Re: [PATCH 64 of 66] scale nr_rotated to balance memory pressure

KOSAKI Motohiro
2010-11-09T06:16:27Z

> From: Rik van Riel <riel@redhat.com>
>
> Make sure we scale up nr_rotated when we encounter a referenced
> transparent huge page. This ensures pageout scanning balance
> is not distorted when there are huge pages on the LRU.
>
> Signed-off-by: Rik van Riel <riel@redhat.com>
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> ---
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1259,7 +1259,8 @@ putback_lru_pages(struct zone *zone, str
> add_page_to_lru_list(zone, page, lru);
> if (is_active_lru(lru)) {
> int file = is_file_lru(lru);
> - reclaim_stat->recent_rotated[file]++;
> + int numpages = hpage_nr_pages(page);
> + reclaim_stat->recent_rotated[file] += numpages;
> }
> if (!pagevec_add(&pvec, page)) {
> spin_unlock_irq(&zone->lru_lock);

I haven't seen this patch series carefully yet. So, probably
my question is dumb. Why don't we need to change ->recent_scanned[] too?

> @@ -1535,7 +1536,7 @@ static void shrink_active_list(unsigned
> }
>
> if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
> - nr_rotated++;
> + nr_rotated += hpage_nr_pages(page);
> /*
> * Identify referenced, file-backed active pages and
> * give them one more trip around the active list. So