Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756157Ab0LJPq2 (ORCPT ); Fri, 10 Dec 2010 10:46:28 -0500 Received: from gir.skynet.ie ([193.1.99.77]:55794 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756080Ab0LJPq1 (ORCPT ); Fri, 10 Dec 2010 10:46:27 -0500 From: Mel Gorman To: Andrew Morton Cc: Simon Kirby , KOSAKI Motohiro , Shaohua Li , Dave Hansen , Johannes Weiner , linux-mm , linux-kernel , Mel Gorman Subject: [PATCH 3/6] mm: kswapd: Use the order that kswapd was reclaiming at for sleeping_prematurely() Date: Fri, 10 Dec 2010 15:46:22 +0000 Message-Id: <1291995985-5913-4-git-send-email-mel@csn.ul.ie> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1291995985-5913-1-git-send-email-mel@csn.ul.ie> References: <1291995985-5913-1-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: 3033 Lines: 79 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 order-0 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 Reviewed-by: Minchan Kim Reviewed-by: KAMEZAWA Hiroyuki --- mm/vmscan.c | 16 +++++++++++----- 1 files changed, 11 insertions(+), 5 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 6723101..4d968b0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2220,7 +2220,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, } /* 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; @@ -2230,7 +2230,7 @@ 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; @@ -2262,7 +2262,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) * For kswapd, balance_pgdat() will work across all this node's zones until * they are all at high_wmark_pages(zone). * - * Returns the number of pages which were actually freed. + * Returns the final order kswapd was reclaiming at * * There is special handling here for zones which are full of pinned pages. * This can happen if the pages are all mlocked, or if they are all used by @@ -2525,7 +2525,13 @@ 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; } static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) @@ -2652,7 +2658,7 @@ 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/