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mm, vmscan: do not count freed pages as PGDEACTIVATE

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PGDEACTIVATE represents the number of pages moved from the active list
to the inactive list.  At least this sounds like the original motivation
of the counter.  move_active_pages_to_lru, however, counts pages which
got freed in the mean time as deactivated as well.  This is a very rare
event and counting them as deactivation in itself is not harmful but it
makes the code more convoluted than necessary - we have to count both
all pages and those which are freed which is a bit confusing.

After this patch the PGDEACTIVATE should have a slightly more clear
semantic and only count those pages which are moved from the active to
the inactive list which is a plus.

Link: http://lkml.kernel.org/r/20170112211221.17636-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2017-02-22 15:45:55 -08:00 committed by Linus Torvalds
parent bc71226b06
commit f0958906cd
1 changed files with 1 additions and 3 deletions
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4
mm/vmscan.c
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@ -1878,7 +1878,6 @@ static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
enum lru_list lru)
{
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
unsigned long pgmoved = 0;
struct page *page;
int nr_pages;
int nr_moved = 0;
@ -1893,7 +1892,6 @@ static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
nr_pages = hpage_nr_pages(page);
update_lru_size(lruvec, lru, page_zonenum(page), nr_pages);
list_move(&page->lru, &lruvec->lists[lru]);
pgmoved += nr_pages;
if (put_page_testzero(page)) {
__ClearPageLRU(page);
@ -1913,7 +1911,7 @@ static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
}
if (!is_active_lru(lru))
__count_vm_events(PGDEACTIVATE, pgmoved);
__count_vm_events(PGDEACTIVATE, nr_moved);
return nr_moved;
}