NTP Performance

[Gary E. Miller]

Yo Richard!

On Wed, 20 Nov 2019 16:02:32 -0600
Richard Laager via devel <devel at ntpsec.org> wrote:

> I now have a second stratum 1 server, with an independent setup. This
> allows me to compare the two.

Cool.

> Why does ntp1 have this very specific
> repeating pattern of local clock offset? It's roughly +7 us, -5 us, +2
> us, -4 us and then repeats again, over and over.

Check your crontab, and other recurrent jobs.  Those are way too large
for an idle server.  Could be a remote cronjob doing something like a 
log pull or other test.

> I could try fiddling around with the polling interval.

Nah, your jumps are too large for poll to have a noticeable effect on them.

> Another idea might be to switch to the PPS refclock on ntp2 to see if
> it behaves similarly with the ublox PPS.

My bet is that it does.

> As a second question, if you look at the ntp2 weekly graphs, there is
> a single huge transient. Any idea what that might be? I've seen these
> about once or twice a week since I put this in a couple weeks ago:
> https://ntp2.wiktel.com/week/

Usually some sort of kernel stall.  Likely some big job, or a backup,
happened during those events.  Less likely, but very possible, a disk
drive or NFS mount hung the entire system for 50 ms.

Also check the ntpd is locked to your PPS during the events.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin
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