[PATCH 04/34] mm: page-replace-use_once.patch

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

From: Peter Zijlstra <a.p.zijlstra@chello.nl>

Allow for a use-once hint.

API:

give a hint to the page replace algorithm:

	void page_replace_hint_use_once(struct page *);

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Marcelo Tosatti <marcelo.tosatti@cyclades.com>

---

 include/linux/mm_page_replace.h    |    1 +
 include/linux/mm_use_once_policy.h |    4 ++++
 mm/filemap.c                       |   13 ++++++++++++-
 3 files changed, 17 insertions(+), 1 deletion(-)

Index: linux-2.6-git/mm/filemap.c
===================================================================
--- linux-2.6-git.orig/mm/filemap.c
+++ linux-2.6-git/mm/filemap.c
@@ -403,7 +403,18 @@ int add_to_page_cache(struct page *page,
 		error = radix_tree_insert(&mapping->page_tree, offset, page);
 		if (!error) {
 			page_cache_get(page);
-			SetPageLocked(page);
+			/*
+			 * shmem_getpage()
+			 *   lookup_swap_cache()
+			 *   TestSetPageLocked()
+			 *   move_from_swap_cache()
+			 *     add_to_page_cache()
+			 *
+			 * That path calls us with a LRU page instead of a new
+			 * page. Don't set the hint for LRU pages.
+			 */
+			if (!TestSetPageLocked(page))
+				page_replace_hint_use_once(page);
 			page->mapping = mapping;
 			page->index = offset;
 			mapping->nrpages++;
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
@@ -8,6 +8,7 @@
 #include <linux/pagevec.h>
 
 /* void page_replace_hint_active(struct page *); */
+/* void page_replace_hint_use_once(struct page *); */
 extern void fastcall page_replace_add(struct page *);
 /* void page_replace_add_drain(void); */
 extern void __page_replace_add_drain(unsigned int);
Index: linux-2.6-git/include/linux/mm_use_once_policy.h
===================================================================
--- linux-2.6-git.orig/include/linux/mm_use_once_policy.h
+++ linux-2.6-git/include/linux/mm_use_once_policy.h
@@ -8,5 +8,9 @@ static inline void page_replace_hint_act
 	SetPageActive(page);
 }
 
+static inline void page_replace_hint_use_once(struct page *page)
+{
+}
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_USEONCE_POLICY_H */
-
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