From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 10 Nov 2002 15:10:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 10 Nov 2002 15:10:33 -0500 Received: from gate.in-addr.de ([212.8.193.158]:28691 "HELO mx.in-addr.de") by vger.kernel.org with SMTP id ; Sun, 10 Nov 2002 15:10:32 -0500 Date: Sun, 10 Nov 2002 21:16:46 +0100 From: Lars Marowsky-Bree To: linux-kernel@vger.kernel.org Subject: Re: Voyager subarchitecture for 2.5.46 Message-ID: <20021110201645.GI835@marowsky-bree.de> References: <20021110191822.GA1237@elf.ucw.cz> <20021110194204.GF3068@atrey.karlin.mff.cuni.cz> <6usmy99osn.fsf@zork.zork.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6usmy99osn.fsf@zork.zork.net> User-Agent: Mutt/1.4i X-Ctuhulu: HASTUR Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 2002-11-10T20:02:00, Sean Neakums said: > > I believe you need it system-global. If task A tells task B "its > > 10:30:00" and than task B does gettimeofday and gets "10:29:59", it > > will be confused for sure. > Hence the requirement that it be monotonically increasing. Processes expecting time to increase strictly monotonically across process boundaries will enjoy life in cluster settings or when the admin adjusts the time. In short, those programs are already broken. Of course, physically that should be true, Star Trek or not ;), but it is a really hard promise to keep across multiple nodes (think Mosix, CC/NC-NUMA or even real clusters which distributed processing). Serializing all gettimeofday() calls via a single counter at least is a rather bad idea. Sincerely, Lars Marowsky-Brée -- Principal Squirrel SuSE Labs - Research & Development, SuSE Linux AG "If anything can go wrong, it will." "Chance favors the prepared (mind)." -- Capt. Edward A. Murphy -- Louis Pasteur