[time-nuts] Comparing the BeagleBone Black & Raspberry Pi as NTP servers

Paul tic-toc at bodosom.net
Sun Mar 22 16:41:56 EDT 2015

On Sat, Mar 21, 2015 at 12:23 PM, David J Taylor <
david-taylor at blueyonder.co.uk> wrote:

> I've just put up my first draft of a comparison of these two popular
> devices as NTP servers:
> Comments welcomed - I know it's an imperfect test!
> ...

Perhaps there are some services or background tasks I can disable to reduce
> the CPU steady load from its present 16% average level?

There's not enough background to offer good advice but here's some "okay"

1) Did you start out using the attached patch antenna?  D Drown implies
successfully using the patch on the Adafruit until it was soldered in
place.  He fixed that by switching to an external antenna.  I've never had
any success with attached patch antennas but my receivers are inside.

2) I've attached the output of pstree for my NTP BBB.  That machine is
typically 97% idle (load average 0 to .005) unless I run the PPS blinker
which is written in Python.  It is running the heartbeat blinker that
sleeps almost all the time.

3) I run R. C. Nelson's builds of Ubuntu (Server) which do start Apache by
default but it's easy to turn off.

4) I don't understand the section labelled "The view from afar".  You say
you're measuring two machines but there are many lines of output.  Perhaps
you could discard the data that's not related to the machines under test.

Compared to my primary clock via peerstats:
BBB mean offset 7.8e-6, mean jitter 7.0e-6
RPi mean offset 7.1e-5, mean jitter 5.3e-5
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