page allocator: update NR_FREE_PAGES only as necessary

When pages are being freed to the buddy allocator, the zone NR_FREE_PAGES
counter must be updated.  In the case of bulk per-cpu page freeing, it's
updated once per page.  This retouches cache lines more than necessary.
Update the counters one per per-cpu bulk free.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index abe26003124d..d56e377ad085 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -456,7 +456,6 @@ static inline void __free_one_page(struct page *page,
                 int migratetype)
 {
         unsigned long page_idx;
-        int order_size = 1 << order;
 
         if (unlikely(PageCompound(page)))
                 if (unlikely(destroy_compound_page(page, order)))
@@ -466,10 +465,9 @@ static inline void __free_one_page(struct page *page,
 
         page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
 
-        VM_BUG_ON(page_idx & (order_size - 1));
+        VM_BUG_ON(page_idx & ((1 << order) - 1));
         VM_BUG_ON(bad_range(zone, page));
 
-        __mod_zone_page_state(zone, NR_FREE_PAGES, order_size);
         while (order < MAX_ORDER-1) {
                 unsigned long combined_idx;
                 struct page *buddy;
@@ -524,6 +522,8 @@ static void free_pages_bulk(struct zone *zone, int count,
         spin_lock(&zone->lock);
         zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
         zone->pages_scanned = 0;
+
+        __mod_zone_page_state(zone, NR_FREE_PAGES, count << order);
         while (count--) {
                 struct page *page;
 
@@ -542,6 +542,8 @@ static void free_one_page(struct zone *zone, struct page *page, int order,
         spin_lock(&zone->lock);
         zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
         zone->pages_scanned = 0;
+
+        __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
         __free_one_page(page, zone, order, migratetype);
         spin_unlock(&zone->lock);
 }
@@ -686,7 +688,6 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
                 list_del(&page->lru);
                 rmv_page_order(page);
                 area->nr_free--;
-                __mod_zone_page_state(zone, NR_FREE_PAGES, - (1UL << order));
                 expand(zone, page, order, current_order, area, migratetype);
                 return page;
         }
@@ -826,8 +827,6 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
                         /* Remove the page from the freelists */
                         list_del(&page->lru);
                         rmv_page_order(page);
-                        __mod_zone_page_state(zone, NR_FREE_PAGES,
-                                                        -(1UL << order));
 
                         if (current_order == pageblock_order)
                                 set_pageblock_migratetype(page,
@@ -900,6 +899,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
                 set_page_private(page, migratetype);
                 list = &page->lru;
         }
+        __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
         spin_unlock(&zone->lock);
         return i;
 }
@@ -1129,6 +1129,7 @@ again:
         } else {
                 spin_lock_irqsave(&zone->lock, flags);
                 page = __rmqueue(zone, order, migratetype);
+                __mod_zone_page_state(zone, NR_FREE_PAGES, -(1 << order));
                 spin_unlock(&zone->lock);
                 if (!page)
                         goto failed;