Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752904AbZFIDOH (ORCPT ); Mon, 8 Jun 2009 23:14:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755568AbZFIDNt (ORCPT ); Mon, 8 Jun 2009 23:13:49 -0400 Received: from mga03.intel.com ([143.182.124.21]:53223 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751972AbZFIDNn (ORCPT ); Mon, 8 Jun 2009 23:13:43 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.41,328,1241420400"; d="scan'208";a="152085972" Date: Tue, 9 Jun 2009 11:11:19 +0800 From: Wu Fengguang To: Mel Gorman Cc: KOSAKI Motohiro , Rik van Riel , Christoph Lameter , "Zhang, Yanmin" , "linuxram@us.ibm.com" , linux-mm , LKML Subject: Re: [PATCH 3/3] Do not unconditionally treat zones that fail zone_reclaim() as full Message-ID: <20090609031119.GB7875@localhost> References: <1244466090-10711-1-git-send-email-mel@csn.ul.ie> <1244466090-10711-4-git-send-email-mel@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1244466090-10711-4-git-send-email-mel@csn.ul.ie> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2030 Lines: 45 On Mon, Jun 08, 2009 at 09:01:30PM +0800, Mel Gorman wrote: > On NUMA machines, the administrator can configure zone_reclaim_mode that > is a more targetted form of direct reclaim. On machines with large NUMA > distances for example, a zone_reclaim_mode defaults to 1 meaning that clean > unmapped pages will be reclaimed if the zone watermarks are not being > met. The problem is that zone_reclaim() failing at all means the zone > gets marked full. > > This can cause situations where a zone is usable, but is being skipped > because it has been considered full. Take a situation where a large tmpfs > mount is occuping a large percentage of memory overall. The pages do not > get cleaned or reclaimed by zone_reclaim(), but the zone gets marked full > and the zonelist cache considers them not worth trying in the future. > > This patch makes zone_reclaim() return more fine-grained information about > what occured when zone_reclaim() failued. The zone only gets marked full if > it really is unreclaimable. If it's a case that the scan did not occur or > if enough pages were not reclaimed with the limited reclaim_mode, then the > zone is simply skipped. > > There is a side-effect to this patch. Currently, if zone_reclaim() > successfully reclaimed SWAP_CLUSTER_MAX, an allocation attempt would > go ahead. With this patch applied, zone watermarks are rechecked after > zone_reclaim() does some work. > > Signed-off-by: Mel Gorman Thanks for making the code a lot more readable :) Reviewed-by: Wu Fengguang > /* > * Do not scan if the allocation should not be delayed. > */ > if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) > - return 0; > + return ZONE_RECLAIM_NOSCAN; Why not kill the extra tab? -- 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/