Changes mark_page_accessed to only set the PageAccessed bit, and
not move pages around the LRUs. This means we don't have to take
the lru_lock, and it also makes page ageing and scanning more consistient
and all handled in mm/vmscan.c


---

 linux-2.6-npiggin/include/linux/swap.h |    8 +++++--
 linux-2.6-npiggin/mm/filemap.c         |   16 ++------------
 linux-2.6-npiggin/mm/shmem.c           |    6 -----
 linux-2.6-npiggin/mm/swap.c            |   36 ---------------------------------
 linux-2.6-npiggin/mm/swapfile.c        |    6 ++---
 5 files changed, 13 insertions(+), 59 deletions(-)

diff -puN mm/filemap.c~vm-mark_page_accessed mm/filemap.c
--- linux-2.6/mm/filemap.c~vm-mark_page_accessed	2005-02-09 20:47:41.000000000 +1100
+++ linux-2.6-npiggin/mm/filemap.c	2005-02-09 21:02:53.000000000 +1100
@@ -438,10 +438,8 @@ EXPORT_SYMBOL(unlock_page);
  */
 void end_page_writeback(struct page *page)
 {
-	if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
-		if (!test_clear_page_writeback(page))
-			BUG();
-	}
+	if (!test_clear_page_writeback(page))
+		BUG();
 	smp_mb__after_clear_bit();
 	wake_up_page(page, PG_writeback);
 }
@@ -693,7 +691,6 @@ void do_generic_mapping_read(struct addr
 	unsigned long offset;
 	unsigned long req_size;
 	unsigned long next_index;
-	unsigned long prev_index;
 	loff_t isize;
 	struct page *cached_page;
 	int error;
@@ -702,7 +699,6 @@ void do_generic_mapping_read(struct addr
 	cached_page = NULL;
 	index = *ppos >> PAGE_CACHE_SHIFT;
 	next_index = index;
-	prev_index = ra.prev_page;
 	req_size = (desc->count + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 	offset = *ppos & ~PAGE_CACHE_MASK;
 
@@ -752,13 +748,7 @@ page_ok:
 		if (mapping_writably_mapped(mapping))
 			flush_dcache_page(page);
 
-		/*
-		 * When (part of) the same page is read multiple times
-		 * in succession, only mark it as accessed the first time.
-		 */
-		if (prev_index != index)
-			mark_page_accessed(page);
-		prev_index = index;
+		mark_page_accessed(page);
 
 		/*
 		 * Ok, we have the page, and it's up-to-date, so
diff -puN mm/swap.c~vm-mark_page_accessed mm/swap.c
--- linux-2.6/mm/swap.c~vm-mark_page_accessed	2005-02-09 20:47:41.000000000 +1100
+++ linux-2.6-npiggin/mm/swap.c	2005-02-11 20:56:44.000000000 +1100
@@ -96,42 +96,6 @@ int rotate_reclaimable_page(struct page 
 	return 0;
 }
 
-/*
- * FIXME: speed this up?
- */
-void fastcall activate_page(struct page *page)
-{
-	struct zone *zone = page_zone(page);
-
-	spin_lock_irq(&zone->lru_lock);
-	if (PageLRU(page) && !PageActive(page)) {
-		del_page_from_inactive_list(zone, page);
-		SetPageActive(page);
-		add_page_to_active_list(zone, page);
-		inc_page_state(pgactivate);
-	}
-	spin_unlock_irq(&zone->lru_lock);
-}
-
-/*
- * Mark a page as having seen activity.
- *
- * inactive,unreferenced	->	inactive,referenced
- * inactive,referenced		->	active,unreferenced
- * active,unreferenced		->	active,referenced
- */
-void fastcall mark_page_accessed(struct page *page)
-{
-	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
-		activate_page(page);
-		ClearPageReferenced(page);
-	} else if (!PageReferenced(page)) {
-		SetPageReferenced(page);
-	}
-}
-
-EXPORT_SYMBOL(mark_page_accessed);
-
 /**
  * lru_cache_add: add a page to the page lists
  * @page: the page to add
diff -puN include/linux/swap.h~vm-mark_page_accessed include/linux/swap.h
--- linux-2.6/include/linux/swap.h~vm-mark_page_accessed	2005-02-09 20:47:41.000000000 +1100
+++ linux-2.6-npiggin/include/linux/swap.h	2005-02-11 20:56:43.000000000 +1100
@@ -165,12 +165,16 @@ extern unsigned int nr_free_pagecache_pa
 /* linux/mm/swap.c */
 extern void FASTCALL(lru_cache_add(struct page *));
 extern void FASTCALL(lru_cache_add_active(struct page *));
-extern void FASTCALL(activate_page(struct page *));
-extern void FASTCALL(mark_page_accessed(struct page *));
 extern void lru_add_drain(void);
 extern int rotate_reclaimable_page(struct page *page);
 extern void swap_setup(void);
 
+/* Mark a page as having seen activity. */
+#define mark_page_accessed(page)	\
+do {					\
+	SetPageReferenced(page);	\
+} while (0)
+
 /* linux/mm/vmscan.c */
 extern int try_to_free_pages(struct zone **, unsigned int, unsigned int);
 extern int shrink_all_memory(int);
diff -puN include/linux/mm_inline.h~vm-mark_page_accessed include/linux/mm_inline.h
diff -puN mm/memory.c~vm-mark_page_accessed mm/memory.c
diff -puN mm/shmem.c~vm-mark_page_accessed mm/shmem.c
--- linux-2.6/mm/shmem.c~vm-mark_page_accessed	2005-02-09 20:47:42.000000000 +1100
+++ linux-2.6-npiggin/mm/shmem.c	2005-02-09 20:47:42.000000000 +1100
@@ -1523,11 +1523,7 @@ static void do_shmem_file_read(struct fi
 			 */
 			if (mapping_writably_mapped(mapping))
 				flush_dcache_page(page);
-			/*
-			 * Mark the page accessed if we read the beginning.
-			 */
-			if (!offset)
-				mark_page_accessed(page);
+			mark_page_accessed(page);
 		} else
 			page = ZERO_PAGE(0);
 
diff -puN include/linux/buffer_head.h~vm-mark_page_accessed include/linux/buffer_head.h
diff -puN mm/swapfile.c~vm-mark_page_accessed mm/swapfile.c
--- linux-2.6/mm/swapfile.c~vm-mark_page_accessed	2005-02-09 20:47:42.000000000 +1100
+++ linux-2.6-npiggin/mm/swapfile.c	2005-02-09 20:47:42.000000000 +1100
@@ -467,10 +467,10 @@ static unsigned long unuse_pmd(struct vm
 			pte_unmap(pte);
 
 			/*
-			 * Move the page to the active list so it is not
-			 * immediately swapped out again after swapon.
+			 * Touch the page so it is not immediately swapped
+			 * out again after swapon.
 			 */
-			activate_page(page);
+			mark_page_accessed(page);
 
 			/* add 1 since address may be 0 */
 			return 1 + address;

_