-g screqup (from IRC)

Gary E. Miller gem at rellim.com
Mon Sep 12 21:38:07 UTC 2016

Yo Hal!

On Mon, 12 Sep 2016 14:15:05 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> [to get clock-step logging]
> > Can you tell me which logging?  Then I can test for this case.  
> It's part of:
>   logconfig =syncall +clockall +peerall +sysall
> I think it's in sysall, but I'm not sure.

sysall not in the ntp.conf man page.  I also do not see anything related
to allow_panic that would log when the options is taken: ntp_loopfilter.c

> >> The -g switch is supposed to be very simple.  It allows a large
> >> initial step. Other than that, it shouldn't do anything.  
> > Sadly, simple things have bad consequences.  See all my previous
> > posts about nntpd bad startup behavior.   
> I'm not saying that there aren't problems, but blaming them on -g
> doesn't make sense.
> If -g really is causing troubles, then we need a test case.

I got the test case, as in my previous email:

# killall ntpd; sleep 1; ntpd -N -g

But so many bad things going on there hard to tell one from the other.

Looking at my charts you can always tells when I do that, it stands out
quite tall.

And data to go with my test cases:


I'm trying to get better in the notes, so everyone can see what is
going on.

Feel free to run your own test cases and port the data.

But you are right, I see no way in the code the -g is causing that, so I
am getting maybe a false correlation.  But clar from above that very
bad things do happen on startup.

> > RasPis do not have CMOS clocks.  So the startup step is huge.  
> Your recipe was from the command line.  That is not the startup case.

It is one of my startup cases.  For some definition of 'startup'.  I can
think of many different definitions of startup.  Pick one, pick them all.

> (unless the ntpd that you are killing never got started, or something
> like that)

OK, then we can call this case the "stop/start' or 'restart' case.  Fair

But that is partly why I'm trying to limit myself to smaller cases, like
minpoll=maxpoll=N, until those are understood.  Way too many random bad
things happening at startup to test them all apart right now.  Best to
focus on the statistically proveable cases first, slow goind, but harder
to argue with.  I find a minimum test is at least 24 hours, better yet
48 or more.

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