From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754345AbaEAIo5 (ORCPT ); Thu, 1 May 2014 04:44:57 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57698 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751917AbaEAIov (ORCPT ); Thu, 1 May 2014 04:44:51 -0400 From: Mel Gorman To: Linux-MM , Linux-FSDevel Cc: Johannes Weiner , Vlastimil Babka , Jan Kara , Michal Hocko , Hugh Dickins , Mel Gorman , Linux Kernel Subject: [PATCH 01/17] mm: page_alloc: Do not update zlc unless the zlc is active Date: Thu, 1 May 2014 09:44:32 +0100 Message-Id: <1398933888-4940-2-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1398933888-4940-1-git-send-email-mgorman@suse.de> References: <1398933888-4940-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The zlc is used on NUMA machines to quickly skip over zones that are full. However it is always updated, even for the first zone scanned when the zlc might not even be active. As it's a write to a bitmap that potentially bounces cache line it's deceptively expensive and most machines will not care. Only update the zlc if it was active. Signed-off-by: Mel Gorman --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 5dba293..f8b80c3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2044,7 +2044,7 @@ try_this_zone: if (page) break; this_zone_full: - if (IS_ENABLED(CONFIG_NUMA)) + if (IS_ENABLED(CONFIG_NUMA) && zlc_active) zlc_mark_zone_full(zonelist, z); } -- 1.8.4.5