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system clock running 4% fast

Since I built my new amd64 host, my system clock is borked.  It runs about
4% fast-- gaining an hour a day.  This is way to much gain for ntpd to keep
up with.  To compensate I've had to set adjtimex --tick 9600, which
approximately corrects for the drift.

This would be tolerable, except that the drift rate isn't constant.  It's
all over the place.  Right after I boot it's stable at about -50 PPM, but
then after a few hours it suddenly goes nuts.  Look at the adjustments
ntpdate has to make when I run it once a minute:

20 Mar 05:05:58 ntpdate[17703]: step time server offset
0.060836 sec
20 Mar 05:06:55 ntpdate[17724]: step time server offset
-0.514396 sec
20 Mar 05:07:53 ntpdate[17734]: step time server offset
0.263715 sec
20 Mar 05:08:51 ntpdate[17740]: step time server offset
-0.047366 sec
20 Mar 05:09:48 ntpdate[17746]: step time server offset
-0.215751 sec
20 Mar 05:10:45 ntpdate[17755]: step time server offset
-0.646224 sec
20 Mar 05:11:42 ntpdate[17763]: step time server offset
-1.274522 sec

No wonder ntpd can't keep up.  The drift rate is all over the place.

I'm running a custom 64-bit kernel 2.6.15.  CPU is Athlon64 X2 4200+,
chipset is nForce4.

Many people are reporting problems related to time with the 2.6.15 kernel on
amd64, e.g.


A search for "amd64 linux clock" turns them up.  However, 80% or more of the
discussion seems to be about the "AMD/ATI bug", which applies to the
combination of AMD processors with some ATI chipsets (not sure which one). I
don't have an ATI chipset.  Still, I've tried all of the following boot
parameters that people have recommended for this problem:

disable_timer_pin_1 (my host won't boot)
noapic acpi=off
clock=pmtmr notsc

I also disabled CPU frequency spread spectrum in the BIOS.  The result is
always the same-- the clock is stable after I boot, but a few hours later it
goes nuts again.

Help!  How can I fix my system clock?  Do I a hardware problem?  How can I
tell?  Any help would be greatly appreciated.


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