From owner-freebsd-questions@FreeBSD.ORG Thu May 15 21:20:14 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 132F01065674 for ; Thu, 15 May 2008 21:20:14 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from muon.bluestop.org (unknown [IPv6:2001:41c8:1:548a::2]) by mx1.freebsd.org (Postfix) with ESMTP id A93908FC13 for ; Thu, 15 May 2008 21:20:13 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from tau.draftnet (unknown [IPv6:2a01:348:10f:0:219:b9ff:fe54:f04a]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by muon.bluestop.org (Postfix) with ESMTP id 0D7CF30120; Thu, 15 May 2008 22:20:11 +0100 (BST) Message-ID: <482CA8EE.7040906@cran.org.uk> Date: Thu, 15 May 2008 22:19:42 +0100 From: Bruce Cran User-Agent: Thunderbird 2.0.0.14 (X11/20080505) MIME-Version: 1.0 To: Volker Jahns References: <20080515185758.GA12709@ikarus.thalreit> <597571FB-C72D-4603-B379-A59A435843BE@mac.com> <20080515195302.GA13531@ikarus.thalreit> <20080515203728.GA14284@ikarus.thalreit> In-Reply-To: <20080515203728.GA14284@ikarus.thalreit> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: time drift X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 May 2008 21:20:14 -0000 Volker Jahns wrote: > On Thu, May 15, 2008 at 09:53:02PM +0200, Volker Jahns wrote: >> On Thu, May 15, 2008 at 12:18:57PM -0700, Chuck Swiger wrote: >>> On May 15, 2008, at 11:57 AM, Volker Jahns wrote: >>>> FreeBSD 6.2 running on X86 hardware (FSC) shows a remarkable time >>>> drift >>>> >>>> running ntpdate every half hour shows that the system looses about >>>> 10-14 sec each time. >>>> 15 May 10:06:48 ntpdate[7200]: step time server 192.53.103.108 >>>> offset -13.799602 sec >>>> 15 May 10:36:48 ntpdate[7515]: step time server 192.53.103.108 >>>> offset -12.813941 sec >>>> 15 May 11:06:48 ntpdate[7879]: step time server 192.53.103.108 >>>> offset -13.651921 sec >>>> 15 May 11:36:50 ntpdate[8079]: step time server 192.53.103.108 >>>> offset -11.109298 sec >>>> 15 May 12:06:50 ntpdate[8289]: step time server 192.53.103.108 >>>> offset -11.836499 sec >>> You should also take a look at the output of "sysctl >>> kern.timecounter", and possibly switch to a different mechanism, if >>> the existing choice doesn't work out well for your machine... >> Thanks for the hint. > A few years ago a time drift problem had been observed by a German freebsd > user (http://www.freebsd.de/rachive/de-bsd-questions.200304/0643.html). > Time drift 15 sec every half hour, ntpd dies away running on his machine. > > Setting kern.timecounter.hardware to TSC had been recommended as a solution. There's also a FreeBSD PR open about this problem: http://www.freebsd.org/cgi/query-pr.cgi?pr=i386/123462 -- Bruce