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Groups > linux.kernel > #1550637

[PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct
Date 2017-01-04 11:30 +0100
Message-ID <sVQZs-3pc-39@gated-at.bofh.it> (permalink)
References <sVQZr-3pc-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Michal Hocko <mhocko@suse.com>

shrink_page_list returns quite some counters back to its caller. Extract
the existing 5 into struct reclaim_stat because this makes the code
easier to follow and also allows further counters to be returned.

While we are at it, make all of them unsigned rather than unsigned long
as we do not really need full 64b for them (we never scan more than
SWAP_CLUSTER_MAX pages at once). This should reduce some stack space.

This patch shouldn't introduce any functional change.

Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 61 ++++++++++++++++++++++++++++++-------------------------------
 1 file changed, 30 insertions(+), 31 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 13758aaed78b..920e47a905c3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -902,6 +902,14 @@ static void page_check_dirty_writeback(struct page *page,
 		mapping->a_ops->is_dirty_writeback(page, dirty, writeback);
 }
 
+struct reclaim_stat {
+	unsigned nr_dirty;
+	unsigned nr_unqueued_dirty;
+	unsigned nr_congested;
+	unsigned nr_writeback;
+	unsigned nr_immediate;
+};
+
 /*
  * shrink_page_list() returns the number of reclaimed pages
  */
@@ -909,22 +917,18 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 				      struct pglist_data *pgdat,
 				      struct scan_control *sc,
 				      enum ttu_flags ttu_flags,
-				      unsigned long *ret_nr_dirty,
-				      unsigned long *ret_nr_unqueued_dirty,
-				      unsigned long *ret_nr_congested,
-				      unsigned long *ret_nr_writeback,
-				      unsigned long *ret_nr_immediate,
+				      struct reclaim_stat *stat,
 				      bool force_reclaim)
 {
 	LIST_HEAD(ret_pages);
 	LIST_HEAD(free_pages);
 	int pgactivate = 0;
-	unsigned long nr_unqueued_dirty = 0;
-	unsigned long nr_dirty = 0;
-	unsigned long nr_congested = 0;
-	unsigned long nr_reclaimed = 0;
-	unsigned long nr_writeback = 0;
-	unsigned long nr_immediate = 0;
+	unsigned nr_unqueued_dirty = 0;
+	unsigned nr_dirty = 0;
+	unsigned nr_congested = 0;
+	unsigned nr_reclaimed = 0;
+	unsigned nr_writeback = 0;
+	unsigned nr_immediate = 0;
 
 	cond_resched();
 
@@ -1266,11 +1270,13 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 	list_splice(&ret_pages, page_list);
 	count_vm_events(PGACTIVATE, pgactivate);
 
-	*ret_nr_dirty += nr_dirty;
-	*ret_nr_congested += nr_congested;
-	*ret_nr_unqueued_dirty += nr_unqueued_dirty;
-	*ret_nr_writeback += nr_writeback;
-	*ret_nr_immediate += nr_immediate;
+	if (stat) {
+		stat->nr_dirty = nr_dirty;
+		stat->nr_congested = nr_congested;
+		stat->nr_unqueued_dirty = nr_unqueued_dirty;
+		stat->nr_writeback = nr_writeback;
+		stat->nr_immediate = nr_immediate;
+	}
 	return nr_reclaimed;
 }
 
@@ -1282,7 +1288,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
 		.priority = DEF_PRIORITY,
 		.may_unmap = 1,
 	};
-	unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;
+	unsigned long ret;
 	struct page *page, *next;
 	LIST_HEAD(clean_pages);
 
@@ -1295,8 +1301,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
 	}
 
 	ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc,
-			TTU_UNMAP|TTU_IGNORE_ACCESS,
-			&dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
+			TTU_UNMAP|TTU_IGNORE_ACCESS, NULL, true);
 	list_splice(&clean_pages, page_list);
 	mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret);
 	return ret;
@@ -1696,11 +1701,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	unsigned long nr_scanned;
 	unsigned long nr_reclaimed = 0;
 	unsigned long nr_taken;
-	unsigned long nr_dirty = 0;
-	unsigned long nr_congested = 0;
-	unsigned long nr_unqueued_dirty = 0;
-	unsigned long nr_writeback = 0;
-	unsigned long nr_immediate = 0;
+	struct reclaim_stat stat = {};
 	isolate_mode_t isolate_mode = 0;
 	int file = is_file_lru(lru);
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
@@ -1745,9 +1746,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		return 0;
 
 	nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, TTU_UNMAP,
-				&nr_dirty, &nr_unqueued_dirty, &nr_congested,
-				&nr_writeback, &nr_immediate,
-				false);
+				&stat, false);
 
 	spin_lock_irq(&pgdat->lru_lock);
 
@@ -1781,7 +1780,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	 * of pages under pages flagged for immediate reclaim and stall if any
 	 * are encountered in the nr_immediate check below.
 	 */
-	if (nr_writeback && nr_writeback == nr_taken)
+	if (stat.nr_writeback && stat.nr_writeback == nr_taken)
 		set_bit(PGDAT_WRITEBACK, &pgdat->flags);
 
 	/*
@@ -1793,7 +1792,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		 * Tag a zone as congested if all the dirty pages scanned were
 		 * backed by a congested BDI and wait_iff_congested will stall.
 		 */
-		if (nr_dirty && nr_dirty == nr_congested)
+		if (stat.nr_dirty && stat.nr_dirty == stat.nr_congested)
 			set_bit(PGDAT_CONGESTED, &pgdat->flags);
 
 		/*
@@ -1802,7 +1801,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		 * the pgdat PGDAT_DIRTY and kswapd will start writing pages from
 		 * reclaim context.
 		 */
-		if (nr_unqueued_dirty == nr_taken)
+		if (stat.nr_unqueued_dirty == nr_taken)
 			set_bit(PGDAT_DIRTY, &pgdat->flags);
 
 		/*
@@ -1811,7 +1810,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		 * that pages are cycling through the LRU faster than
 		 * they are written so also forcibly stall.
 		 */
-		if (nr_immediate && current_may_throttle())
+		if (stat.nr_immediate && current_may_throttle())
 			congestion_wait(BLK_RW_ASYNC, HZ/10);
 	}
 
-- 
2.11.0

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[PATCH 0/7 v2] vm, vmscan: enahance vmscan tracepoints Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
  [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
    Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Vlastimil Babka <vbabka@suse.cz> - 2017-01-04 14:10 +0100
      Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-04 14:20 +0100
        Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Vlastimil Babka <vbabka@suse.cz> - 2017-01-04 14:50 +0100
    Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-04 15:00 +0100
      Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Minchan Kim <minchan@kernel.org> - 2017-01-05 06:50 +0100
  [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
    Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Minchan Kim <minchan@kernel.org> - 2017-01-05 07:10 +0100
      Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-05 11:20 +0100
        Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Mel Gorman <mgorman@suse.de> - 2017-01-05 16:00 +0100
          Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-05 16:20 +0100
  [PATCH 3/7] mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
  [PATCH 6/7] mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
  [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
    Re: [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters  into a struct Vlastimil Babka <vbabka@suse.cz> - 2017-01-04 16:00 +0100
      Re: [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim  counters into a struct Michal Hocko <mhocko@kernel.org> - 2017-01-04 16:20 +0100
  [PATCH 7/7] mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:30 +0100
  Re: [PATCH 0/7 v2] vm, vmscan: enahance vmscan tracepoints Michal Hocko <mhocko@kernel.org> - 2017-01-04 11:40 +0100
  Re: [PATCH 0/7 v2] vm, vmscan: enahance vmscan tracepoints Vlastimil Babka <vbabka@suse.cz> - 2017-01-05 09:30 +0100
  Re: [PATCH 0/7 v2] vm, vmscan: enahance vmscan tracepoints Michal Hocko <mhocko@kernel.org> - 2017-01-05 11:50 +0100

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