From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754570Ab0GZLdT (ORCPT ); Mon, 26 Jul 2010 07:33:19 -0400 Received: from mga14.intel.com ([143.182.124.37]:3325 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754547Ab0GZLdR (ORCPT ); Mon, 26 Jul 2010 07:33:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.55,261,1278313200"; d="scan'208";a="304338036" Date: Mon, 26 Jul 2010 19:32:45 +0800 From: Wu Fengguang To: Mel Gorman Cc: Andrew Morton , Dave Chinner , Jan Kara , Christoph Hellwig , Chris Mason , Jens Axboe , LKML , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH 2/6] writeback: the kupdate expire timestamp should be a moving target Message-ID: <20100726113245.GC6284@localhost> References: <20100722050928.653312535@intel.com> <20100722061822.630779474@intel.com> <20100726105200.GK5300@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100726105200.GK5300@csn.ul.ie> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 26, 2010 at 06:52:00PM +0800, Mel Gorman wrote: > On Thu, Jul 22, 2010 at 01:09:30PM +0800, Wu Fengguang wrote: > > Dynamicly compute the dirty expire timestamp at queue_io() time. > > Also remove writeback_control.older_than_this which is no longer used. > > > > writeback_control.older_than_this used to be determined at entrance to > > the kupdate writeback work. This _static_ timestamp may go stale if the > > kupdate work runs on and on. The flusher may then stuck with some old > > busy inodes, never considering newly expired inodes thereafter. > > > > This has two possible problems: > > > > - It is unfair for a large dirty inode to delay (for a long time) the > > writeback of small dirty inodes. > > > > - As time goes by, the large and busy dirty inode may contain only > > _freshly_ dirtied pages. Ignoring newly expired dirty inodes risks > > delaying the expired dirty pages to the end of LRU lists, triggering > > the very bad pageout(). Neverthless this patch merely addresses part > > of the problem. > > > > CC: Jan Kara > > Signed-off-by: Wu Fengguang > > Again, makes sense and I can't see a problem. There are some worth > smithing issues in the changelog such as Dynamicly -> Dynamically and Hah forgot to enable spell checking. > s/writeback_control.older_than_this used/writeback_control.older_than_this is used/ It's "used to", my god. > but other than that. > > Acked-by: Mel Gorman Thanks, Fengguang