[PATCH 6/7] mm/memcg: rework inactive_ratio calculation

[Konstantin Khlebnikov <khlebnikov@openvz.org>]

This patch removes precalculated zone->inactive_ratio.
Now it always calculated in inactive_anon_is_low() from current lru size.
After that we can merge memcg and non-memcg cases and drop duplicated code.

We can drop precalculated ratio, because its calculation fast enough to do it
each time. Plus precalculation uses zone size as basis, this estimation not
always match with page lru size, for example if a significant proportion
of memory occupied by kernel objects.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
---
 include/linux/memcontrol.h |   16 --------
 include/linux/mmzone.h     |    7 ----
 mm/memcontrol.c            |   38 -------------------
 mm/page_alloc.c            |   44 ----------------------
 mm/vmscan.c                |   88 ++++++++++++++++++++++++++++----------------
 mm/vmstat.c                |    6 +--
 6 files changed, 58 insertions(+), 141 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e2e1fac..7e114f8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -117,10 +117,6 @@ void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);
 /*
  * For memory reclaim.
  */
-int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg,
-				    struct zone *zone);
-int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg,
-				    struct zone *zone);
 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
 unsigned long mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg,
 					int nid, int zid, unsigned int lrumask);
@@ -334,18 +330,6 @@ static inline bool mem_cgroup_disabled(void)
 	return true;
 }
 
-static inline int
-mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
-{
-	return 1;
-}
-
-static inline int
-mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg, struct zone *zone)
-{
-	return 1;
-}
-
 static inline unsigned long
 mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
 				unsigned int lru_mask)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fdcd683..7edcf17 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -384,13 +384,6 @@ struct zone {
 	/* Zone statistics */
 	atomic_long_t		vm_stat[NR_VM_ZONE_STAT_ITEMS];
 
-	/*
-	 * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
-	 * this zone's LRU.  Maintained by the pageout code.
-	 */
-	unsigned int inactive_ratio;
-
-
 	ZONE_PADDING(_pad2_)
 	/* Rarely used or read-mostly fields */
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2809531..4bc6835 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1171,44 +1171,6 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
 	return ret;
 }
 
-int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
-{
-	unsigned long inactive_ratio;
-	int nid = zone_to_nid(zone);
-	int zid = zone_idx(zone);
-	unsigned long inactive;
-	unsigned long active;
-	unsigned long gb;
-
-	inactive = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
-						BIT(LRU_INACTIVE_ANON));
-	active = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
-					      BIT(LRU_ACTIVE_ANON));
-
-	gb = (inactive + active) >> (30 - PAGE_SHIFT);
-	if (gb)
-		inactive_ratio = int_sqrt(10 * gb);
-	else
-		inactive_ratio = 1;
-
-	return inactive * inactive_ratio < active;
-}
-
-int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg, struct zone *zone)
-{
-	unsigned long active;
-	unsigned long inactive;
-	int zid = zone_idx(zone);
-	int nid = zone_to_nid(zone);
-
-	inactive = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
-						BIT(LRU_INACTIVE_FILE));
-	active = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
-					      BIT(LRU_ACTIVE_FILE));
-
-	return (active > inactive);
-}
-
 struct zone_reclaim_stat *
 mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ea40034..2e90931 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5051,49 +5051,6 @@ void setup_per_zone_wmarks(void)
 }
 
 /*
- * The inactive anon list should be small enough that the VM never has to
- * do too much work, but large enough that each inactive page has a chance
- * to be referenced again before it is swapped out.
- *
- * The inactive_anon ratio is the target ratio of ACTIVE_ANON to
- * INACTIVE_ANON pages on this zone's LRU, maintained by the
- * pageout code. A zone->inactive_ratio of 3 means 3:1 or 25% of
- * the anonymous pages are kept on the inactive list.
- *
- * total     target    max
- * memory    ratio     inactive anon
- * -------------------------------------
- *   10MB       1         5MB
- *  100MB       1        50MB
- *    1GB       3       250MB
- *   10GB      10       0.9GB
- *  100GB      31         3GB
- *    1TB     101        10GB
- *   10TB     320        32GB
- */
-static void __meminit calculate_zone_inactive_ratio(struct zone *zone)
-{
-	unsigned int gb, ratio;
-
-	/* Zone size in gigabytes */
-	gb = zone->present_pages >> (30 - PAGE_SHIFT);
-	if (gb)
-		ratio = int_sqrt(10 * gb);
-	else
-		ratio = 1;
-
-	zone->inactive_ratio = ratio;
-}
-
-static void __meminit setup_per_zone_inactive_ratio(void)
-{
-	struct zone *zone;
-
-	for_each_zone(zone)
-		calculate_zone_inactive_ratio(zone);
-}
-
-/*
  * Initialise min_free_kbytes.
  *
  * For small machines we want it small (128k min).  For large machines
@@ -5131,7 +5088,6 @@ int __meminit init_per_zone_wmark_min(void)
 	setup_per_zone_wmarks();
 	refresh_zone_stat_thresholds();
 	setup_per_zone_lowmem_reserve();
-	setup_per_zone_inactive_ratio();
 	return 0;
 }
 module_init(init_per_zone_wmark_min)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fe00a22..ab447df 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1750,29 +1750,38 @@ static void shrink_active_list(unsigned long nr_to_scan,
 }
 
 #ifdef CONFIG_SWAP
-static int inactive_anon_is_low_global(struct zone *zone)
-{
-	unsigned long active, inactive;
-
-	active = zone_page_state(zone, NR_ACTIVE_ANON);
-	inactive = zone_page_state(zone, NR_INACTIVE_ANON);
-
-	if (inactive * zone->inactive_ratio < active)
-		return 1;
-
-	return 0;
-}
-
 /**
  * inactive_anon_is_low - check if anonymous pages need to be deactivated
  * @zone: zone to check
- * @sc:   scan control of this context
  *
  * Returns true if the zone does not have enough inactive anon pages,
  * meaning some active anon pages need to be deactivated.
+ *
+ * The inactive anon list should be small enough that the VM never has to
+ * do too much work, but large enough that each inactive page has a chance
+ * to be referenced again before it is swapped out.
+ *
+ * The inactive_anon ratio is the target ratio of ACTIVE_ANON to
+ * INACTIVE_ANON pages on this zone's LRU, maintained by the
+ * pageout code. A zone->inactive_ratio of 3 means 3:1 or 25% of
+ * the anonymous pages are kept on the inactive list.
+ *
+ * total     target    max
+ * memory    ratio     inactive anon
+ * -------------------------------------
+ *   10MB       1         5MB
+ *  100MB       1        50MB
+ *    1GB       3       250MB
+ *   10GB      10       0.9GB
+ *  100GB      31         3GB
+ *    1TB     101        10GB
+ *   10TB     320        32GB
  */
 static int inactive_anon_is_low(struct mem_cgroup_zone *mz)
 {
+	unsigned long active, inactive;
+	unsigned int gb, ratio;
+
 	/*
 	 * If we don't have swap space, anonymous page deactivation
 	 * is pointless.
@@ -1780,11 +1789,26 @@ static int inactive_anon_is_low(struct mem_cgroup_zone *mz)
 	if (!total_swap_pages)
 		return 0;
 
-	if (!mem_cgroup_disabled())
-		return mem_cgroup_inactive_anon_is_low(mz->mem_cgroup,
-						       mz->zone);
+	if (mem_cgroup_disabled()) {
+		active = zone_page_state(mz->zone, NR_ACTIVE_ANON);
+		inactive = zone_page_state(mz->zone, NR_INACTIVE_ANON);
+	} else {
+		active = mem_cgroup_zone_nr_lru_pages(mz->mem_cgroup,
+				zone_to_nid(mz->zone), zone_idx(mz->zone),
+				BIT(LRU_ACTIVE_ANON));
+		inactive = mem_cgroup_zone_nr_lru_pages(mz->mem_cgroup,
+				zone_to_nid(mz->zone), zone_idx(mz->zone),
+				BIT(LRU_INACTIVE_ANON));
+	}
+
+	/* Total size in gigabytes */
+	gb = (active + inactive) >> (30 - PAGE_SHIFT);
+	if (gb)
+		ratio = int_sqrt(10 * gb);
+	else
+		ratio = 1;
 
-	return inactive_anon_is_low_global(mz->zone);
+	return inactive * ratio < active;
 }
 #else
 static inline int inactive_anon_is_low(struct mem_cgroup_zone *mz)
@@ -1793,16 +1817,6 @@ static inline int inactive_anon_is_low(struct mem_cgroup_zone *mz)
 }
 #endif
 
-static int inactive_file_is_low_global(struct zone *zone)
-{
-	unsigned long active, inactive;
-
-	active = zone_page_state(zone, NR_ACTIVE_FILE);
-	inactive = zone_page_state(zone, NR_INACTIVE_FILE);
-
-	return (active > inactive);
-}
-
 /**
  * inactive_file_is_low - check if file pages need to be deactivated
  * @mz: memory cgroup and zone to check
@@ -1819,11 +1833,21 @@ static int inactive_file_is_low_global(struct zone *zone)
  */
 static int inactive_file_is_low(struct mem_cgroup_zone *mz)
 {
-	if (!mem_cgroup_disabled())
-		return mem_cgroup_inactive_file_is_low(mz->mem_cgroup,
-						       mz->zone);
+	unsigned long active, inactive;
+
+	if (mem_cgroup_disabled()) {
+		active = zone_page_state(mz->zone, NR_ACTIVE_FILE);
+		inactive = zone_page_state(mz->zone, NR_INACTIVE_FILE);
+	} else {
+		active = mem_cgroup_zone_nr_lru_pages(mz->mem_cgroup,
+				zone_to_nid(mz->zone), zone_idx(mz->zone),
+				BIT(LRU_ACTIVE_FILE));
+		inactive = mem_cgroup_zone_nr_lru_pages(mz->mem_cgroup,
+				zone_to_nid(mz->zone), zone_idx(mz->zone),
+				BIT(LRU_INACTIVE_FILE));
+	}
 
-	return inactive_file_is_low_global(mz->zone);
+	return inactive < active;
 }
 
 static int inactive_list_is_low(struct mem_cgroup_zone *mz, int file)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index f600557..2c813e1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1017,11 +1017,9 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 	}
 	seq_printf(m,
 		   "\n  all_unreclaimable: %u"
-		   "\n  start_pfn:         %lu"
-		   "\n  inactive_ratio:    %u",
+		   "\n  start_pfn:         %lu",
 		   zone->all_unreclaimable,
-		   zone->zone_start_pfn,
-		   zone->inactive_ratio);
+		   zone->zone_start_pfn);
 	seq_putc(m, '\n');
 }
 

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