From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bron Gondwana Subject: Re: BTRFS and old kernels. Date: Sun, 6 Apr 2008 11:31:45 +1000 Message-ID: <20080406013145.GA25252@brong.net> References: <20080406005712.GA24967@brong.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: btrfs-devel@oss.oracle.com, linux-btrfs@vger.kernel.org To: Bron Gondwana Return-path: In-Reply-To: <20080406005712.GA24967@brong.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: btrfs-devel-bounces@oss.oracle.com List-ID: On Sun, Apr 06, 2008 at 10:57:12AM +1000, Bron Gondwana wrote: > On Sat, Apr 05, 2008 at 08:13:47PM +0100, Miguel Sousa Filipe wrote: > > My question is, is there sill interestest in having btrfs compatible > > with older kernels (like, 2.6.20 or 2.6.18)? > > I'll post (or repost) patches that I need for btrfs-unstable to > > build/work on this ppc system of mine. > > It sort of depends who you ask. Personally, I see value in being > compatible with as wide range of kernels as possible in a development > filesystem that you want people to be testing. But then I'm not > doing any btrfs development, so I don't count for much. I guess I should justify this a bit.... ASSUME: I have a bunch of production Debian Etch machines running the latest Debian Etch production kernel (2.6.18-6-amd64 sounds like a convincing sort of version number) and I want to benchmark/test btrfs in my environment. CASE 1: I can upgrade the kernel on this system to 2.6.24+ and make sure all my hardware still works as expected, upgrade my udev/hal/whatever to be compatible. Possibly backport some userland tools that use new interfaces now... sounds like a whole pile of fun^H^H^Hwork. CASE 2: I can build a standalone btrfs module against my current kernel and test, having changed nothing but the filesystem. I know which one I would trust to give me a better idea of how stable/performant[1] btrfs is on my platform. (this all assuming that there aren't architectural changes in the intervening layers that make btrfs not work properly on the older kernels, but ext3/xfs/jfs/reiserfs/name-your-poison seem to have all remained stable right through those transitions[2].) Bron. [1] screw you http://boulter.com/blog/2004/08/19/performant-is-not-a-word/ and friends... [2] ok, there have been some exceptions to that, for example: http://oss.sgi.com/projects/xfs/faq.html#dir2