From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 1 May 2002 17:39:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 1 May 2002 17:39:38 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:15120 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Wed, 1 May 2002 17:39:37 -0400 Message-ID: <3CD0605D.ACC42AA2@zip.com.au> Date: Wed, 01 May 2002 14:38:37 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-pre4 i686) X-Accept-Language: en MIME-Version: 1.0 To: Mike Fedyk CC: Guillaume Boissiere , linux-kernel@vger.kernel.org Subject: Re: [STATUS 2.5] May 1, 2002 In-Reply-To: <3CCFBB21.9046.7889B0D2@localhost> <20020501201927.GS574@matchmail.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mike Fedyk wrote: > > On Wed, May 01, 2002 at 09:53:37AM -0400, Guillaume Boissiere wrote: > > new framebuffer layer, as well as some more delayed disk block > > allocation bits. > > Actually Andrews work on address_space based writeback is related somewhat, > but really it's a rewrite/cleanup of the buffer layer. Delayed block > alocation is helped alot by this, and almost depends on it IIRC. > > One vote for a seperate listing in the status for "Address Space based > Writeback / Buffer layer cleanup". Well the next major step here is going direct pagecache<->BIO, bypassing the intermediate submit_bh for most I/O. Probably that will make most of the performance benefits of delayed-allocate go away. There are other reasons for implementing delalloc (XFS, improved layout, ...). So it ain't dead yet. At 48 bytes, 2.5's buffer_head is now precisely half the size of 2.4's. I'm hoping to be able to shed another eight bytes yet. With the pagecache<->BIO change, the buffer_head will most definitely become "per-page metadata which describes the state of sub-page segments" and not "something which is used for performing I/O". -