[PATCH] mm: page_state opt

Optimise page_state manipulations by introducing interrupt unsafe accessors
to page_state fields.  Callers must provide their own locking (either
disable interrupts or not update from interrupt context).

Switch over the hot callsites that can easily be moved under interrupts off
sections.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 4107f64ff749..6f3f7db27128 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -451,7 +451,11 @@ static void __page_set_anon_rmap(struct page *page,
 
         page->index = linear_page_index(vma, address);
 
-        inc_page_state(nr_mapped);
+        /*
+         * nr_mapped state can be updated without turning off
+         * interrupts because it is not modified via interrupt.
+         */
+        __inc_page_state(nr_mapped);
 }
 
 /**
@@ -498,7 +502,7 @@ void page_add_file_rmap(struct page *page)
         BUG_ON(!pfn_valid(page_to_pfn(page)));
 
         if (atomic_inc_and_test(&page->_mapcount))
-                inc_page_state(nr_mapped);
+                __inc_page_state(nr_mapped);
 }
 
 /**
@@ -522,7 +526,7 @@ void page_remove_rmap(struct page *page)
                  */
                 if (page_test_and_clear_dirty(page))
                         set_page_dirty(page);
-                dec_page_state(nr_mapped);
+                __dec_page_state(nr_mapped);
         }
 }