per-zone LRU locking

PATCH In review Andrew Morton 1 participant 1 message Aug 11, 2002

Subsystems (8)

Memory management MM core Page allocator MGLRU +4 more subsystems

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Andrew Morton

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2002-08-11 07:33 UTC #0 lore raw

PATCH 18/21 per-zone LRU locking

Now the LRUs are per-zone, make their lock per-zone as well.

In this patch the per-zone lock shares a cacheline with the zone's buddy list lock, which is very bad. Some groundwork is needed to fix this well.

This change is expected to be a significant win on NUMA, where most page allocation comes from the local node's zones.

For NUMA the `struct zone' itself should really be placed in that node's memory, which is something the platform owners should look at. However the internode cache will help here.

Per-node kswapd would make heaps of sense too.

 include/linux/mm.h         |    2 
 include/linux/mmzone.h     |    1 
 include/linux/page-flags.h |    2 
 include/linux/swap.h       |    2 
 mm/filemap.c               |    3 -
 mm/memory.c                |    2 
 mm/page_alloc.c            |    3 -
 mm/rmap.c                  |    6 +-
 mm/swap.c                  |   99 +++++++++++++++++++++++++--------------------
 mm/vmscan.c                |   38 ++++++++---------
 10 files changed, 86 insertions(+), 72 deletions(-)

mm/filemap.c renamed from mm/filemap.c~per-zone-lock +1 -2

@@ -59,7 +59,7 @@
  *        ->swap_device_lock		(exclusive_swap_page, others)
  *	    ->rmap_lock			(to/from swapcache)
  *            ->mapping->page_lock
- *		->pagemap_lru_lock	(zap_pte_range)
+ *		->zone->lru_lock	(zap_pte_range)
  *      ->inode_lock			(__mark_inode_dirty)
  *        ->sb_lock			(fs/fs-writeback.c)
  *

@@ -68,7 +68,6 @@
  *    ->mapping->page_lock		(try_to_unmap_one)
  *
  */
-spinlock_t _pagemap_lru_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
 
 /*
  * Remove a page from the page cache and free it. Caller has to make

mm/memory.c renamed from mm/memory.c~per-zone-lock +1 -1

@@ -405,7 +405,7 @@ static void zap_pte_range(mmu_gather_t *
 			cached_rmap_lock(page, &rmap_lock, &last_lockno);
 			__page_remove_rmap(page, ptep);
 			/*
-			 * This will take pagemap_lru_lock.  Which nests inside
+			 * This will take zone->lru_lock.  Which nests inside
 			 * rmap_lock
 			 */
 			tlb_remove_page(tlb, &pvec, page);

mm/rmap.c renamed from mm/rmap.c~per-zone-lock +3 -3

@@ -14,7 +14,7 @@
 /*
  * Locking:
  * - the page->pte.chain is protected by the PG_chainlock bit,
- *   which nests within the pagemap_lru_lock, then the
+ *   which nests within the zone->lru_lock, then the
  *   mm->page_table_lock, and then the page lock.
  * - because swapout locking is opposite to the locking order
  *   in the page fault path, the swapout path uses trylocks

@@ -317,7 +317,7 @@ void page_remove_rmap(struct page *page,
  * table entry mapping a page. Because locking order here is opposite
  * to the locking order used by the page fault path, we use trylocks.
  * Locking:
- *	pagemap_lru_lock		page_launder()
+ *	zone->lru_lock			page_launder()
  *	    page lock			page_launder(), trylock
  *		rmap_lock		page_launder()
  *		    mm->page_table_lock	try_to_unmap_one(), trylock

@@ -385,7 +385,7 @@ out_unlock:
  * @page: the page to get unmapped
  *
  * Tries to remove all the page table entries which are mapping this
- * page, used in the pageout path.  Caller must hold pagemap_lru_lock
+ * page, used in the pageout path.  Caller must hold zone->lru_lock
  * and the page lock.  Return values are:
  *
  * SWAP_SUCCESS	- we succeeded in removing all mappings

mm/swap.c renamed from mm/swap.c~per-zone-lock +57 ~~-42~~

189 lines not on this page · raw message

mm/vmscan.c renamed from mm/vmscan.c~per-zone-lock +19 ~~-19~~

@@ -264,7 +264,7 @@ keep:
 }
 
 /*
- * pagemap_lru_lock is heavily contented.  We relieve it by quickly privatising
+ * zone->lru_lock is heavily contented.  We relieve it by quickly privatising
  * a batch of pages and working on them outside the lock.  Any pages which were
  * not freed will be added back to the LRU.
  *

@@ -292,7 +292,7 @@ shrink_cache(int nr_pages, struct zone *
 	pagevec_init(&pvec);
 
 	lru_add_drain();
-	spin_lock_irq(&_pagemap_lru_lock);
+	spin_lock_irq(&zone->lru_lock);
 	while (max_scan > 0 && nr_pages > 0) {
 		struct page *page;
 		int n = 0;

@@ -318,7 +318,7 @@ shrink_cache(int nr_pages, struct zone *
 			n++;
 		}
 		zone->nr_inactive -= n;
-		spin_unlock_irq(&_pagemap_lru_lock);
+		spin_unlock_irq(&zone->lru_lock);
 
 		if (list_empty(&page_list))
 			goto done;

@@ -331,7 +331,7 @@ shrink_cache(int nr_pages, struct zone *
 		if (nr_pages <= 0 && list_empty(&page_list))
 			goto done;
 
-		spin_lock_irq(&_pagemap_lru_lock);
+		spin_lock_irq(&zone->lru_lock);
 		/*
 		 * Put back any unfreeable pages.
 		 */

@@ -341,17 +341,17 @@ shrink_cache(int nr_pages, struct zone *
 				BUG();
 			list_del(&page->lru);
 			if (PageActive(page))
-				add_page_to_active_list(page);
+				add_page_to_active_list(zone, page);
 			else
-				add_page_to_inactive_list(page);
+				add_page_to_inactive_list(zone, page);
 			if (!pagevec_add(&pvec, page)) {
-				spin_unlock_irq(&_pagemap_lru_lock);
+				spin_unlock_irq(&zone->lru_lock);
 				__pagevec_release(&pvec);
-				spin_lock_irq(&_pagemap_lru_lock);
+				spin_lock_irq(&zone->lru_lock);
 			}
 		}
   	}
-	spin_unlock_irq(&_pagemap_lru_lock);
+	spin_unlock_irq(&zone->lru_lock);
 done:
 	pagevec_release(&pvec);
 	return nr_pages;

@@ -364,9 +364,9 @@ done:
  * processes, from rmap.
  *
  * If the pages are mostly unmapped, the processing is fast and it is
- * appropriate to hold pagemap_lru_lock across the whole operation.  But if
+ * appropriate to hold zone->lru_lock across the whole operation.  But if
  * the pages are mapped, the processing is slow (page_referenced()) so we
- * should drop pagemap_lru_lock around each page.  It's impossible to balance
+ * should drop zone->lru_lock around each page.  It's impossible to balance
  * this, so instead we remove the pages from the LRU while processing them.
  * It is safe to rely on PG_active against the non-LRU pages in here because
  * nobody will play with that bit on a non-LRU page.

@@ -388,7 +388,7 @@ refill_inactive_zone(struct zone *zone, 
 	unsigned last_lockno = -1;
 
 	lru_add_drain();
-	spin_lock_irq(&_pagemap_lru_lock);
+	spin_lock_irq(&zone->lru_lock);
 	while (nr_pages && !list_empty(&zone->active_list)) {
 		page = list_entry(zone->active_list.prev, struct page, lru);
 		prefetchw_prev_lru_page(page, &zone->active_list, flags);

@@ -398,7 +398,7 @@ refill_inactive_zone(struct zone *zone, 
 		list_move(&page->lru, &l_hold);
 		nr_pages--;
 	}
-	spin_unlock_irq(&_pagemap_lru_lock);
+	spin_unlock_irq(&zone->lru_lock);
 
 	while (!list_empty(&l_hold)) {
 		page = list_entry(l_hold.prev, struct page, lru);

@@ -416,7 +416,7 @@ refill_inactive_zone(struct zone *zone, 
 	drop_rmap_lock(&rmap_lock, &last_lockno);
 
 	pagevec_init(&pvec);
-	spin_lock_irq(&_pagemap_lru_lock);
+	spin_lock_irq(&zone->lru_lock);
 	while (!list_empty(&l_inactive)) {
 		page = list_entry(l_inactive.prev, struct page, lru);
 		prefetchw_prev_lru_page(page, &l_inactive, flags);

@@ -426,9 +426,9 @@ refill_inactive_zone(struct zone *zone, 
 			BUG();
 		list_move(&page->lru, &zone->inactive_list);
 		if (!pagevec_add(&pvec, page)) {
-			spin_unlock_irq(&_pagemap_lru_lock);
+			spin_unlock_irq(&zone->lru_lock);
 			__pagevec_release(&pvec);
-			spin_lock_irq(&_pagemap_lru_lock);
+			spin_lock_irq(&zone->lru_lock);
 		}
 	}
 	while (!list_empty(&l_active)) {

@@ -439,14 +439,14 @@ refill_inactive_zone(struct zone *zone, 
 		BUG_ON(!PageActive(page));
 		list_move(&page->lru, &zone->active_list);
 		if (!pagevec_add(&pvec, page)) {
-			spin_unlock_irq(&_pagemap_lru_lock);
+			spin_unlock_irq(&zone->lru_lock);
 			__pagevec_release(&pvec);
-			spin_lock_irq(&_pagemap_lru_lock);
+			spin_lock_irq(&zone->lru_lock);
 		}
 	}
 	zone->nr_active -= pgdeactivate;
 	zone->nr_inactive += pgdeactivate;
-	spin_unlock_irq(&_pagemap_lru_lock);
+	spin_unlock_irq(&zone->lru_lock);
 	pagevec_release(&pvec);
 
 	KERNEL_STAT_ADD(pgscan, nr_pages_in - nr_pages);

include/linux/mm.h renamed from include/linux/mm.h~per-zone-lock +1 -1

@@ -157,7 +157,7 @@ struct page {
 	struct address_space *mapping;	/* The inode (or ...) we belong to. */
 	unsigned long index;		/* Our offset within mapping. */
 	struct list_head lru;		/* Pageout list, eg. active_list;
-					   protected by pagemap_lru_lock !! */
+					   protected by zone->lru_lock !! */
 	union {
 		struct pte_chain * chain;	/* Reverse pte mapping pointer.
 					 * protected by PG_chainlock */

include/linux/page-flags.h renamed from include/linux/page-flags.h~per-zone-lock +1 -1

@@ -28,7 +28,7 @@
  *
  * Note that the referenced bit, the page->lru list_head and the active,
  * inactive_dirty and inactive_clean lists are protected by the
- * pagemap_lru_lock, and *NOT* by the usual PG_locked bit!
+ * zone->lru_lock, and *NOT* by the usual PG_locked bit!
  *
  * PG_error is set to indicate that an I/O error occurred on this page.
  *

include/linux/swap.h renamed from include/linux/swap.h~per-zone-lock +0 -2

@@ -212,8 +212,6 @@ extern struct swap_list_t swap_list;
 asmlinkage long sys_swapoff(const char *);
 asmlinkage long sys_swapon(const char *, int);
 
-extern spinlock_t _pagemap_lru_lock;
-
 extern void FASTCALL(mark_page_accessed(struct page *));
 
 extern spinlock_t swaplock;

mm/page_alloc.c renamed from mm/page_alloc.c~per-zone-lock +2 -1

@@ -829,7 +829,8 @@ void __init free_area_init_core(int nid,
 		printk("zone(%lu): %lu pages.\n", j, size);
 		zone->size = size;
 		zone->name = zone_names[j];
-		zone->lock = SPIN_LOCK_UNLOCKED;
+		spin_lock_init(&zone->lock);
+		spin_lock_init(&zone->lru_lock);
 		zone->zone_pgdat = pgdat;
 		zone->free_pages = 0;
 		zone->need_balance = 0;

include/linux/mmzone.h renamed from include/linux/mmzone.h~per-zone-lock +1 -0

@@ -44,6 +44,7 @@ struct zone {
 	unsigned long		pages_min, pages_low, pages_high;
 	int			need_balance;
 
+	spinlock_t		lru_lock;	
 	struct list_head	active_list;
 	struct list_head	inactive_list;
 	atomic_t		refill_counter;