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Re: [PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a partial scan"

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a partial scan"
Date 2017-03-01 17:00 +0100
Message-ID <tgePx-5b2-49@gated-at.bofh.it> (permalink)
References <tfZQt-2Vc-9@gated-at.bofh.it> <tg00a-3dN-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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@cmpxchg.org>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  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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Thread

[PATCH 0/9] mm: kswapd spinning on unreclaimable nodes - fixes and cleanups Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 01:00 +0100
  [PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 01:10 +0100
    Re: [PATCH 4/9] mm: remove unnecessary reclaimability check from  NUMA balancing target Michal Hocko <mhocko@kernel.org> - 2017-03-01 20:30 +0100
    Re: [PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:40 +0100
  [PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a partial scan" Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 01:10 +0100
    Re: [PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a  partial scan" Michal Hocko <mhocko@kernel.org> - 2017-03-01 17:00 +0100
  [PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
    Re: [PATCH 3/9] mm: remove seemingly spurious reclaimability check  from laptop_mode gating Mel Gorman <mgorman@suse.de> - 2017-03-01 16:20 +0100
    Re: [PATCH 3/9] mm: remove seemingly spurious reclaimability check  from laptop_mode gating Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:50 +0100
    Re: [PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:30 +0100
  [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
    Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit  reclaim Michal Hocko <mhocko@kernel.org> - 2017-03-01 17:00 +0100
      Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit  reclaim Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 19:30 +0100
        Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit  reclaim Michal Hocko <mhocko@kernel.org> - 2017-03-01 20:20 +0100
    Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:40 +0100
  [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
    Re: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC  reclaim throttling Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:10 +0100
    Re: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:30 +0100
  [PATCH 7/9] mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
    Re: [PATCH 7/9] mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:50 +0100
  [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
    Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:30 +0100
    Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Shakeel Butt <shakeelb@google.com> - 2017-03-03 02:40 +0100
    Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Minchan Kim <minchan@kernel.org> - 2017-03-03 02:50 +0100
      Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Michal Hocko <mhocko@kernel.org> - 2017-03-03 09:10 +0100
        Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Minchan Kim <minchan@kernel.org> - 2017-03-06 02:40 +0100
          Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-06 17:40 +0100
            Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-07 02:10 +0100
            Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Minchan Kim <minchan@kernel.org> - 2017-03-07 08:50 +0100
            Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Michal Hocko <mhocko@kernel.org> - 2017-03-07 11:30 +0100
              Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-07 20:00 +0100
                Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable  nodes Mel Gorman <mgorman@suse.de> - 2017-03-09 15:40 +0100
  [PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 15:00 +0100
    Re: [PATCH 9/9] mm: remove unnecessary back-off function when  retrying page reclaim Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:50 +0100
  [PATCH 5/9] mm: don't avoid high-priority reclaim on unreclaimable nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 15:00 +0100
    Re: [PATCH 5/9] mm: don't avoid high-priority reclaim on  unreclaimable nodes Michal Hocko <mhocko@kernel.org> - 2017-03-01 17:00 +0100

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