[ntp:questions] Re: drift/offset

Folkert van Heusden folkert at vanheusden.com
Thu Feb 3 16:49:05 UTC 2005

> The graph at http://keetweej.vanheusden.com/ntp_graph.png
> appears to show points taken at intervals of  much less than your poll 
> interval of 64 seconds!

No, every 5 minuts a sample is taken. Latest sample on the right.

> How are you computing the offsets?   An offset 
> is presumably  t2 - t1;  what is the source of t2 and t1 for each point 
> on the graph?

echo `date +"%s"` `/usr/sbin/ntpdc -c loopinfo localhost | /bin/grep frequency | /bin/awk '{ print $2; }'` `/usr/sbin/ntpq -c pe | /bin/grep -e "^*" | /usr/bin/awk '{ print $9; }'` >> /var/log/ntp.stats.log

So it is the frequency-field of ntpdc -c loopinfo for the drift, and
for the offset I take the offset-field of the line with * at the first
position of ntpq -c pe:

     remote           refid      st t when poll reach   delay   offset  jitter
*GENERIC(0)      .DCFa.           0 l   38   64  377    0.000    0.349   3.695
^                                                                ^^^^^

Folkert van Heusden

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