From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm, vmscan: do not count freed pages as PGDEACTIVATE 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@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Suggested-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmscan.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff -puN mm/vmscan.c~mm-vmscan-do-not-count-freed-pages-as-pgdeactivate mm/vmscan.c --- a/mm/vmscan.c~mm-vmscan-do-not-count-freed-pages-as-pgdeactivate +++ a/mm/vmscan.c @@ -1878,7 +1878,6 @@ static unsigned move_active_pages_to_lru 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 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 } if (!is_active_lru(lru)) - __count_vm_events(PGDEACTIVATE, pgmoved); + __count_vm_events(PGDEACTIVATE, nr_moved); return nr_moved; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
