[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, 15 insertions, 12 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7681d8ee04fe..be8235fb1939 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -645,16 +645,17 @@ static void shrink_cache(struct zone *zone, struct scan_control *sc)
                         goto done;
 
                 max_scan -= nr_scan;
-                if (current_is_kswapd())
-                        mod_page_state_zone(zone, pgscan_kswapd, nr_scan);
-                else
-                        mod_page_state_zone(zone, pgscan_direct, nr_scan);
                 nr_freed = shrink_list(&page_list, sc);
-                if (current_is_kswapd())
-                        mod_page_state(kswapd_steal, nr_freed);
-                mod_page_state_zone(zone, pgsteal, nr_freed);
 
-                spin_lock_irq(&zone->lru_lock);
+                local_irq_disable();
+                if (current_is_kswapd()) {
+                        __mod_page_state_zone(zone, pgscan_kswapd, nr_scan);
+                        __mod_page_state(kswapd_steal, nr_freed);
+                } else
+                        __mod_page_state_zone(zone, pgscan_direct, nr_scan);
+                __mod_page_state_zone(zone, pgsteal, nr_freed);
+
+                spin_lock(&zone->lru_lock);
                 /*
                  * Put back any unfreeable pages.
                  */
@@ -816,11 +817,13 @@ refill_inactive_zone(struct zone *zone, struct scan_control *sc)
                 }
         }
         zone->nr_active += pgmoved;
-        spin_unlock_irq(&zone->lru_lock);
-        pagevec_release(&pvec);
+        spin_unlock(&zone->lru_lock);
+
+        __mod_page_state_zone(zone, pgrefill, pgscanned);
+        __mod_page_state(pgdeactivate, pgdeactivate);
+        local_irq_enable();
 
-        mod_page_state_zone(zone, pgrefill, pgscanned);
-        mod_page_state(pgdeactivate, pgdeactivate);
+        pagevec_release(&pvec);
 }
 
 /*