I would also like to know how to best tweak the Raspberry Pi 2 for best
performance as an NTP server. Although I have been using Linux-based
firmware in my routers for several years now, I have never actually
worked In Linux before.
I have gone through several tutorials on compiling a custom kernel, only
one or two have actually ended in a compilation, but then I couldn't
figure out where the kernel and modules were and get them onto the Pi. I
have tried this under Ubuntu x64, Debian x64, and Mint 32 bit. So far
Mint has been the best, I successfully compiled and I found the kernel,
but cannot figure out where the modules are. Anybody suggest a really
nice tutorial for learning this Linux stuff? My experience so far is
really leading me to appreciate Windows.
Thanks
Ed
On 6/12/2015 9:55 AM, Cube Central wrote:
Hi Max! Thanks for the information, I was wondering if you had documented what
you did to your Raspberry Pi so that it might be reproducible to someone like
me (a newcomer time-nut and intermediate Linux user) ... you had said:
"Here is what I have been able to do with a Motorola Oncore UT+ that I got from Bob
Stewart awhile back. This is with a Raspberry PI 2 with a number of tweaks and a custom
compiled kernel. Nothing too drastic... plus the current Dev version of NTP compile on
the Raspberry PI."
What tweaks? What options have you compiled? What are the gritty details of
your setup?
"I'm getting better results letting ntpd discipline the clock over doing kernel
discipline...
not surprising because the algorithms in the ntpd code are much more sophisticated
than the Linux kernel pps code... ntpd discipline provides much lower jitter in my
experience."
what setting is this and how might I go about experimenting with it? Is that the "flag3"
option in the "Generic NMEA GPS Receiver" documented here?
https://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html
<snip>
"Not too shabby for a killer deal on an Oncore UT+ for $5 from Bob! I'm running the
PPS out of the UT+ through a level converter to get the ~3.3v PPS output... the serial
output on the UT+ is also going through a level converter direct into the Pi 2. Using
the oncore 127.127.30.0 ntpd driver and again, i'm not using hardpps kernel
discipline."
I see word HARDPPS in the driver you mentioned
(https://www.eecis.udel.edu/~mills/ntp/html/drivers/driver30.html ) but that
documentation is a bit scarce... Could you fill me in on how you have it set up? Is the
PPSAPI also used for the "Generic NMEA GPS Receiver" (driver 20) or the PPS
driver (driver 22)?
Thanks so much for your assistance! Sorry if these questions have been posted
before, but I am very curious about your setup as it nearly matches mine!
-Randal "r3" of CubeCentral
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