[ntp:questions] no ntp synchronisation: 2s to 6s time shift !

Martin Burnicki martin.burnicki at meinberg.de
Fri Feb 15 10:58:14 UTC 2008


David Woolley wrote:
> Thierry MARTIN wrote:
>> I have been trying acpi_pm clocksource for a few days now and the
>> results are quite good :-).
>> The time drift is less than 1s per day (I would even say less that 500ms
>> but this has to be confirmed) which is much better than the default
>> config with tsc (>2s /day).
> It's almost certain that the same hardware time source is used for both,
> so discrepancies are likely to be attributable to software issues
> (although those may include problems in calibrating the frequency of
> various sources empirically, rather than by knowing how they derive from
> the common source).

If you mean the same base oscillator on the motherboard then this may be the

However, a bunch of clock signals with different clock rates are derived
from those oscillators, and the fact that different clocksource modules
yield different results make me assume that the problems are not with the
base oscillator but with the different types of counters and/or the
implementations of the modudules which use thos specific counters.

See also 

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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