Date: Thu, 15 May 2008 15:28:36 -0400 From: "Bob McConnell" <rvm@CBORD.com> To: <freebsd-questions@freebsd.org> Subject: RE: time drift Message-ID: <FF8482A96323694490C194BABEAC24A002B84250@Email.cbord.com> In-Reply-To: <20080515185758.GA12709@ikarus.thalreit> References: <20080515185758.GA12709@ikarus.thalreit>
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-----Original Message----- From: owner-freebsd-questions@freebsd.org [mailto:owner-freebsd-questions@freebsd.org] On Behalf Of Volker Jahns Sent: Thursday, May 15, 2008 2:58 PM To: freebsd-questions@freebsd.org Cc: volker@thalreit.de Subject: time drift 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 FreeBSD 7.0 on an otherwise almost identical system has a time drift of a few millisecs every half hour. 15 May 10:35:00 ntpdate[7999]: adjust time server 192.53.103.108 offset 0.009963 sec 15 May 10:35:51 ntpdate[8007]: adjust time server 192.53.103.108 offset -0.004890 sec 15 May 10:50:00 ntpdate[8042]: adjust time server 192.53.103.108 offset 0.010734 sec 15 May 11:05:00 ntpdate[8088]: adjust time server 192.53.103.108 offset 0.004523 sec 15 May 11:20:01 ntpdate[8114]: adjust time server 192.53.103.108 offset 0.005800 sec The 6.2 system is a production system, has a uptime of almost 300 days and I don't want=20 to experiment a lot with acpi, battery or so.=20 What would be your suspicion on the large time drift of the FreeBSD 6.2 system? --=20 Volker Jahns, volker@thalreit.de ---------------------------------- It loses 28 seconds per hour 28/3600 =3D 0.0077777777777777777, or less than 1 percent slow. That is well within normal parts tolerances for a new computer, and the drift usually gets worse as the hardware ages. I believe you are also looking at the software clock, not the hardware clock. The latter may be a little more accurate, since the former may be slowed down by interrupts and software that disables them. Install ntpd and let it adjust the clock for you. Bob McConnell
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