[PATCH 4/9] clockpro-use-once.patch

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

From: Rik van Riel <riel@surriel.com>

Simplify the use-once code.  I have not benchmarked this change yet,
but I expect it to have little impact on most workloads.  It gets rid
of some magic code though, which is nice.

Modified to work with this CLOCK-Pro implementation.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

 include/linux/mm_page_replace.h |   14 --------------
 mm/filemap.c                    |   11 ++---------
 mm/shmem.c                      |    6 +-----
 mm/swap.c                       |   27 +--------------------------
 mm/swapfile.c                   |    4 ++--
 mm/vmscan.c                     |   25 ++-----------------------
 6 files changed, 8 insertions(+), 79 deletions(-)

Index: linux-2.6-git/mm/filemap.c
===================================================================
--- linux-2.6-git.orig/mm/filemap.c
+++ linux-2.6-git/mm/filemap.c
@@ -387,6 +387,7 @@ int add_to_page_cache(struct page *page,
 		if (!error) {
 			page_cache_get(page);
 			SetPageLocked(page);
+			SetPageTest(page);
 			page->mapping = mapping;
 			page->index = offset;
 			mapping->nrpages++;
@@ -726,7 +727,6 @@ void do_generic_mapping_read(struct addr
 	unsigned long offset;
 	unsigned long last_index;
 	unsigned long next_index;
-	unsigned long prev_index;
 	loff_t isize;
 	struct page *cached_page;
 	int error;
@@ -735,7 +735,6 @@ void do_generic_mapping_read(struct addr
 	cached_page = NULL;
 	index = *ppos >> PAGE_CACHE_SHIFT;
 	next_index = index;
-	prev_index = ra.prev_page;
 	last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
 	offset = *ppos & ~PAGE_CACHE_MASK;
 
@@ -782,13 +781,7 @@ 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
Index: linux-2.6-git/mm/swap.c
===================================================================
--- linux-2.6-git.orig/mm/swap.c
+++ linux-2.6-git/mm/swap.c
@@ -90,37 +90,12 @@ int rotate_reclaimable_page(struct page 
 }
 
 /*
- * 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)) {
+	if (!PageReferenced(page))
 		SetPageReferenced(page);
-	}
 }
 
 EXPORT_SYMBOL(mark_page_accessed);
Index: linux-2.6-git/mm/swapfile.c
===================================================================
--- linux-2.6-git.orig/mm/swapfile.c
+++ linux-2.6-git/mm/swapfile.c
@@ -421,7 +421,7 @@ static void unuse_pte(struct vm_area_str
 	 * Move the page to the active list so it is not
 	 * immediately swapped out again after swapon.
 	 */
-	activate_page(page);
+	mark_page_accessed(page);
 }
 
 static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
@@ -523,7 +523,7 @@ static int unuse_mm(struct mm_struct *mm
 		 * Activate page so shrink_cache is unlikely to unmap its
 		 * ptes while lock is dropped, so swapoff can make progress.
 		 */
-		activate_page(page);
+		mark_page_accessed(page);
 		unlock_page(page);
 		down_read(&mm->mmap_sem);
 		lock_page(page);
Index: linux-2.6-git/mm/vmscan.c
===================================================================
--- linux-2.6-git.orig/mm/vmscan.c
+++ linux-2.6-git/mm/vmscan.c
@@ -219,27 +219,6 @@ static int shrink_slab(unsigned long sca
 	return ret;
 }
 
-/* Called without lock on whether page is mapped, so answer is unstable */
-static inline int page_mapping_inuse(struct page *page)
-{
-	struct address_space *mapping;
-
-	/* Page is in somebody's page tables. */
-	if (page_mapped(page))
-		return 1;
-
-	/* Be more reluctant to reclaim swapcache than pagecache */
-	if (PageSwapCache(page))
-		return 1;
-
-	mapping = page_mapping(page);
-	if (!mapping)
-		return 0;
-
-	/* File is mmap'd by somebody? */
-	return mapping_mapped(mapping);
-}
-
 static inline int is_page_cache_freeable(struct page *page)
 {
 	return page_count(page) - !!PagePrivate(page) == 2;
@@ -374,8 +353,8 @@ static try_pageout_t try_pageout(struct 
 		goto keep_locked;
 
 	referenced = page_referenced(page, 1);
-	/* In active use or really unfreeable?  Activate it. */
-	if (referenced && page_mapping_inuse(page))
+
+	if (referenced)
 		goto activate_locked;
 
 #ifdef CONFIG_SWAP
Index: linux-2.6-git/mm/shmem.c
===================================================================
--- linux-2.6-git.orig/mm/shmem.c
+++ linux-2.6-git/mm/shmem.c
@@ -1499,11 +1499,7 @@ 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);
 			page_cache_get(page);
Index: linux-2.6-git/include/linux/mm_page_replace.h
===================================================================
--- linux-2.6-git.orig/include/linux/mm_page_replace.h
+++ linux-2.6-git/include/linux/mm_page_replace.h
@@ -67,20 +67,6 @@ add_page_to_active_list(struct zone *zon
 }
 
 static inline void
-del_page_from_active_list(struct zone *zone, struct page *page)
-{
-	list_del(&page->lru);
-	zone->nr_active--;
-}
-
-static inline void
-del_page_from_inactive_list(struct zone *zone, struct page *page)
-{
-	list_del(&page->lru);
-	zone->nr_inactive--;
-}
-
-static inline void
 del_page_from_lru(struct zone *zone, struct page *page)
 {
 	list_del(&page->lru);
-
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