ntpq flakiness

Eric S. Raymond esr at thyrsus.com
Wed Apr 10 22:12:32 UTC 2019


Hal Murray <hmurray at megapathdsl.net>:
> Thanks.
> 
> There is another quirk that seems related to retransmissions.  I forget the 
> details.  I'm pretty sure there is bug report on it.
> 
> 
> > I do remember that there was a very old issue with flaky behavior of ntpq
> > over WiFi that we thought might be due to a bug in the fragment reassembly
> 
> If I interpret "WiFi" as lost packets, that fits in with the other collected 
> observations.

You reported lost packets happening over WiFi links, yes.

> My guess is that this new quirk is just what happens with "peers" when lots of 
> packets get lost and we just haven't seen it enough before now to get reported.

I don't think you're wrong.

Nonreproducible bugs suck.  When you reported the original flakiness
over WiFi I nodded, thinking I knew where the problem was likely to be,
and dove into the packet reassembly code looking for an off-by-one bug
or something.

It's one of the few times I've gone on an expedition like that and
completely failed.  Whatever it is, it's not going to be obvius.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>




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