From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 1/9] writeback: move dirty inodes from super_block to backing_dev_info Date: Fri, 28 Aug 2009 16:29:13 -0400 Message-ID: <20090828202913.GA18233@infradead.org> References: <1248989044-21605-1-git-send-email-jens.axboe@oracle.com> <1248989044-21605-2-git-send-email-jens.axboe@oracle.com> <20090806213505.GB20538@infradead.org> <20090812161250.GK12579@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, chris.mason@oracle.com, david@fromorbit.com, akpm@linux-foundation.org, jack@suse.cz, yanmin_zhang@linux.intel.com, richard@rsk.demon.co.uk, damien.wyart@free.fr, fweisbec@gmail.com, Alan.Brunelle@hp.com To: Jens Axboe Return-path: Content-Disposition: inline In-Reply-To: <20090812161250.GK12579@kernel.dk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Aug 12, 2009 at 06:12:50PM +0200, Jens Axboe wrote: > OK, so you'd prefer leaving the super block lists in place and rather > have the super blocks hanging off the bdi? That would solve the above problem. It would also implicitly provide increased locality by always writing batches of dirty inodes per fs. > What about file systems that > support more than one block device per mount, like btrfs? Or XFS :) > Can we assume > that they will forever provide a single bdi backing? btrfs currently has > this, just wondering about future implications. I don't see any point to assume things are forever. For making progress on this and getting it merged in .32 making that assumption is a good one IMHO. Now the question about that to do with a filesystem on multiple actual backing device is an interesting one. What about the case of having btrfs just one half of two disks each? Or same with a "normal" fs ontop of LVM/MD? Maybe in the end one thread(-pool) per filesystem and not just per backing dev is the way forward, with the threads schedule so that they don't interfer if they operate on the same backing dev? > > -- > Jens Axboe > ---end quoted text---