Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 18 Dec 2000 07:18:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 18 Dec 2000 07:18:06 -0500 Received: from zeus.kernel.org ([209.10.41.242]:11013 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id ; Mon, 18 Dec 2000 07:17:53 -0500 Date: Mon, 18 Dec 2000 11:44:04 +0000 From: "Stephen C. Tweedie" To: Russell Cattelan Cc: "Stephen C. Tweedie" , Alexander Viro , Linus Torvalds , linux-kernel@vger.kernel.org Subject: Re: Test12 ll_rw_block error. Message-ID: <20001218114404.D21351@redhat.com> In-Reply-To:

<20001215105148.E11931@redhat.com> <3A3C11F2.130DE89E@thebarn.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: <3A3C11F2.130DE89E@thebarn.com>; from cattelan@thebarn.com on Sat, Dec 16, 2000 at 07:08:02PM -0600 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Sat, Dec 16, 2000 at 07:08:02PM -0600, Russell Cattelan wrote: > > There is a very clean way of doing this with address spaces. It's > > something I would like to see done properly for 2.5: eliminate all > > knowledge of buffer_heads from the VM layer. It would be pretty > > simple to remove page->buffers completely and replace it with a > > page->private pointer, owned by whatever address_space controlled the > > page. Instead of trying to unmap and flush buffers on the page > > directly, these operations would become address_space operations. > > Yes this is a lot of what page buf would like to do eventually. > Have the VM system pressure page_buf for pages which would > then be able to intelligently call the file system to free up cached pages. > A big part of getting Delay Alloc to not completely consume all the > system pages, is being told when it's time to start really allocating disk > space and push pages out. Delayed allocation is actually much easier, since it's entirely an operation on logical page addresses, not physical ones --- by definition you don't have any buffer_heads yet because you haven't decided on the disk blocks. If you're just dealing with pages, not blocks, then the address_space is the natural way of dealing with it already. Only the full semantics of the flush callback have been missing to date, and with 2.4.0-test12 even that is mostly solved, since page_launder will give you the writeback() callbacks you need to flush things to disk when you start getting memory pressure. You can even treat the writepage() as an advisory call. --Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/