Re: [chrony-users] Fatal error : adjtimex() failed

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On Mon, Aug 20, 2012 at 10:49:21PM +0100, Tomalak Geret'kal wrote:
> On 20/08/2012 22:44, Bill Unruh wrote:
> >On Mon, 20 Aug 2012, Tomalak Geret'kal wrote:
> >>[sw200319 /root]# chronyc sources
> >>210 Number of sources = 2
> >>MS Name/IP atddress           Stratum Poll LastRx Last sample
> >>============================================================================
> >>
> >>#? PPS0                          0    4    43m  -1607ms[ +400ms]
> >>+/-  155ms
> >>#* GPS                           0    4     16    -14ms[  -14ms]
> >>+/-   60ms
> >
> >That indicates that the PPS is almost 2 seconds out from the gps.
> >a few 10s or
> >even 100s of ms I could understand, but this indicates that the
> >pps source is
> >getting the wrong seconds information.
> >
> >Also a fluctuation of 400ms or even 155 ms is pretty huge.
> But as you point out yourself, PPS is oblivious to time-of-day as it
> provides only *timing*. My understanding is that this value in
> "chronyc sources" is actually just an artefact of the PPS not having
> been used to discipline usage of the SHM source for a full 43
> minutes, so it's showing the result of jitter in the NMEA input?

It's the estimated offset and root distance at the current time based
on the 43 minutes old data, i.e. not very interesting.

Perhaps running chronyd in strace would tell us more why it fails.

> >Try putting in a "noselect" in that line, since you do not want
> >the system to
> >use the GPS time except to give the seconds to PPS.
> 
> *nods* Way ahead of you. :) I hadn't spotted that this would not
> prevent the PPS source (which is "lock"ed to the GPS source) from
> working. IMO this could use expanding in the user guide.

Patches for the documentation are very much appreciated :). There are
some other areas which needs update, for instance the section with
server name resolving on start is no longer valid, as chrony will try
it later after start.

-- 
Miroslav Lichvar

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