[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, 32 insertions, 11 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 32d09c8d952b..dede8d412dca 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -144,22 +144,33 @@ struct page_state {
 extern void get_page_state(struct page_state *ret);
 extern void get_page_state_node(struct page_state *ret, int node);
 extern void get_full_page_state(struct page_state *ret);
-extern unsigned long __read_page_state(unsigned long offset);
-extern void __mod_page_state(unsigned long offset, unsigned long delta);
+extern unsigned long read_page_state_offset(unsigned long offset);
+extern void mod_page_state_offset(unsigned long offset, unsigned long delta);
+extern void __mod_page_state_offset(unsigned long offset, unsigned long delta);
 
 #define read_page_state(member) \
-        __read_page_state(offsetof(struct page_state, member))
+        read_page_state_offset(offsetof(struct page_state, member))
 
 #define mod_page_state(member, delta)   \
-        __mod_page_state(offsetof(struct page_state, member), (delta))
+        mod_page_state_offset(offsetof(struct page_state, member), (delta))
 
-#define inc_page_state(member)  mod_page_state(member, 1UL)
-#define dec_page_state(member)  mod_page_state(member, 0UL - 1)
-#define add_page_state(member,delta) mod_page_state(member, (delta))
-#define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))
+#define __mod_page_state(member, delta) \
+        __mod_page_state_offset(offsetof(struct page_state, member), (delta))
 
-#define mod_page_state_zone(zone, member, delta)                        \
- do {                                                                   \
+#define inc_page_state(member)          mod_page_state(member, 1UL)
+#define dec_page_state(member)          mod_page_state(member, 0UL - 1)
+#define add_page_state(member,delta)    mod_page_state(member, (delta))
+#define sub_page_state(member,delta)    mod_page_state(member, 0UL - (delta))
+
+#define __inc_page_state(member)        __mod_page_state(member, 1UL)
+#define __dec_page_state(member)        __mod_page_state(member, 0UL - 1)
+#define __add_page_state(member,delta)  __mod_page_state(member, (delta))
+#define __sub_page_state(member,delta)  __mod_page_state(member, 0UL - (delta))
+
+#define page_state(member) (*__page_state(offsetof(struct page_state, member)))
+
+#define state_zone_offset(zone, member)                                 \
+({                                                                      \
         unsigned offset;                                                \
         if (is_highmem(zone))                                           \
                 offset = offsetof(struct page_state, member##_high);    \
@@ -169,7 +180,17 @@ extern void __mod_page_state(unsigned long offset, unsigned long delta);
                 offset = offsetof(struct page_state, member##_dma32);   \
         else                                                            \
                 offset = offsetof(struct page_state, member##_dma);     \
-        __mod_page_state(offset, (delta));                              \
+        offset;                                                         \
+})
+
+#define __mod_page_state_zone(zone, member, delta)                      \
+ do {                                                                   \
+        __mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
+ } while (0)
+
+#define mod_page_state_zone(zone, member, delta)                        \
+ do {                                                                   \
+        mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
  } while (0)
 
 /*