From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 6DE536B004D for ; Mon, 8 Jun 2009 22:55:03 -0400 (EDT) Date: Tue, 9 Jun 2009 11:11:19 +0800 From: Wu Fengguang 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> Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: KOSAKI Motohiro , Rik van Riel , Christoph Lameter , "Zhang, Yanmin" , "linuxram@us.ibm.com" , linux-mm , LKML List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org