From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Chinner Subject: Re: [patch 10/21] buffer heads: Support slab defrag Date: Mon, 12 May 2008 10:24:03 +1000 Message-ID: <20080512002403.GP103491721@sgi.com> References: <20080510030831.796641881@sgi.com> <20080510030916.935905242@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Mel Gorman , andi@firstfloor.org, Rik van Riel , Pekka Enberg , mpm@selenic.com To: Christoph Lameter Return-path: Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:53101 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751560AbYELAYd (ORCPT ); Sun, 11 May 2008 20:24:33 -0400 Content-Disposition: inline In-Reply-To: <20080510030916.935905242@sgi.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, May 09, 2008 at 08:08:41PM -0700, Christoph Lameter wrote: > Defragmentation support for buffer heads. We convert the references to > buffers to struct page references and try to remove the buffers from > those pages. If the pages are dirty then trigger writeout so that the > buffer heads can be removed later. Oh, no, please don't trigger more random single page writeback from memory reclaim. We shoul dbe killing the VM's use of ->writepage, not encouraging it. If you are going to clean bufferheads (or pages), please clean entire mappings via ->writepages as it leads to far superior I/O patterns and a far higher aggregate rate of page cleaning..... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group