From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965170AbXCLGYH (ORCPT ); Mon, 12 Mar 2007 02:24:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965163AbXCLGYH (ORCPT ); Mon, 12 Mar 2007 02:24:07 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:55772 "EHLO netops-testserver-4.corp.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965153AbXCLGYG (ORCPT ); Mon, 12 Mar 2007 02:24:06 -0400 Date: Mon, 12 Mar 2007 17:23:49 +1100 From: David Chinner To: Miklos Szeredi Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [patch 3/8] per backing_dev dirty and writeback page accounting Message-ID: <20070312062349.GN6095633@melbourne.sgi.com> References: <20070306180443.669036741@szeredi.hu> <20070306180550.793803735@szeredi.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070306180550.793803735@szeredi.hu> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 06, 2007 at 07:04:46PM +0100, Miklos Szeredi wrote: > From: Andrew Morton > > [tomoki.sekiyama.qu@hitachi.com: bugfix] > > Miklos Szeredi : > > Changes: > - updated to apply after clear_page_dirty_for_io() race fix > > This is needed for > > - balance_dirty_pages() deadlock fix > - fuse dirty page accounting > > I have no idea how serious the scalability problems with this are. If > they are serious, different solutions can probably be found for the > above, but this is certainly the simplest. Atomic operations to a single per-backing device from all CPUs at once? That's a pretty serious scalability issue and it will cause a major performance regression for XFS. I'd call this a showstopper right now - maybe you need to look at something like the ZVC code that Christoph Lameter wrote, perhaps? Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group