[ntp:questions] Re: Excessive polling

David L. Mills mills at udel.edu
Tue Nov 18 17:00:26 UTC 2003


NTPv3 (xntpd) operates as you describe; the poll intervals are clamped
to the reference clock. NTPv4 (ntpd) has no such restriction; the poll
intervals cheerfully escalate for sources other than the reference
clock. In the latter the clock discipline loop determines the minimum
poll interval independent of the particular source and this is usually
well above the minimum poll interval. However, some sources
intentionally oversample, like reference clocks. Other sources should
follow the loop, not the reference.


Tim Shoppa wrote:
> Terje Mathisen <terje.mathisen at hda.hydro.com> wrote in message news:<bp0q3p$log$1 at osl016lin.hda.hydro.com>...
> > Chris Hastie wrote:
> > > Amongst the changes:
> > > Added a simple MSF reference clock
> > >
> > > Could any of these things have caused my server to become greedy, or
> > > should I be looking for something else. BTW, I don't have any maxpoll
> > > statements in ntp.conf.
> >
> > Having a local refclock (MSF in your case) is enough to force all other
> > references to stay at minpoll.
> I've noticed this too.  Is this explicitly noted in the NTP documentation
> (or even commented in the sourcecode?)  I didn't find it, so I figured this
> was a undesired side-effect of having a local refclock.
> Tim.

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