linux-kernel - [PATCH v2 2/2] Filter unevictable page out in deactivate

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Date:	Tue,  3 May 2011 23:48:33 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Ying Han <yinghan@...gle.com>,
	Minchan Kim <minchan.kim@...il.com>
Subject: [PATCH v2 2/2] Filter unevictable page out in deactivate_page

It's pointless that deactive_page's pagevec operation about
unevictable page as it's nop.
This patch removes unnecessary overhead which might be a bit problem
in case that there are many unevictable page in system(ex, mprotect workload)

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@...il.com>
---
 mm/swap.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 2e9656d..e121ceb 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -511,6 +511,15 @@ static void drain_cpu_pagevecs(int cpu)
  */
 void deactivate_page(struct page *page)
 {
+
+	/*
+	 * In workload which system has many unevictable page(ex, 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);
 
-- 
1.7.1

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