From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263932AbTDNUP0 (for ); Mon, 14 Apr 2003 16:15:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263933AbTDNUP0 (for ); Mon, 14 Apr 2003 16:15:26 -0400 Received: from frankvm.xs4all.nl ([80.126.170.174]:29168 "EHLO iapetus.localdomain") by vger.kernel.org with ESMTP id S263932AbTDNUPY (for ); Mon, 14 Apr 2003 16:15:24 -0400 Date: Mon, 14 Apr 2003 22:27:41 +0200 From: Frank van Maarseveen To: "Richard B. Johnson" Cc: linux-kernel@vger.kernel.org Subject: Re: Memory mapped files question Message-ID: <20030414202741.GA26414@iapetus.localdomain> Mail-Followup-To: Frank van Maarseveen , "Richard B. Johnson" , linux-kernel@vger.kernel.org References: <004301c302bd$ed548680$fe64a8c0@webserver> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i X-Subliminal-Message: Use Linux! Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 14, 2003 at 04:13:52PM -0400, Richard B. Johnson wrote: > > Memory mapped files are supposed to be accessed through memory! > Any program that needs to know what's on the physical disk is > broken. If you need to write to files and know when they are > written to the physical media, you use a journaled file-system. It is not that simple. Shared mmaped files are _never_ flushed, at least in 2.4.x. So, without an explicit msync() a process (innd comes to mind) may loose years of updates upon a system crash or power outage. I have learned to live with it but I still find this a bit awkward. -- Frank