From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932074Ab1GNPtV (ORCPT ); Thu, 14 Jul 2011 11:49:21 -0400 Received: from cantor2.suse.de ([195.135.220.15]:35618 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754639Ab1GNPtU (ORCPT ); Thu, 14 Jul 2011 11:49:20 -0400 Date: Thu, 14 Jul 2011 16:49:15 +0100 From: Mel Gorman To: Christoph Hellwig Cc: Linux-MM , LKML , XFS , Dave Chinner , Johannes Weiner , Wu Fengguang , Jan Kara , Rik van Riel , Minchan Kim Subject: Re: [PATCH 5/5] mm: writeback: Prioritise dirty inodes encountered by direct reclaim for background flushing Message-ID: <20110714154915.GV7529@suse.de> References: <1310567487-15367-1-git-send-email-mgorman@suse.de> <1310567487-15367-6-git-send-email-mgorman@suse.de> <20110714150959.GA30936@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20110714150959.GA30936@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 14, 2011 at 11:09:59AM -0400, Christoph Hellwig wrote: > On Wed, Jul 13, 2011 at 03:31:27PM +0100, Mel Gorman wrote: > > It is preferable that no dirty pages are dispatched from the page > > reclaim path. If reclaim is encountering dirty pages, it implies that > > either reclaim is getting ahead of writeback or use-once logic has > > prioritise pages for reclaiming that are young relative to when the > > inode was dirtied. > > what does this buy us? Very little. The vague intention was to avoid a situation where kswapds priority was raised such that it had to write pages to clean a particular zone. > If at all we should prioritize by a zone, > e.g. tell write_cache_pages only to bother with writing things out > if the dirty page is in a given zone. We'd probably still cluster > around it to make sure we get good I/O patterns, but would only start > I/O if it has a page we actually care about. > That would make more sense. I've dropped this patch entirely. -- Mel Gorman SUSE Labs