From: Magnus Damm <magnus.damm@gmail.com>

This patch reduces the amount of work done by __isolate_lru_page() and puts
it in isolate_lru_page() instead.  The patch reverts the
isolate_lru_pages() parameter and return value modification too.

Number of assembly lines occupied by isolate_lru_pages():

linux-2.6.14:          67
linux-2.6.14-mm2:      115
linux-2.6.14-mm2-slim: 71 (this patch)

Signed-off-by: Magnus Damm <magnus.damm@gmail.com>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 include/linux/mm_inline.h |   29 ++++++++++++-----------------
 mm/vmscan.c               |   43 ++++++++++++++++++++++++++++---------------
 2 files changed, 40 insertions(+), 32 deletions(-)

diff -puN include/linux/mm_inline.h~swap-migration-v5-lru-operations-inline-shrinkage include/linux/mm_inline.h
--- devel/include/linux/mm_inline.h~swap-migration-v5-lru-operations-inline-shrinkage	2005-11-22 22:30:26.000000000 -0800
+++ devel-akpm/include/linux/mm_inline.h	2005-11-22 22:30:26.000000000 -0800
@@ -44,24 +44,19 @@ del_page_from_lru(struct zone *zone, str
  *
  * - zone->lru_lock must be held
  */
-static inline int __isolate_lru_page(struct zone *zone, struct page *page)
+static inline int __isolate_lru_page(struct page *page)
 {
-	if (TestClearPageLRU(page)) {
-		if (get_page_testone(page)) {
-			/*
-			 * It is being freed elsewhere
-			 */
-			__put_page(page);
-			SetPageLRU(page);
-			return -ENOENT;
-		} else {
-			if (PageActive(page))
-				del_page_from_active_list(zone, page);
-			else
-				del_page_from_inactive_list(zone, page);
-			return 1;
-		}
+	if (unlikely(!TestClearPageLRU(page)))
+		return 0;
+
+	if (get_page_testone(page)) {
+		/*
+		 * It is being freed elsewhere
+		 */
+		__put_page(page);
+		SetPageLRU(page);
+		return -ENOENT;
 	}
 
-	return 0;
+	return 1;
 }
diff -puN mm/vmscan.c~swap-migration-v5-lru-operations-inline-shrinkage mm/vmscan.c
--- devel/mm/vmscan.c~swap-migration-v5-lru-operations-inline-shrinkage	2005-11-22 22:30:26.000000000 -0800
+++ devel-akpm/mm/vmscan.c	2005-11-22 22:30:26.000000000 -0800
@@ -584,27 +584,29 @@ keep:
  *
  * Appropriate locks must be held before calling this function.
  *
- * @zone:	The zone where lru_lock is held.
  * @nr_to_scan:	The number of pages to look through on the list.
  * @src:	The LRU list to pull pages off.
  * @dst:	The temp list to put pages on to.
+ * @scanned:	The number of pages that were scanned.
  *
- * returns the number of pages that were scanned.
+ * returns how many pages were moved onto *@dst.
  */
-static int isolate_lru_pages(struct zone *zone, int nr_to_scan,
-			     struct list_head *src, struct list_head *dst)
+static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
+			     struct list_head *dst, int *scanned)
 {
+	int nr_taken = 0;
 	struct page *page;
-	int scanned = 0;
+	int scan = 0;
 
-	while (scanned++ < nr_to_scan && !list_empty(src)) {
+	while (scan++ < nr_to_scan && !list_empty(src)) {
 		page = lru_to_page(src);
 		prefetchw_prev_lru_page(page, src, flags);
 
-		switch (__isolate_lru_page(zone, page)) {
+		switch (__isolate_lru_page(page)) {
 		case 1:
 			/* Succeeded to isolate page */
-			list_add(&page->lru, dst);
+			list_move(&page->lru, dst);
+			nr_taken++;
 			break;
 		case -ENOENT:
 			/* Not possible to isolate */
@@ -615,7 +617,8 @@ static int isolate_lru_pages(struct zone
 		}
 	}
 
-	return scanned;
+	*scanned = scan;
+	return nr_taken;
 }
 
 static void lru_add_drain_per_cpu(void *dummy)
@@ -640,7 +643,13 @@ int isolate_lru_page(struct page *page)
 
 redo:
 	spin_lock_irq(&zone->lru_lock);
-	rc = __isolate_lru_page(zone, page);
+	rc = __isolate_lru_page(page);
+	if (rc == 1) {
+		if (PageActive(page))
+			del_page_from_active_list(zone, page);
+		else
+			del_page_from_inactive_list(zone, page);
+	}
 	spin_unlock_irq(&zone->lru_lock);
 	if (rc == 0) {
 		/*
@@ -669,15 +678,18 @@ static void shrink_cache(struct zone *zo
 	spin_lock_irq(&zone->lru_lock);
 	while (max_scan > 0) {
 		struct page *page;
+		int nr_taken;
 		int nr_scan;
 		int nr_freed;
 
-		nr_scan = isolate_lru_pages(zone, sc->swap_cluster_max,
-					    &zone->inactive_list, &page_list);
+		nr_taken = isolate_lru_pages(sc->swap_cluster_max,
+					     &zone->inactive_list,
+					     &page_list, &nr_scan);
+		zone->nr_inactive -= nr_taken;
 		zone->pages_scanned += nr_scan;
 		spin_unlock_irq(&zone->lru_lock);
 
-		if (list_empty(&page_list))
+		if (nr_taken == 0)
 			goto done;
 
 		max_scan -= nr_scan;
@@ -786,9 +798,10 @@ refill_inactive_zone(struct zone *zone, 
 
 	lru_add_drain();
 	spin_lock_irq(&zone->lru_lock);
-	pgscanned = isolate_lru_pages(zone, nr_pages,
-				      &zone->active_list, &l_hold);
+	pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
+				    &l_hold, &pgscanned);
 	zone->pages_scanned += pgscanned;
+	zone->nr_active -= pgmoved;
 	spin_unlock_irq(&zone->lru_lock);
 
 	/*
_