From owner-freebsd-alpha Tue Nov 12 8:21:58 2002 Delivered-To: freebsd-alpha@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2521637B401; Tue, 12 Nov 2002 08:21:57 -0800 (PST) Received: from pisello.ecn.uiowa.edu (pisello.ecn.uiowa.edu [128.255.23.215]) by mx1.FreeBSD.org (Postfix) with ESMTP id F2DBE43E75; Tue, 12 Nov 2002 08:21:55 -0800 (PST) (envelope-from mackey@engineering.uiowa.edu) Received: from engineering.uiowa.edu (localhost.localdomain [127.0.0.1]) by pisello.ecn.uiowa.edu (8.11.6/8.11.6) with ESMTP id gACGLsE01411; Tue, 12 Nov 2002 10:21:54 -0600 Message-ID: <3DD12AA2.8D84B3E2@engineering.uiowa.edu> Date: Tue, 12 Nov 2002 10:21:54 -0600 From: "Dr. Michael Mackey" Organization: University of Iowa X-Mailer: Mozilla 4.78 [en] (X11; U; Linux 2.4.19 i686) X-Accept-Language: en MIME-Version: 1.0 To: John Baldwin , freebsd-alpha@FreeBSD.org Subject: Re: Extreme time drift in SMP mode References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-alpha@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org You're right, the clock on the Lynx (2100a) is an 8254: (from the output of dmesg) FreeBSD 5.0-CURRENT #0: Mon Nov 11 15:31:50 CST 2002 mackey@home.:/usr/src/sys/alpha/compile/HOME Preloaded elf kernel "/boot/kernel/kernel" at 0xfffffc00006c2000. DEC AlphaServer 2100A AlphaServer 2100A 5/300, 291MHz 8192 byte page size, 2 processors. CPU: EV5 (21164) major=5 minor=5 OSF PAL rev: 0x4000100020116 real memory = 199155712 (189 MB) avail memory = 187490304 (178 MB) FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs --- snip --- Timecounters tick every 0.976 msec Timecounter "i8254" frequency 1193182 Hz --- snip --- John Baldwin wrote: > > On 11-Nov-2002 Andrew Gallatin wrote: > > > > Michael A. Mackey writes: > > > It takes precisely twice as long (20 seconds) to run `sleep 10`. > > > > > > Why can't ntpd keep things in line? > > > > > > > Because its not desgined to fix a clock which is that broken -- it > > only increments a second or so at a time. Far too slow for your > > purposes. > > So the clock is running at half-speed now? Hmm, the 2100[A] are > Tincup, not Turbolaser, right? So it should be using the i8254 for > its timecounter. Maybe the 8254 timecounter isn't setup right on > the 2100a? > > -- > > John Baldwin <>< http://www.FreeBSD.org/~jhb/ > "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ -- Prof. Michael A. Mackey (michael-mackey@uiowa.edu) Biomedical Engineering / Radiology University of Iowa, Iowa City, Iowa Voice: 319-335-6058 Fax: 319-335-5631 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message