From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 8 Mar 2002 11:06:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 8 Mar 2002 11:06:08 -0500 Received: from ns1.fast.net.uk ([212.42.162.2]:48913 "EHLO t2.fast.net.uk") by vger.kernel.org with ESMTP id ; Fri, 8 Mar 2002 11:06:04 -0500 Message-ID: <3C88E152.5070201@htec.demon.co.uk> Date: Fri, 08 Mar 2002 16:05:38 +0000 From: Christopher Quinn User-Agent: Mozilla/5.0 (compatible; MSIE5.5; Windows 98; X-Accept-Language: en-us MIME-Version: 1.0 To: Mark Hahn CC: linux-kernel@vger.kernel.org Subject: Re: Interprocess shared memory .... but file backed? In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mark Hahn wrote: >>>well MAP_PRIVATE is "dont share" so not with that 8) >>>Use MAP_SHARED and you'll get what you want >>> >>Certainly true! But MAP_SHARED gives uncontrolled flush of >>dirty data - so that's out for me. I only want 'privacy' to >>extend to the right to make changes permanent at my own >>discretion. >> > > right, and that's not what Unix provides. in particular, mmap > is a means for apps to be polite, not for them to strongarm > the kernel. in particular, if you mmap a file, much of the point > is that the kernel chooses how much of the state is in ram or > on disk. you can, of course, msync, or even munmap. > > > Seems a bit restrictive to me. After all Unix is not an ossified standard! :) Assuming clone() actually page table shares the vm covered by a mmap(MAP_PRIVATE) in the way I want, it isn't much to ask to be more *restrictive* on sharing? So far, it's looking as if my ideal is unattainable with the current kernel. Anyone disagree? -- rgrds, Chris Quinn