Messages in this thread | | | Subject | Re: Clock inaccuracy seen on NVIDIA nForce2 systems | From | Jesse Stockall <> | Date | Thu, 14 Oct 2004 08:09:17 -0400 |
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On Wed, 2004-10-13 at 21:27, linux@horizon.com wrote: > > The system is running 2.6.9-rc4 and has been up for 2 days. I'm showing > > an offset of -32 seconds and growing. > > That's -185 ppm (parts per million) error, or -0.0185%. > > Typical cheap quartz crystals are +/- 100 ppm, but there are some cheaper > than that, and ceramic resonators like > http://www.ecsxtal.com/cerares.htm > > I know Dave Mills learned from experience that the original +/-100 ppm > specs in NTP weren't wide enough and he had to change it to cope with > +/-500 ppm error in some clocks. > > It *could* just be your motherboard's clock source.
possible but....
a) When I boot without 'acpi_skip_timer_override' and I fall back to using ExtINT for the timer there is no drift.
b) I rebooted and set FSB spread spectrum to 1.0 and let the machine run over night. In 10 hours of uptime I'm off -45 seconds and growing. This is -0.125%. So clearly having spread spectrum enabled does affect the clock.
Thanks
Jesse
-- Jesse Stockall <stockall@magma.ca>
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