[thisops uV2 06/10] vmstat: Use this_cpu_inc_return for vm statistics

[Christoph Lameter <cl@linux.com>]

[-- Attachment #1: this_cpu_add_vmstat --]
[-- Type: text/plain, Size: 1977 bytes --]

this_cpu_inc_return() saves us a memory access there. Code
size does not change.

V1->V2:
	- Fixed the location of the __per_cpu pointer attributes
	- Sparse checked

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/vmstat.c |   20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

Index: linux-2.6/mm/vmstat.c
===================================================================
--- linux-2.6.orig/mm/vmstat.c	2010-11-26 10:35:45.000000000 -0600
+++ linux-2.6/mm/vmstat.c	2010-11-26 10:45:49.000000000 -0600
@@ -167,8 +167,8 @@ static void refresh_zone_stat_thresholds
 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 				int delta)
 {
-	struct per_cpu_pageset * __percpu pcp = zone->pageset;
-	s8 * __percpu p = pcp->vm_stat_diff + item;
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
 	long x;
 	long t;
 
@@ -223,13 +223,11 @@ EXPORT_SYMBOL(mod_zone_page_state);
  */
 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 {
-	struct per_cpu_pageset * __percpu pcp = zone->pageset;
-	s8 * __percpu p = pcp->vm_stat_diff + item;
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
 	s8 v, t;
 
-	__this_cpu_inc(*p);
-
-	v = __this_cpu_read(*p);
+	v = __this_cpu_inc_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
 	if (unlikely(v > t)) {
 		s8 overstep = t >> 1;
@@ -247,13 +245,11 @@ EXPORT_SYMBOL(__inc_zone_page_state);
 
 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 {
-	struct per_cpu_pageset * __percpu pcp = zone->pageset;
-	s8 * __percpu p = pcp->vm_stat_diff + item;
+	struct per_cpu_pageset __percpu *pcp = zone->pageset;
+	s8 __percpu *p = pcp->vm_stat_diff + item;
 	s8 v, t;
 
-	__this_cpu_dec(*p);
-
-	v = __this_cpu_read(*p);
+	v = __this_cpu_dec_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
 	if (unlikely(v < - t)) {
 		s8 overstep = t >> 1;