[ntp:questions] Loopstats updated less frequently than expected

Unruh unruh-spam at physics.ubc.ca
Sat May 23 16:15:13 UTC 2009


"David J Taylor" <david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid> writes:

>Folks,

>I have the following entries in ntpd.conf:

>server 192.168.0.2  iburst maxpoll 6
>server 192.168.0.7  maxpoll 6
>server 0.uk.pool.ntp.org minpoll 10

>.. and the following as the most recent loopstats:

>54974 37901.029 -0.000209922 13.840 0.000108471 0.007233 6
>54974 38229.033 0.000346890 13.846 0.000221473 0.007179 6
>54974 38754.041 -0.000217131 13.840 0.000287548 0.007132 6
>54974 38954.047 -0.000091306 13.839 0.000272631 0.006682 6

>I note that the times between these four entries are:

>328s
>525s
>200s

>As I have maxpoll set to 6, I would have expected entries no more than 64s 
>apart.  What am I failing to understand here?  The poll values reported in 
>ntpq -p are 64, 64 and 1024 - as expected.

You are forgetting that ntp throws away 7/8 of the stuff it collects.
(This is in an attempt to counter round trip biases).
Thus you would expect to have 8 times the max poll interval between
loopstats. (it is random so it is not always exactly 8 times sometimes
less, but never more, but it averages out to pretty close to 8 times.)


>Thanks,
>David 




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