[RFC 1/8] Use ZVC for inactive and active counts

[Christoph Lameter <clameter@sgi.com>]

Use ZVC for nr_inactive and nr_active

The use of a ZVC for nr_inactive and nr_active allows a simplification
of some counter operations. More ZVC functionality is used for sums etc
in the following patches.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.20-rc6/include/linux/mm_inline.h
===================================================================
--- linux-2.6.20-rc6.orig/include/linux/mm_inline.h	2007-01-25 20:22:49.000000000 -0800
+++ linux-2.6.20-rc6/include/linux/mm_inline.h	2007-01-25 20:22:52.000000000 -0800
@@ -1,30 +1,29 @@
-
 static inline void
 add_page_to_active_list(struct zone *zone, struct page *page)
 {
 	list_add(&page->lru, &zone->active_list);
-	zone->nr_active++;
+	__inc_zone_state(zone, NR_ACTIVE);
 }
 
 static inline void
 add_page_to_inactive_list(struct zone *zone, struct page *page)
 {
 	list_add(&page->lru, &zone->inactive_list);
-	zone->nr_inactive++;
+	__inc_zone_state(zone, NR_INACTIVE);
 }
 
 static inline void
 del_page_from_active_list(struct zone *zone, struct page *page)
 {
 	list_del(&page->lru);
-	zone->nr_active--;
+	__dec_zone_state(zone, NR_ACTIVE);
 }
 
 static inline void
 del_page_from_inactive_list(struct zone *zone, struct page *page)
 {
 	list_del(&page->lru);
-	zone->nr_inactive--;
+	__dec_zone_state(zone, NR_INACTIVE);
 }
 
 static inline void
@@ -33,9 +32,9 @@ del_page_from_lru(struct zone *zone, str
 	list_del(&page->lru);
 	if (PageActive(page)) {
 		__ClearPageActive(page);
-		zone->nr_active--;
+		__dec_zone_state(zone, NR_ACTIVE);
 	} else {
-		zone->nr_inactive--;
+		__dec_zone_state(zone, NR_INACTIVE);
 	}
 }
 
Index: linux-2.6.20-rc6/include/linux/mmzone.h
===================================================================
--- linux-2.6.20-rc6.orig/include/linux/mmzone.h	2007-01-25 20:22:49.000000000 -0800
+++ linux-2.6.20-rc6/include/linux/mmzone.h	2007-01-25 20:22:52.000000000 -0800
@@ -47,6 +47,8 @@ struct zone_padding {
 #endif
 
 enum zone_stat_item {
+	NR_INACTIVE,
+	NR_ACTIVE,
 	NR_ANON_PAGES,	/* Mapped anonymous pages */
 	NR_FILE_MAPPED,	/* pagecache pages mapped into pagetables.
 			   only modified from process context */
@@ -197,8 +199,6 @@ struct zone {
 	struct list_head	inactive_list;
 	unsigned long		nr_scan_active;
 	unsigned long		nr_scan_inactive;
-	unsigned long		nr_active;
-	unsigned long		nr_inactive;
 	unsigned long		pages_scanned;	   /* since last reclaim */
 	int			all_unreclaimable; /* All pages pinned */
 
Index: linux-2.6.20-rc6/include/linux/vmstat.h
===================================================================
--- linux-2.6.20-rc6.orig/include/linux/vmstat.h	2007-01-25 20:22:49.000000000 -0800
+++ linux-2.6.20-rc6/include/linux/vmstat.h	2007-01-25 20:22:52.000000000 -0800
@@ -186,6 +186,9 @@ void inc_zone_page_state(struct page *, 
 void dec_zone_page_state(struct page *, enum zone_stat_item);
 
 extern void inc_zone_state(struct zone *, enum zone_stat_item);
+extern void __inc_zone_state(struct zone *, enum zone_stat_item);
+extern void dec_zone_state(struct zone *, enum zone_stat_item);
+extern void __dec_zone_state(struct zone *, enum zone_stat_item);
 
 void refresh_cpu_vm_stats(int);
 void refresh_vm_stats(void);
Index: linux-2.6.20-rc6/mm/vmscan.c
===================================================================
--- linux-2.6.20-rc6.orig/mm/vmscan.c	2007-01-25 20:22:49.000000000 -0800
+++ linux-2.6.20-rc6/mm/vmscan.c	2007-01-25 20:22:52.000000000 -0800
@@ -679,7 +679,7 @@ static unsigned long shrink_inactive_lis
 		nr_taken = isolate_lru_pages(sc->swap_cluster_max,
 					     &zone->inactive_list,
 					     &page_list, &nr_scan);
-		zone->nr_inactive -= nr_taken;
+		__mod_zone_page_state(zone, NR_INACTIVE, -nr_taken);
 		zone->pages_scanned += nr_scan;
 		spin_unlock_irq(&zone->lru_lock);
 
@@ -740,7 +740,8 @@ static inline void note_zone_scanning_pr
 
 static inline int zone_is_near_oom(struct zone *zone)
 {
-	return zone->pages_scanned >= (zone->nr_active + zone->nr_inactive)*3;
+	return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE)
+				+ zone_page_state(zone, NR_INACTIVE))*3;
 }
 
 /*
@@ -825,7 +826,7 @@ force_reclaim_mapped:
 	pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
 				    &l_hold, &pgscanned);
 	zone->pages_scanned += pgscanned;
-	zone->nr_active -= pgmoved;
+	__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
 
 	while (!list_empty(&l_hold)) {
@@ -857,7 +858,7 @@ force_reclaim_mapped:
 		list_move(&page->lru, &zone->inactive_list);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
-			zone->nr_inactive += pgmoved;
+			__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
 			spin_unlock_irq(&zone->lru_lock);
 			pgdeactivate += pgmoved;
 			pgmoved = 0;
@@ -867,7 +868,7 @@ force_reclaim_mapped:
 			spin_lock_irq(&zone->lru_lock);
 		}
 	}
-	zone->nr_inactive += pgmoved;
+	__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
 	pgdeactivate += pgmoved;
 	if (buffer_heads_over_limit) {
 		spin_unlock_irq(&zone->lru_lock);
@@ -885,14 +886,14 @@ force_reclaim_mapped:
 		list_move(&page->lru, &zone->active_list);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
-			zone->nr_active += pgmoved;
+			__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
 			pgmoved = 0;
 			spin_unlock_irq(&zone->lru_lock);
 			__pagevec_release(&pvec);
 			spin_lock_irq(&zone->lru_lock);
 		}
 	}
-	zone->nr_active += pgmoved;
+	__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
 
 	__count_zone_vm_events(PGREFILL, zone, pgscanned);
 	__count_vm_events(PGDEACTIVATE, pgdeactivate);
@@ -918,14 +919,16 @@ static unsigned long shrink_zone(int pri
 	 * Add one to `nr_to_scan' just to make sure that the kernel will
 	 * slowly sift through the active list.
 	 */
-	zone->nr_scan_active += (zone->nr_active >> priority) + 1;
+	zone->nr_scan_active +=
+		(zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
 	nr_active = zone->nr_scan_active;
 	if (nr_active >= sc->swap_cluster_max)
 		zone->nr_scan_active = 0;
 	else
 		nr_active = 0;
 
-	zone->nr_scan_inactive += (zone->nr_inactive >> priority) + 1;
+	zone->nr_scan_inactive +=
+		(zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
 	nr_inactive = zone->nr_scan_inactive;
 	if (nr_inactive >= sc->swap_cluster_max)
 		zone->nr_scan_inactive = 0;
@@ -1037,7 +1040,8 @@ unsigned long try_to_free_pages(struct z
 		if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
 			continue;
 
-		lru_pages += zone->nr_active + zone->nr_inactive;
+		lru_pages += zone_page_state(zone, NR_ACTIVE)
+				+ zone_page_state(zone, NR_INACTIVE);
 	}
 
 	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
@@ -1182,7 +1186,8 @@ loop_again:
 		for (i = 0; i <= end_zone; i++) {
 			struct zone *zone = pgdat->node_zones + i;
 
-			lru_pages += zone->nr_active + zone->nr_inactive;
+			lru_pages += zone_page_state(zone, NR_ACTIVE)
+					+ zone_page_state(zone, NR_INACTIVE);
 		}
 
 		/*
@@ -1219,8 +1224,9 @@ loop_again:
 			if (zone->all_unreclaimable)
 				continue;
 			if (nr_slab == 0 && zone->pages_scanned >=
-				    (zone->nr_active + zone->nr_inactive) * 6)
-				zone->all_unreclaimable = 1;
+				(zone_page_state(zone, NR_ACTIVE)
+				+ zone_page_state(zone, NR_INACTIVE)) * 6)
+					zone->all_unreclaimable = 1;
 			/*
 			 * If we've done a decent amount of scanning and
 			 * the reclaim ratio is low, start doing writepage
@@ -1385,18 +1391,22 @@ static unsigned long shrink_all_zones(un
 
 		/* For pass = 0 we don't shrink the active list */
 		if (pass > 0) {
-			zone->nr_scan_active += (zone->nr_active >> prio) + 1;
+			zone->nr_scan_active +=
+				(zone_page_state(zone, NR_ACTIVE) >> prio) + 1;
 			if (zone->nr_scan_active >= nr_pages || pass > 3) {
 				zone->nr_scan_active = 0;
-				nr_to_scan = min(nr_pages, zone->nr_active);
+				nr_to_scan = min(nr_pages,
+					zone_page_state(zone, NR_ACTIVE));
 				shrink_active_list(nr_to_scan, zone, sc, prio);
 			}
 		}
 
-		zone->nr_scan_inactive += (zone->nr_inactive >> prio) + 1;
+		zone->nr_scan_inactive +=
+			(zone_page_state(zone, NR_INACTIVE) >> prio) + 1;
 		if (zone->nr_scan_inactive >= nr_pages || pass > 3) {
 			zone->nr_scan_inactive = 0;
-			nr_to_scan = min(nr_pages, zone->nr_inactive);
+			nr_to_scan = min(nr_pages,
+				zone_page_state(zone, NR_INACTIVE));
 			ret += shrink_inactive_list(nr_to_scan, zone, sc);
 			if (ret >= nr_pages)
 				return ret;
@@ -1408,12 +1418,7 @@ static unsigned long shrink_all_zones(un
 
 static unsigned long count_lru_pages(void)
 {
-	struct zone *zone;
-	unsigned long ret = 0;
-
-	for_each_zone(zone)
-		ret += zone->nr_active + zone->nr_inactive;
-	return ret;
+	return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE);
 }
 
 /*
Index: linux-2.6.20-rc6/mm/vmstat.c
===================================================================
--- linux-2.6.20-rc6.orig/mm/vmstat.c	2007-01-25 20:22:49.000000000 -0800
+++ linux-2.6.20-rc6/mm/vmstat.c	2007-01-25 20:22:52.000000000 -0800
@@ -19,12 +19,10 @@ void __get_zone_counts(unsigned long *ac
 	struct zone *zones = pgdat->node_zones;
 	int i;
 
-	*active = 0;
-	*inactive = 0;
+	*active = node_page_state(pgdat->node_id, NR_ACTIVE);
+	*inactive = node_page_state(pgdat->node_id, NR_INACTIVE);
 	*free = 0;
 	for (i = 0; i < MAX_NR_ZONES; i++) {
-		*active += zones[i].nr_active;
-		*inactive += zones[i].nr_inactive;
 		*free += zones[i].free_pages;
 	}
 }
@@ -34,14 +32,12 @@ void get_zone_counts(unsigned long *acti
 {
 	struct pglist_data *pgdat;
 
-	*active = 0;
-	*inactive = 0;
+	*active = global_page_state(NR_ACTIVE);
+	*inactive = global_page_state(NR_INACTIVE);
 	*free = 0;
 	for_each_online_pgdat(pgdat) {
 		unsigned long l, m, n;
 		__get_zone_counts(&l, &m, &n, pgdat);
-		*active += l;
-		*inactive += m;
 		*free += n;
 	}
 }
@@ -239,7 +235,7 @@ EXPORT_SYMBOL(mod_zone_page_state);
  * in between and therefore the atomicity vs. interrupt cannot be exploited
  * in a useful way here.
  */
-static void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
+void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 {
 	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
 	s8 *p = pcp->vm_stat_diff + item;
@@ -260,9 +256,8 @@ void __inc_zone_page_state(struct page *
 }
 EXPORT_SYMBOL(__inc_zone_page_state);
 
-void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
+void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 {
-	struct zone *zone = page_zone(page);
 	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
 	s8 *p = pcp->vm_stat_diff + item;
 
@@ -275,6 +270,11 @@ void __dec_zone_page_state(struct page *
 		*p = overstep;
 	}
 }
+
+void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
+{
+	__dec_zone_state(page_zone(page), item);
+}
 EXPORT_SYMBOL(__dec_zone_page_state);
 
 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
@@ -454,6 +454,8 @@ const struct seq_operations fragmentatio
 
 static const char * const vmstat_text[] = {
 	/* Zoned VM counters */
+	"nr_active",
+	"nr_inactive",
 	"nr_anon_pages",
 	"nr_mapped",
 	"nr_file_pages",
@@ -529,8 +531,6 @@ static int zoneinfo_show(struct seq_file
 			   "\n        min      %lu"
 			   "\n        low      %lu"
 			   "\n        high     %lu"
-			   "\n        active   %lu"
-			   "\n        inactive %lu"
 			   "\n        scanned  %lu (a: %lu i: %lu)"
 			   "\n        spanned  %lu"
 			   "\n        present  %lu",
@@ -538,8 +538,6 @@ static int zoneinfo_show(struct seq_file
 			   zone->pages_min,
 			   zone->pages_low,
 			   zone->pages_high,
-			   zone->nr_active,
-			   zone->nr_inactive,
 			   zone->pages_scanned,
 			   zone->nr_scan_active, zone->nr_scan_inactive,
 			   zone->spanned_pages,
Index: linux-2.6.20-rc6/mm/page_alloc.c
===================================================================
--- linux-2.6.20-rc6.orig/mm/page_alloc.c	2007-01-25 20:22:49.000000000 -0800
+++ linux-2.6.20-rc6/mm/page_alloc.c	2007-01-25 20:22:52.000000000 -0800
@@ -1616,8 +1616,8 @@ void show_free_areas(void)
 			K(zone->pages_min),
 			K(zone->pages_low),
 			K(zone->pages_high),
-			K(zone->nr_active),
-			K(zone->nr_inactive),
+			K(zone_page_state(zone, NR_ACTIVE)),
+			K(zone_page_state(zone, NR_INACTIVE)),
 			K(zone->present_pages),
 			zone->pages_scanned,
 			(zone->all_unreclaimable ? "yes" : "no")
@@ -2684,8 +2684,6 @@ static void __meminit free_area_init_cor
 		INIT_LIST_HEAD(&zone->inactive_list);
 		zone->nr_scan_active = 0;
 		zone->nr_scan_inactive = 0;
-		zone->nr_active = 0;
-		zone->nr_inactive = 0;
 		zap_zone_vm_stats(zone);
 		atomic_set(&zone->reclaim_in_progress, 0);
 		if (!size)

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