linux-kernel - Re: [PATCH] mm: vmscan: consistent update to pgrefill

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Date:   Sat, 11 Jul 2020 09:54:28 +0800
From:   Yafang Shao <laoar.shao@...il.com>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     Johannes Weiner <hannes@...xchg.org>, Roman Gushchin <guro@...com>,
        Michal Hocko <mhocko@...nel.org>,
        Chris Down <chris@...isdown.name>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: vmscan: consistent update to pgrefill

On Sat, Jul 11, 2020 at 9:15 AM Shakeel Butt <shakeelb@...gle.com> wrote:
>
> The vmstat pgrefill is useful together with pgscan and pgsteal stats to
> measure the reclaim efficiency. However vmstat's pgrefill is not updated
> consistently at system level. It gets updated for both global and memcg
> reclaim however pgscan and pgsteal are updated for only global reclaim.
> So, update pgrefill only for global reclaim. If someone is interested in
> the stats representing both system level as well as memcg level reclaim,
> then consult the root memcg's memory.stat instead of /proc/vmstat.
>
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>

Acked-by: Yafang Shao <laoar.shao@...il.com>

> ---
>  mm/vmscan.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 5215840ee217..4167b0cc1784 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2030,7 +2030,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
>
>         __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
>
> -       __count_vm_events(PGREFILL, nr_scanned);
> +       if (!cgroup_reclaim(sc))
> +               __count_vm_events(PGREFILL, nr_scanned);
>         __count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
>
>         spin_unlock_irq(&pgdat->lru_lock);
> --
> 2.27.0.383.g050319c2ae-goog
>


-- 
Thanks
Yafang