Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755269Ab0K3RPs (ORCPT ); Tue, 30 Nov 2010 12:15:48 -0500 Received: from gir.skynet.ie ([193.1.99.77]:46851 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755069Ab0K3RPk (ORCPT ); Tue, 30 Nov 2010 12:15:40 -0500 From: Mel Gorman To: Simon Kirby Cc: KOSAKI Motohiro , Shaohua Li , Dave Hansen , linux-mm , linux-kernel , Mel Gorman Subject: [PATCH 2/3] mm: kswapd: Use the order that kswapd was reclaiming at for sleeping_prematurely() Date: Tue, 30 Nov 2010 17:15:38 +0000 Message-Id: <1291137339-6323-3-git-send-email-mel@csn.ul.ie> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1291137339-6323-1-git-send-email-mel@csn.ul.ie> References: <1291137339-6323-1-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: 2943 Lines: 94 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 | 30 ++++++++++++++++++++++++------ 1 files changed, 24 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 67e4283..9891efd 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2118,15 +2118,17 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, #endif /* 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; + bool all_zones_ok = true; + bool any_zone_ok = false; /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ 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; @@ -2138,10 +2140,20 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), 0, 0)) - return 1; + all_zones_ok = false; + else + any_zone_ok = true; } - return 0; + /* + * For high-order requests, any zone meeting the watermark is enough + * to allow kswapd go back to sleep + * For order-0, all zones must be balanced + */ + if (order) + return !any_zone_ok; + else + return !all_zones_ok; } /* @@ -2382,7 +2394,13 @@ out: zone_clear_flag(zone, ZONE_CONGESTED); } - 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; } /* @@ -2492,7 +2510,7 @@ static int kswapd(void *p) */ if (!ret) { trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); - balance_pgdat(pgdat, order, zone_highidx); + order = balance_pgdat(pgdat, order, zone_highidx); } } 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/