| Re: [chrony-dev] chronyc linear fit data point dump |
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On Fri, 11 Dec 2009, Miroslav Lichvar wrote:
On Fri, Dec 11, 2009 at 07:46:31AM +0100, Håkan Johansson wrote:
On Fri, 11 Dec 2009, Bill Unruh wrote:
On Fri, 11 Dec 2009, Håkan Johansson wrote:
I could not find a command in chronyc to dump all the currently active data
points used in the linear fit for a source. This list together with the
residuals would be nice to see what chronyd is up to. For monitoring, I'm
using (and quite happy with):
Not sure what you would want. Of course to some extent the offsets measured
and reported in measurement.log are used to determine that linear fit. But in
addition, those offsets are continually corrected for the changes in offset
and rate that chrony impliments, so the linear regression in on values which
can differ significantly from the measured offsets. What do you mean by "what
chrony is up to"? How would these values help you in any sense?
The idea would be to see this process of the raw data being
continuously adjusted in real-time. As sort of an educational tool.
A detailed report about selected source could be useful for remote
debugging. Maybe something similar to ntpq -c rv which includes a dump
of the NTP filter, transfered in plain text to allow modifications
without breaking the protocol.
Except ntp's process is really trivial. All ntp uses in its algorithm is the
current rate and the currently measured offset. chrony remembers up to 60
offsets for each source, all continually adjusted to compensate for current offset and rate
changes.
Of course that simply means that you have to dump more data. I have no
objection per se to anyone wanting this, except that it will almost never be
used, and it adds a small amount of complexity to the code, which can attract
bugs. Ie, I think it would be better if whoever wanted this coded it
themselves. It would not be hard, but feature creep is I think something to be
avoided.
(Of course we might discover that there is a bug in the current implimentation
which we would not have noticed without looking at the data.)
Certainly the dump should be in plain text.
--
William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273
Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324
UBC, Vancouver,BC | Program in Cosmology | unruh@xxxxxxxxxxxxxx
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