From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754589AbcDOJTf (ORCPT ); Fri, 15 Apr 2016 05:19:35 -0400 Received: from outbound-smtp04.blacknight.com ([81.17.249.35]:49658 "EHLO outbound-smtp04.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754534AbcDOJSB (ORCPT ); Fri, 15 Apr 2016 05:18:01 -0400 From: Mel Gorman To: Andrew Morton , Linux-MM Cc: Rik van Riel , Vlastimil Babka , Johannes Weiner , Jesper Dangaard Brouer , LKML , Mel Gorman Subject: [PATCH 25/27] mm: page_alloc: Cache the last node whose dirty limit is reached Date: Fri, 15 Apr 2016 10:13:31 +0100 Message-Id: <1460711613-2761-26-git-send-email-mgorman@techsingularity.net> X-Mailer: git-send-email 2.6.4 In-Reply-To: <1460711613-2761-1-git-send-email-mgorman@techsingularity.net> References: <1460711613-2761-1-git-send-email-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a page is about to be dirtied then the page allocator attempts to limit the total number of dirty pages that exists in any given zone. The call to node_dirty_ok is expensive so this patch records if the last pgdat examined hit the dirty limits. In some cases, this reduces the number of calls to node_dirty_ok(). Signed-off-by: Mel Gorman --- mm/page_alloc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 125f344ff105..d0ca26152716 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2889,6 +2889,8 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, { struct zoneref *z = ac->preferred_zoneref; struct zone *zone; + struct pglist_data *last_pgdat_dirty_limit = NULL; + /* * Scan zonelist, looking for a zone with enough free. * See also __cpuset_node_allowed() comment in kernel/cpuset.c. @@ -2921,8 +2923,15 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, * will require awareness of nodes in the * dirty-throttling and the flusher threads. */ - if (ac->spread_dirty_pages && !node_dirty_ok(zone->zone_pgdat)) - continue; + if (ac->spread_dirty_pages) { + if (last_pgdat_dirty_limit == zone->zone_pgdat) + continue; + + if (!node_dirty_ok(zone->zone_pgdat)) { + last_pgdat_dirty_limit = zone->zone_pgdat; + continue; + } + } mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK]; if (!zone_watermark_fast(zone, order, mark, -- 2.6.4