| Re: [chrony-dev] PPSAPI: kernel consumer |
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On Tue, Feb 09, 2010 at 04:11:48PM +0300, Alexander Gordeev wrote:
> > BTW, I was thinking about the adjtimex problem with detecting when
> > were the values actually updated and it might be possible to find the
> > edge by setting adjtime to slew 1 us and then run readonly adjtime in
> > a loop every millisecond or so until it reports that there is no
> > offset left.
> >
> > This could make the measurements done while slewing much more
> > accurate. Not sure how reliable it would be, I'll run some tests.
>
> Sounds like a huge hack, sorry...
I doesn't seem to work reliably anyway. There is a strange overflow at
half second, sometimes the adjustment interval is one second,
sometimes only half.
However, I'm working now on calculating and processing the maximum
error when reading cooked time (as was probably originally intended by
Richard). Every sample has an error associated, which is included in
dispersion and in the weight used in linear regression. The samples
done while slewing will be less important in frequency/offset
calculation, or if the slew is longer, chrony will at least recover
faster.
Also, I think the refclock dispersion calculation may need to be
improved to react faster to temperature changes.
--
Miroslav Lichvar
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