linux-kernel - [PATCH] vmscan: stop meaningless loop iteration when no reclaimable slab

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Message-Id: <20100709191308.FA25.A69D9226@jp.fujitsu.com>
Date:	Fri,  9 Jul 2010 19:13:58 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, Mel Gorman <mel@....ul.ie>,
	Rik van Riel <riel@...hat.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Johannes Weiner <hannes@...xchg.org>
Cc:	kosaki.motohiro@...fujitsu.com
Subject: [PATCH] vmscan: stop meaningless loop iteration when no reclaimable slab

If number of reclaimable slabs are zero, shrink_icache_memory() and
shrink_dcache_memory() return 0. but strangely shrink_slab() ignore
it and continue meaningless loop iteration.

This patch fixes it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
 mm/vmscan.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0f9f624..8f61adb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -243,6 +243,11 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
 			int nr_before;
 
 			nr_before = (*shrinker->shrink)(0, gfp_mask);
+			/* no slab objects, no more reclaim. */
+			if (nr_before == 0) {
+				total_scan = 0;
+				break;
+			}
 			shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
 			if (shrink_ret == -1)
 				break;
-- 
1.6.5.2



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