Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754770Ab0LILSy (ORCPT ); Thu, 9 Dec 2010 06:18:54 -0500 Received: from gir.skynet.ie ([193.1.99.77]:47668 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753041Ab0LILSX (ORCPT ); Thu, 9 Dec 2010 06:18:23 -0500 From: Mel Gorman To: Simon Kirby Cc: KOSAKI Motohiro , Shaohua Li , Dave Hansen , Johannes Weiner , Andrew Morton , linux-mm , linux-kernel , Mel Gorman Subject: [PATCH 3/6] mm: kswapd: Use the order that kswapd was reclaiming at for sleeping_prematurely() Date: Thu, 9 Dec 2010 11:18:17 +0000 Message-Id: <1291893500-12342-4-git-send-email-mel@csn.ul.ie> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1291893500-12342-1-git-send-email-mel@csn.ul.ie> References: <1291893500-12342-1-git-send-email-mel@csn.ul.ie> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2365 Lines: 69 Before kswapd goes to sleep, it uses sleeping_prematurely() to check if there was a race pushing a zone below its watermark. If the race happened, it stays awake. However, balance_pgdat() can decide to reclaim at a lower order if it decides that high-order reclaim is not working as expected. This information is not passed back to sleeping_prematurely(). The impact is that kswapd remains awake reclaiming pages long after it should have gone to sleep. This patch passes the adjusted order to sleeping_prematurely and uses the same logic as balance_pgdat to decide if it's ok to go to sleep. Signed-off-by: Mel Gorman --- mm/vmscan.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index b4472a1..52e229e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2132,7 +2132,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced) } /* is kswapd sleeping prematurely? */ -static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) +static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) { int i; unsigned long balanced = 0; @@ -2142,7 +2142,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) if (remaining) return 1; - /* If after HZ/10, a zone is below the high mark, it's premature */ + /* Check the watermark levels */ for (i = 0; i < pgdat->nr_zones; i++) { struct zone *zone = pgdat->node_zones + i; @@ -2427,7 +2427,13 @@ out: } } - return sc.nr_reclaimed; + /* + * Return the order we were reclaiming at so sleeping_prematurely() + * makes a decision on the order we were last reclaiming at. However, + * if another caller entered the allocator slow path while kswapd + * was awake, order will remain at the higher level + */ + return order; } /* @@ -2537,7 +2543,7 @@ static int kswapd(void *p) */ if (!ret) { trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); - balance_pgdat(pgdat, order, classzone_idx); + order = balance_pgdat(pgdat, order, classzone_idx); } } return 0; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/