page-allocator: add inactive ratio calculation function of each zone

Factor the per-zone arithemetic inside setup_per_zone_inactive_ratio()'s
loop into a a separate function, calculate_zone_inactive_ratio().  This
function will be used in a later patch

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 12 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8629c84fd9ba..303607f1d323 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4478,22 +4478,26 @@ void setup_per_zone_wmarks(void)
  *    1TB     101        10GB
  *   10TB     320        32GB
  */
-static void __init setup_per_zone_inactive_ratio(void)
+void calculate_zone_inactive_ratio(struct zone *zone)
 {
-        struct zone *zone;
+        unsigned int gb, ratio;
 
-        for_each_zone(zone) {
-                unsigned int gb, ratio;
+        /* Zone size in gigabytes */
+        gb = zone->present_pages >> (30 - PAGE_SHIFT);
+        if (gb)
+                ratio = int_sqrt(10 * gb);
+        else
+                ratio = 1;
 
-                /* Zone size in gigabytes */
-                gb = zone->present_pages >> (30 - PAGE_SHIFT);
-                if (gb)
-                        ratio = int_sqrt(10 * gb);
-                else
-                        ratio = 1;
+        zone->inactive_ratio = ratio;
+}
 
-                zone->inactive_ratio = ratio;
-        }
+static void __init setup_per_zone_inactive_ratio(void)
+{
+        struct zone *zone;
+
+        for_each_zone(zone)
+                calculate_zone_inactive_ratio(zone);
 }
 
 /*