-----Original Message-----
[mailto:[EMAIL PROTECTED] On Behalf Of Volker Jahns
Sent: Thursday, May 15, 2008 2:58 PM
To: freebsd-questions@freebsd.org
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 offset
-13.799602 sec
15 May 10:36:48 ntpdate[7515]: step time server offset
-12.813941 sec
15 May 11:06:48 ntpdate[7879]: step time server offset
-13.651921 sec
15 May 11:36:50 ntpdate[8079]: step time server offset
-11.109298 sec
15 May 12:06:50 ntpdate[8289]: step time server 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 offset
0.009963 sec
15 May 10:35:51 ntpdate[8007]: adjust time server offset
-0.004890 sec
15 May 10:50:00 ntpdate[8042]: adjust time server offset
0.010734 sec
15 May 11:05:00 ntpdate[8088]: adjust time server offset
0.004523 sec
15 May 11:20:01 ntpdate[8114]: adjust time server offset
0.005800 sec

The 6.2 system is a production system, has a uptime of almost 300 days
and I don't want 
to experiment a lot with acpi, battery or so. 

What would be your suspicion on the large time drift of the FreeBSD 6.2


It loses 28 seconds per hour 28/3600 = 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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