mm: filter unevictable page out in deactivate_page()

Minchan Kim · torvalds · commit 821ed6bbed3c · 2011-05-25T08:39:27.000-07:00
It's pointless that deactive_page's operates on unevictable pages.  This
patch removes unnecessary overhead which might be a bit problem in case
that there are many unevictable page in system(ex, mprotect workload)

[akpm@linux-foundation.org: tidy up comment]
Reviewed-by: KOSAKI Motohiro &lt;kosaki.motohiro@jp.fujitsu.com&gt;
Signed-off-by: Minchan Kim &lt;minchan.kim@gmail.com&gt;
Reviewed-by: Rik van Riel&lt;riel@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/mm/swap.c b/mm/swap.c
@@ -476,6 +476,13 @@ static void drain_cpu_pagevecs(int cpu)
  */
 void deactivate_page(struct page *page)
 {
+	/*
+	 * In a workload with many unevictable page such as mprotect, unevictable
+	 * page deactivation for accelerating reclaim is pointless.
+	 */
+	if (PageUnevictable(page))
+		return;
+
 	if (likely(get_page_unless_zero(page))) {
 		struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
 
