Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755606AbZIJM6O (ORCPT ); Thu, 10 Sep 2009 08:58:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755311AbZIJM6O (ORCPT ); Thu, 10 Sep 2009 08:58:14 -0400 Received: from rcsinet12.oracle.com ([148.87.113.124]:53452 "EHLO rgminet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753224AbZIJM6N (ORCPT ); Thu, 10 Sep 2009 08:58:13 -0400 Date: Thu, 10 Sep 2009 08:57:42 -0400 From: Chris Mason To: Wu Fengguang Cc: Jan Kara , Andrew Morton , Jens Axboe , Dave Chinner , Peter Zijlstra , Christoph Hellwig , Artem Bityutskiy , LKML , "linux-fsdevel@vger.kernel.org" Subject: Re: [RFC][PATCH 7/7] writeback: balance_dirty_pages() shall write more than dirtied pages Message-ID: <20090910125742.GH5106@think> Mail-Followup-To: Chris Mason , Wu Fengguang , Jan Kara , Andrew Morton , Jens Axboe , Dave Chinner , Peter Zijlstra , Christoph Hellwig , Artem Bityutskiy , LKML , "linux-fsdevel@vger.kernel.org" References: <20090909145141.293229693@intel.com> <20090909150601.159061863@intel.com> <20090909154413.GC7949@duck.suse.cz> <20090910014201.GB10957@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090910014201.GB10957@localhost> User-Agent: Mutt/1.5.20 (2009-06-14) X-Source-IP: abhmt001.oracle.com [141.146.116.10] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090208.4AA8F7CA.00D1:SCFSTAT5015188,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1551 Lines: 30 On Thu, Sep 10, 2009 at 09:42:01AM +0800, Wu Fengguang wrote: > On Wed, Sep 09, 2009 at 11:44:13PM +0800, Jan Kara wrote: > > On Wed 09-09-09 22:51:48, Wu Fengguang wrote: > > > Some filesystem may choose to write much more than ratelimit_pages > > > before calling balance_dirty_pages_ratelimited_nr(). So it is safer to > > > determine number to write based on real number of dirtied pages. > > > > > > The increased write_chunk may make the dirtier more bumpy. This is > > > filesystem writers' duty not to dirty too much at a time without > > > checking the ratelimit. > > I don't get this. balance_dirty_pages_ratelimited_nr() is called when we > > dirty the page, not when we write it out. So a problem would only happen if > > filesystem dirties pages by set_page_dirty() and won't call > > balance_dirty_pages_ratelimited_nr(). But e.g. generic_perform_write() > > and do_wp_page() takes care of that. So where's the problem? > > It seems that btrfs_file_write() is writing in chunks of up to 1024-pages > (1024 is the computed nrptrs value in a 32bit kernel). And it calls > balance_dirty_pages_ratelimited_nr() each time it dirtied such a chunk. I can easily change this to call more often, but we do always call balance_dirty_pages to reflect how much ram we've really sent down. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/