[ntp:hackers] magnitudes for ntpq variables

gnu not unix gnu at wraith.sf.ca.us
Wed Mar 29 02:38:25 UTC 2006


Hi graphers-of-ntp-stats--

I'm converting to ntpq to gather stats for rrd plotting.

Compared to ntpdc, which uses nice scientific notation when
dumping "-c kern" values, there is some ambiguity (in my  mind
anyways) about the stats out of ntpq, for these:

offset, jitter, noise, stability

The frequency out of ntpq and ntpdc is understood to be ppm,
so no problem there.

If the values are taken as-is, the graphs look rather coarse
compared to using the ntpdc values (eg offset and jitter).

Looking at the "ntpq -p" columns for offset and jitter tend
to make me think that the similar "ntpq -c rv" variable names
should be scaled by 1000--since the "-p" stats are "millisecond
equals 1.0", not so?

The web man pages did not clarify this issue, that I could find.

Stability is mentioned on the web page for ntpq, but not noise.
Am I sent to the corner with RFC-1305 in my hands?

I'm wondering if I should also plot root delay and root dispersion.

The ntpq -p delay column is interesting, as it seems to show some
of the udp stack latency on my 100meg lan peers. I'm not sure what
the equivalent is in the ntpq "-c rv" output, though.

../Steven


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