Re: [PATCH 06/10] mm/vmscan: add page demotion counter

[Yang Shi]

On Thu, Mar 4, 2021 at 4:01 PM Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> wrote:
>
>
> From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
>
> Account the number of demoted pages into reclaim_state->nr_demoted.
>
> Add pgdemote_kswapd and pgdemote_direct VM counters showed in
> /proc/vmstat.
>
> [ daveh:
>    - __count_vm_events() a bit, and made them look at the THP
>      size directly rather than getting data from migrate_pages()
> ]
>
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: osalvador <osalvador@xxxxxxx>
>
> --
>
> Changes since 202010:
>  * remove unused scan-control 'demoted' field

Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>

> ---
>
>  b/include/linux/vm_event_item.h |    2 ++
>  b/mm/vmscan.c                   |    5 +++++
>  b/mm/vmstat.c                   |    2 ++
>  3 files changed, 9 insertions(+)
>
> diff -puN include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter include/linux/vm_event_item.h
> --- a/include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter 2021-03-04 15:35:57.698806425 -0800
> +++ b/include/linux/vm_event_item.h     2021-03-04 15:35:57.719806425 -0800
> @@ -33,6 +33,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
>                 PGREUSE,
>                 PGSTEAL_KSWAPD,
>                 PGSTEAL_DIRECT,
> +               PGDEMOTE_KSWAPD,
> +               PGDEMOTE_DIRECT,
>                 PGSCAN_KSWAPD,
>                 PGSCAN_DIRECT,
>                 PGSCAN_DIRECT_THROTTLE,
> diff -puN mm/vmscan.c~mm-vmscan-add-page-demotion-counter mm/vmscan.c
> --- a/mm/vmscan.c~mm-vmscan-add-page-demotion-counter   2021-03-04 15:35:57.700806425 -0800
> +++ b/mm/vmscan.c       2021-03-04 15:35:57.724806425 -0800
> @@ -1118,6 +1118,11 @@ static unsigned int demote_page_list(str
>                             target_nid, MIGRATE_ASYNC, MR_DEMOTION,
>                             &nr_succeeded);
>
> +       if (current_is_kswapd())
> +               __count_vm_events(PGDEMOTE_KSWAPD, nr_succeeded);
> +       else
> +               __count_vm_events(PGDEMOTE_DIRECT, nr_succeeded);
> +
>         return nr_succeeded;
>  }
>
> diff -puN mm/vmstat.c~mm-vmscan-add-page-demotion-counter mm/vmstat.c
> --- a/mm/vmstat.c~mm-vmscan-add-page-demotion-counter   2021-03-04 15:35:57.708806425 -0800
> +++ b/mm/vmstat.c       2021-03-04 15:35:57.726806425 -0800
> @@ -1244,6 +1244,8 @@ const char * const vmstat_text[] = {
>         "pgreuse",
>         "pgsteal_kswapd",
>         "pgsteal_direct",
> +       "pgdemote_kswapd",
> +       "pgdemote_direct",
>         "pgscan_kswapd",
>         "pgscan_direct",
>         "pgscan_direct_throttle",
> _
>