Re: [RFC][PATCH 6/9] mm/vmscan: add page demotion counter

Huang, Ying
2020-10-19T07:38:03Z

Dave Hansen <dave.hansen@linux.intel.com> writes:

> From: Yang Shi <yang.shi@linux.alibaba.com>
>
> Account the number of demoted pages into reclaim_state->nr_demoted.

It appears that you don't add "nr_demoted" into struct reclaim_state.

> 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()

It appears that we get the data from migrate_pages() now.

> ]
>
> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: David Hildenbrand <david@redhat.com>
> ---
>
> b/include/linux/vm_event_item.h | 2 ++
> b/mm/vmscan.c | 6 ++++++
> b/mm/vmstat.c | 2 ++
> 3 files changed, 10 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 2020-10-07 09:15:32.171642439 -0700
> +++ b/include/linux/vm_event_item.h 2020-10-07 09:15:32.179642439 -0700
> @@ -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 2020-10-07 09:15:32.173642439 -0700
> +++ b/mm/vmscan.c 2020-10-07 09:15:32.180642439 -0700
> @@ -147,6 +147,7 @@ struct scan_control {
> unsigned int immediate;
> unsigned int file_taken;
> unsigned int taken;
> + unsigned int demoted;

It appears that this newly added field isn't used in the patch.

> } nr;
>
> /* for recording the reclaimed slab by now */
> @@ -1134,6 +1135,11 @@ 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 2020-10-07 09:15:32.175642439 -0700
> +++ b/mm/vmstat.c 2020-10-07 09:15:32.181642439 -0700
> @@ -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",
> _

Best Regards,
Huang, Ying