[PATCH] zone reclaim: do not check references to a page during zone reclaim

shrink_list() and refill_inactive() check all ptes pointing to a page for
reference bits in order to decide if the page should be put on the active
list.  This is not necessary for zone_reclaim since we are only interested
in removing unmapped pages.  Skip the checks in both functions.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5db32fdfaf392ae8a8ecea01aaef8589f55d161e..e1c64230ffdd908db888b41022ce1cf31e130ed9 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -443,6 +443,10 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc)
                BUG_ON(PageActive(page));
 
                sc->nr_scanned++;
+
+               if (!sc->may_swap && page_mapped(page))
+                       goto keep_locked;
+
                /* Double the slab pressure for mapped and swapcache pages */
                if (page_mapped(page) || PageSwapCache(page))
                        sc->nr_scanned++;
@@ -1231,7 +1235,7 @@ refill_inactive_zone(struct zone *zone, struct scan_control *sc)
         * Now use this metric to decide whether to start moving mapped memory
         * onto the inactive list.
         */
-       if (swap_tendency >= 100)
+       if (swap_tendency >= 100 && sc->may_swap)
                reclaim_mapped = 1;
 
        while (!list_empty(&l_hold)) {