[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [gpsd-dev] PPS over USB

From: Ed W
Subject: Re: [gpsd-dev] PPS over USB
Date: Tue, 08 May 2012 08:38:37 +0100
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:12.0) Gecko/20120428 Thunderbird/12.0.1

On 08/05/2012 08:15, Eric S. Raymond wrote:
Hal Murray<address@hidden>:
One of the explicit goals of the Cosmic Backround Bufferbloat Detector is to
sanity-check NTP.
If you see anything that seems unreasonable, please let me know.  ntpd has a
huge collection of heuristics (hacks?) that try to filter out all sorts of
quirks/glitches.  I'm sure there are some cases that will get past the
current filters.
Oh trust me, if we find such phenomenae we are *not* going to be merely
whispering about them - you and every other Internet infrastructure geek
we know will get the A-OOGA A-OOGA red alert muy pronto. :-)

I would have expected the kinds of problems you are describing above to be more easily studied/tested using models in a lab? Just turn on the various traffic shaping options and you can make your connection appear to be dropping packets/arbitrarily slow/turn up congestion. I have a script that we use to pretend to be on an Iridium satellite dialup, ie 2.4Kbits, ie 300 bytes per second - for sure we test everything over a real connection, but it sure is helpful to be able to stress things in certain ways

I don't really follow ntp development, but what I really like about chrony is every time you "have an idea" Miroslav agrees or disagrees with a whole bunch of investigative action and usually a graph or two. He really loves to go to the field and show the results! He is also the chap who published some interesting numbers comparing the accuracy and offsets of a large number of machines in

Good luck

Ed W

reply via email to

[Prev in Thread] Current Thread [Next in Thread]