From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753653Ab3EMIOg (ORCPT ); Mon, 13 May 2013 04:14:36 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53392 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752610Ab3EMIMt (ORCPT ); Mon, 13 May 2013 04:12:49 -0400 From: Mel Gorman To: Andrew Morton Cc: Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Michal Hocko , Kamezawa Hiroyuki , Linux-MM , LKML , Mel Gorman Subject: [PATCH 5/9] mm: vmscan: Do not allow kswapd to scan at maximum priority Date: Mon, 13 May 2013 09:12:36 +0100 Message-Id: <1368432760-21573-6-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1368432760-21573-1-git-send-email-mgorman@suse.de> References: <1368432760-21573-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Page reclaim at priority 0 will scan the entire LRU as priority 0 is considered to be a near OOM condition. Kswapd can reach priority 0 quite easily if it is encountering a large number of pages it cannot reclaim such as pages under writeback. When this happens, kswapd reclaims very aggressively even though there may be no real risk of allocation failure or OOM. This patch prevents kswapd reaching priority 0 and trying to reclaim the world. Direct reclaimers will still reach priority 0 in the event of an OOM situation. Signed-off-by: Mel Gorman Acked-by: Rik van Riel Acked-by: Johannes Weiner Reviewed-by: Michal Hocko --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index cd09803..1505c57 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2929,7 +2929,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, */ if (raise_priority || !sc.nr_reclaimed) sc.priority--; - } while (sc.priority >= 0 && + } while (sc.priority >= 1 && !pgdat_balanced(pgdat, order, *classzone_idx)); out: -- 1.8.1.4