From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p6MDVhBl086104 for ; Fri, 22 Jul 2011 08:31:43 -0500 Received: from mx2.suse.de (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 81E1DEF35C3 for ; Fri, 22 Jul 2011 06:31:42 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by cuda.sgi.com with ESMTP id FtatjeQAGoRy8Mhe for ; Fri, 22 Jul 2011 06:31:42 -0700 (PDT) Date: Fri, 22 Jul 2011 14:31:38 +0100 From: Mel Gorman Subject: Re: [PATCH 8/8] mm: vmscan: Do not writeback filesystem pages from kswapd Message-ID: <20110722133138.GY5349@suse.de> References: <1311265730-5324-1-git-send-email-mgorman@suse.de> <1311265730-5324-9-git-send-email-mgorman@suse.de> <1311339432.27400.36.camel@twins> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1311339432.27400.36.camel@twins> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Peter Zijlstra Cc: Rik van Riel , Jan Kara , LKML , XFS , Christoph Hellwig , Linux-MM , Minchan Kim , Wu Fengguang , Johannes Weiner On Fri, Jul 22, 2011 at 02:57:12PM +0200, Peter Zijlstra wrote: > On Thu, 2011-07-21 at 17:28 +0100, Mel Gorman wrote: > > Assuming that flusher threads will always write back dirty pages promptly > > then it is always faster for reclaimers to wait for flushers. This patch > > prevents kswapd writing back any filesystem pages. > > That is a somewhat sort changelog for such a big assumption ;-) > That is an understatement but the impact of the patch is discussed in detail in the leader. On NUMA, this patch has a negative impact so I put no effort into the changelog. The patch is part of the series because it was specifically asked for. > I think it can use a few extra words to explain the need to clean pages > from @zone vs writeback picks whatever fits best on disk and how that > works out wrt the assumption. > At the time of writing the changelog, I knew that flushers were not finding pages from the correct zones quickly enough in the NUMA usecase. The changelog documents the assumptions testing shows them to be false. > What requirements does this place on writeback and how does it meet > them. It places a requirement on writeback to prioritise pages from zones under memory pressure. It doesn't meet them. I mention in the leader that I think patch 8 should be dropped which is why the changelog sucks. -- Mel Gorman SUSE Labs _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs