From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p6QBL1sc125545 for ; Tue, 26 Jul 2011 06:21:02 -0500 Received: from ipmail05.adl6.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 6E5D81D8E871 for ; Tue, 26 Jul 2011 04:20:59 -0700 (PDT) Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by cuda.sgi.com with ESMTP id 9j5tILqFFRNRKCy0 for ; Tue, 26 Jul 2011 04:20:59 -0700 (PDT) Date: Tue, 26 Jul 2011 21:20:55 +1000 From: Dave Chinner Subject: Re: [RFC PATCH 0/8] Reduce filesystem writeback from page reclaim v2 Message-ID: <20110726112055.GC8048@dastard> References: <1311265730-5324-1-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1311265730-5324-1-git-send-email-mgorman@suse.de> 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: Mel Gorman Cc: Rik van Riel , Jan Kara , LKML , XFS , Christoph Hellwig , Linux-MM , Minchan Kim , Wu Fengguang , Johannes Weiner On Thu, Jul 21, 2011 at 05:28:42PM +0100, Mel Gorman wrote: > Warning: Long post with lots of figures. If you normally drink coffee > and you don't have a cup, get one or you may end up with a case of > keyboard face. [snip] > Overall, having kswapd avoiding writes does improve performance > which is not a surprise. Dave asked "do we even need IO at all from > reclaim?". On NUMA machines, the answer is "yes" unless the VM can > wake the flusher thread to clean a specific node. Great answer, Mel. ;) > When kswapd never > writes, processes can stall for significant periods of time waiting on > flushers to clean the correct pages. If all writing is to be deferred > to flushers, it must ensure that many writes on one node would not > starve requests for cleaning pages on another node. Ok, so that's a direction we need to work towards, then. > I'm currently of the opinion that we should consider merging patches > 1-7 and discuss what is required before merging. It can be tackled > later how the flushers can prioritise writing of pages belonging to > a particular zone before disabling all writes from reclaim. Sounds reasonable to me. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs