mm: page allocator: calculate a better estimate of NR_FREE_PAGES when memory is low...

[net-next-2.6.git] / include / linux / vmstat.h

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 7f43ccdc1d38c0eb919efe4891e1b91ec19c3705..eaaea37b3b75dd64b73a34a0e3beb31417bdd0d6 100644 (file)
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -170,6 +170,28 @@ static inline unsigned long zone_page_state(struct zone *zone,
        return x;
 }
 
+/*
+ * More accurate version that also considers the currently pending
+ * deltas. For that we need to loop over all cpus to find the current
+ * deltas. There is no synchronization so the result cannot be
+ * exactly accurate either.
+ */
+static inline unsigned long zone_page_state_snapshot(struct zone *zone,
+                                       enum zone_stat_item item)
+{
+       long x = atomic_long_read(&zone->vm_stat[item]);
+
+#ifdef CONFIG_SMP
+       int cpu;
+       for_each_online_cpu(cpu)
+               x += per_cpu_ptr(zone->pageset, cpu)->vm_stat_diff[item];
+
+       if (x < 0)
+               x = 0;
+#endif
+       return x;
+}
+
 extern unsigned long global_reclaimable_pages(void);
 extern unsigned long zone_reclaimable_pages(struct zone *zone);