[PATCH 02/14] mm: keep separate anon and file statistics on page reclaim activity

[Johannes Weiner]

Having statistics on pages scanned and pages reclaimed for both anon
and file pages makes it easier to evaluate changes to LRU balancing.

While at it, clean up the stat-keeping mess for isolation, putback,
reclaim stats etc. a bit: first the physical LRU operation (isolation
and putback), followed by vmstats, reclaim_stats, and then vm events.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 include/linux/vm_event_item.h |  4 ++++
 mm/vmscan.c                   | 17 +++++++++--------
 mm/vmstat.c                   |  4 ++++
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index ffef0f279747..24fc7c3ae7d6 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -35,6 +35,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		PGSCAN_KSWAPD,
 		PGSCAN_DIRECT,
 		PGSCAN_DIRECT_THROTTLE,
+		PGSCAN_ANON,
+		PGSCAN_FILE,
+		PGSTEAL_ANON,
+		PGSTEAL_FILE,
 #ifdef CONFIG_NUMA
 		PGSCAN_ZONE_RECLAIM_FAILED,
 #endif
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cc555903a332..70b0e2c6a4b9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1913,7 +1913,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	unsigned int nr_reclaimed = 0;
 	unsigned long nr_taken;
 	struct reclaim_stat stat;
-	int file = is_file_lru(lru);
+	bool file = is_file_lru(lru);
 	enum vm_event_item item;
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
@@ -1941,11 +1941,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 
 	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
 	reclaim_stat->recent_scanned[file] += nr_taken;
-
 	item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT;
 	if (!cgroup_reclaim(sc))
 		__count_vm_events(item, nr_scanned);
 	__count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
+	__count_vm_events(PGSCAN_ANON + file, nr_scanned);
+
 	spin_unlock_irq(&pgdat->lru_lock);
 
 	if (nr_taken == 0)
@@ -1956,16 +1957,16 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 
 	spin_lock_irq(&pgdat->lru_lock);
 
+	move_pages_to_lru(lruvec, &page_list);
+
+	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
+	reclaim_stat->recent_rotated[0] += stat.nr_activate[0];
+	reclaim_stat->recent_rotated[1] += stat.nr_activate[1];
 	item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT;
 	if (!cgroup_reclaim(sc))
 		__count_vm_events(item, nr_reclaimed);
 	__count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
-	reclaim_stat->recent_rotated[0] += stat.nr_activate[0];
-	reclaim_stat->recent_rotated[1] += stat.nr_activate[1];
-
-	move_pages_to_lru(lruvec, &page_list);
-
-	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
+	__count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
 
 	spin_unlock_irq(&pgdat->lru_lock);
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 4b0c90e4de71..3d06bd89d9ec 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1201,6 +1201,10 @@ const char * const vmstat_text[] = {
 	"pgscan_kswapd",
 	"pgscan_direct",
 	"pgscan_direct_throttle",
+	"pgscan_anon",
+	"pgscan_file",
+	"pgsteal_anon",
+	"pgsteal_file",
 
 #ifdef CONFIG_NUMA
 	"zone_reclaim_failed",
-- 
2.26.2