, yipengxiang <yipengxiang@...or.com>, fengbaopeng <fengbaopeng@...or.com>, 
	Kalesh Singh <kaleshsingh@...gle.com>
Subject: Re: [PATCH v2] mm: add lazyfree folio to lru tail

On Fri, Aug 16, 2024 at 7:48 PM gaoxu <gaoxu2@...or.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@...onor.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