From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965398AbXCUW1G (ORCPT ); Wed, 21 Mar 2007 18:27:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965381AbXCUW1G (ORCPT ); Wed, 21 Mar 2007 18:27:06 -0400 Received: from holomorphy.com ([66.93.40.71]:56489 "EHLO holomorphy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965398AbXCUW1E (ORCPT ); Wed, 21 Mar 2007 18:27:04 -0400 Date: Wed, 21 Mar 2007 15:26:59 -0700 From: William Lee Irwin III To: Valdis.Kletnieks@vt.edu Cc: Adam Litke , Andrew Morton , Arjan van de Ven , Christoph Hellwig , Ken Chen , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: pagetable_ops: Hugetlb character device example Message-ID: <20070321222659.GJ2986@holomorphy.com> References: <20070319200502.17168.17175.stgit@localhost.localdomain> <1174506228.21684.41.camel@localhost.localdomain> <200703211951.l2LJpVPS020364@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200703211951.l2LJpVPS020364@turing-police.cc.vt.edu> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 21 Mar 2007 14:43:48 CDT, Adam Litke said: >> The main reason I am advocating a set of pagetable_operations is to >> enable the development of a new hugetlb interface. On Wed, Mar 21, 2007 at 03:51:31PM -0400, Valdis.Kletnieks@vt.edu wrote: > Do you have an exit strategy for the *old* interface? Hello. My exit strategy was to make hugetlbfs an alias for ramfs when ramfs acquired the necessary functionality until expand-on-mmap() was merged. That would've allowed rm -rf fs/hugetlbfs/ outright. A compatibility wrapper for expand-on-mmap() around ramfs once ramfs acquires the necessary functionality is now the exit strategy. Given current opinions on general multiple pagesize support, by means of which the ramfs functionality is/was intended to be implemented, that time may well be "never." Character device analogues of /dev/zero are not replacements for the filesystem. Few or no transitions of existing users to such are possible. It primarily enables new users who really need anonymous hugetlb, such as numerical applications. The need for a filesystem namespace and persisting across process creation and destruction will not be eliminated by character devices. -- wli