In __zone_reclaim case, we don't want to shrink mapped page. Nonetheless,

we have isolated mapped page and re-add it into LRU's head.  It's
unnecessary CPU overhead and makes LRU churning.

Of course, when we isolate the page, the page might be mapped but when we
try to migrate the page, the page would be not mapped.  So it could be
migrated.  But race is rare and although it happens, it's no big deal.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index ad4b490b926c0bfac1239a2e2266a31f7ddaa0c4..19fd15d4734ce9156ae20277f7919f55bf8ceb08 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -170,6 +170,9 @@ static inline int is_unevictable_lru(enum lru_list l)
 #define ISOLATE_ACTIVE         ((__force fmode_t)0x2)
 /* Isolate clean file */
 #define ISOLATE_CLEAN          ((__force fmode_t)0x4)
+/* Isolate unmapped file */
+#define ISOLATE_UNMAPPED       ((__force fmode_t)0x8)
+
 /* LRU Isolation modes. */
 typedef unsigned __bitwise__ isolate_mode_t;
 

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 536b45ddc4c6596bab007969f8de454658c5b7e3..de74c8b78e36f4ad9b9c9815e5aaf387e70dc40e 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1049,6 +1049,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file)
        if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page)))
                return ret;
 
+       if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
+               return ret;
+
        if (likely(get_page_unless_zero(page))) {
                /*
                 * Be careful not to clear PageLRU until after we're
@@ -1478,6 +1481,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
                reclaim_mode |= ISOLATE_ACTIVE;
 
        lru_add_drain();
+
+       if (!sc->may_unmap)
+               reclaim_mode |= ISOLATE_UNMAPPED;
+       if (!sc->may_writepage)
+               reclaim_mode |= ISOLATE_CLEAN;
+
        spin_lock_irq(&zone->lru_lock);
 
        if (scanning_global_lru(sc)) {
@@ -1598,19 +1607,26 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
        struct page *page;
        struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
        unsigned long nr_rotated = 0;
+       isolate_mode_t reclaim_mode = ISOLATE_ACTIVE;
 
        lru_add_drain();
+
+       if (!sc->may_unmap)
+               reclaim_mode |= ISOLATE_UNMAPPED;
+       if (!sc->may_writepage)
+               reclaim_mode |= ISOLATE_CLEAN;
+
        spin_lock_irq(&zone->lru_lock);
        if (scanning_global_lru(sc)) {
                nr_taken = isolate_pages_global(nr_pages, &l_hold,
                                                &pgscanned, sc->order,
-                                               ISOLATE_ACTIVE, zone,
+                                               reclaim_mode, zone,
                                                1, file);
                zone->pages_scanned += pgscanned;
        } else {
                nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,
                                                &pgscanned, sc->order,
-                                               ISOLATE_ACTIVE, zone,
+                                               reclaim_mode, zone,
                                                sc->mem_cgroup, 1, file);
                /*
                 * mem_cgroup_isolate_pages() keeps track of