linux-kernel - [PATCH 2/2] vmscan: activate executable pages after first usage

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Date:	Mon, 8 Aug 2011 15:07:00 +0400
From:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
To:	<linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>,
	<linux-kernel@...r.kernel.org>
CC:	Wu Fengguang <fengguang.wu@...el.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: [PATCH 2/2] vmscan: activate executable pages after first usage

Logic added in commit v2.6.30-5507-g8cab475
(vmscan: make mapped executable pages the first class citizen)
was noticeably weakened in commit v2.6.33-5448-g6457474
(vmscan: detect mapped file pages used only once)

Currently these pages can become "first class citizens" only after second usage.

After this patch page_check_references() will activate they after first usage,
and executable code gets yet better chance to stay in memory.

TODO:
run some cool tests like in v2.6.30-5507-g8cab475 =)

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
---
 mm/vmscan.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3cd766d..29b3612 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -727,6 +727,12 @@ static enum page_references page_check_references(struct page *page,
 		if (referenced_page || referenced_ptes > 1)
 			return PAGEREF_ACTIVATE;
 
+		/*
+		 * Activate file-backed executable pages after first usage.
+		 */
+		if (vm_flags & VM_EXEC)
+			return PAGEREF_ACTIVATE;
+
 		return PAGEREF_KEEP;
 	}
 

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