On Tue 28-02-17 16:40:06, Johannes Weiner wrote:
> This reverts commit d7f05528eedb047efe2288cff777676b028747b6.
>
> Now that reclaimability of a node is no longer based on the ratio
> between pages scanned and theoretically reclaimable pages, we can
> remove accounting tricks for pages skipped due to zone constraints.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/vmscan.c | 22 ++++------------------
> 1 file changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 35b791a8922b..ddcff8a11c1e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1471,12 +1471,12 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> unsigned long nr_taken = 0;
> unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
> unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
> - unsigned long skipped = 0, total_skipped = 0;
> + unsigned long skipped = 0;
> unsigned long scan, nr_pages;
> LIST_HEAD(pages_skipped);
>
> for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
> - !list_empty(src);) {
> + !list_empty(src); scan++) {
> struct page *page;
>
> page = lru_to_page(src);
> @@ -1490,12 +1490,6 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> continue;
> }
>
> - /*
> - * Account for scanned and skipped separetly to avoid the pgdat
> - * being prematurely marked unreclaimable by pgdat_reclaimable.
> - */
> - scan++;
> -
> switch (__isolate_lru_page(page, mode)) {
> case 0:
> nr_pages = hpage_nr_pages(page);
> @@ -1524,6 +1518,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> if (!list_empty(&pages_skipped)) {
> int zid;
>
> + list_splice(&pages_skipped, src);
> for (zid = 0; zid < MAX_NR_ZONES; zid++) {
> if (!nr_skipped[zid])
> continue;
> @@ -1531,17 +1526,8 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
> skipped += nr_skipped[zid];
> }
> -
> - /*
> - * Account skipped pages as a partial scan as the pgdat may be
> - * close to unreclaimable. If the LRU list is empty, account
> - * skipped pages as a full scan.
> - */
> - total_skipped = list_empty(src) ? skipped : skipped >> 2;
> -
> - list_splice(&pages_skipped, src);
> }
> - *nr_scanned = scan + total_skipped;
> + *nr_scanned = scan;
> trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
> scan, skipped, nr_taken, mode, lru);
> update_lru_sizes(lruvec, lru, nr_zone_taken);
> --
> 2.11.1
--
Michal Hocko
SUSE Labs
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