From: Steve Lord Subject: Re: Directories > 2GB Date: Mon, 09 Oct 2006 21:15:28 -0500 Message-ID: <452B0240.60203@xfs.org> References: <20061004165655.GD22010@schatzie.adilger.int> <452AC4BE.6090905@xfs.org> <20061010015512.GQ11034@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com Return-path: Received: from relay04.roc.ny.frontiernet.net ([66.133.182.167]:37058 "EHLO relay04.roc.ny.frontiernet.net") by vger.kernel.org with ESMTP id S1751316AbWJJCPg (ORCPT ); Mon, 9 Oct 2006 22:15:36 -0400 To: David Chinner In-Reply-To: <20061010015512.GQ11034@melbourne.sgi.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi Dave, My recollection is that it used to default to on, it was disabled because it needs to map the buffer into a single contiguous chunk of kernel memory. This was placing a lot of pressure on the memory remapping code, so we made it not default to on as reworking the code to deal with non contig memory was looking like a major effort. Steve David Chinner wrote: > On Mon, Oct 09, 2006 at 04:53:02PM -0500, Steve Lord wrote: >> You might want to think about keeping the directory a little >> more contiguous than individual disk blocks. XFS does have >> code in it to allocate the directory in chunks larger than >> a single file system block. It does not get used on linux >> because the code was written under the assumption you can >> see the whole chunk as a single piece of memory which does not >> work to well in the linux kernel. > > This code is enabled and seems to work in Linux. I don't know if it > passes xfsqa so I don't know how reliable this feature is. TO check > it all I did was run a quick test on a x86_64 kernel (4k page > size) using 16k directory blocks (4 pages): > > # mkfs.xfs -f -n size=16384 /dev/ubd/1 > ..... > # xfs_db -r -c "sb 0" -c "p dirblklog" /dev/ubd/1 > dirblklog = 2 > # mount /dev/ubd/1 /mnt/xfs > # for i in `seq 0 1 100000`; do touch fred.$i; done > # umount /mnt/xfs > # mount /mnt/xfs > # ls /mnt/xfs |wc -l > 100000 > # rm -rf /mnt/xfs/* > # ls /mnt/xfs |wc -l > 0 > # umount /mnt/xfs > # > > Cheers, > > Dave.