Date: Thu, 15 May 2008 22:19:42 +0100 From: Bruce Cran <bruce@cran.org.uk> To: Volker Jahns <volker@thalreit.de> Cc: freebsd-questions@freebsd.org Subject: Re: time drift Message-ID: <482CA8EE.7040906@cran.org.uk> In-Reply-To: <20080515203728.GA14284@ikarus.thalreit> References: <20080515185758.GA12709@ikarus.thalreit> <597571FB-C72D-4603-B379-A59A435843BE@mac.com> <20080515195302.GA13531@ikarus.thalreit> <20080515203728.GA14284@ikarus.thalreit>
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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
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