[ntp:questions] linux kernel pps support on raspberry pi

folkert folkert at vanheusden.com
Thu Dec 18 13:47:57 UTC 2014


They are not overclocked. These are B-boards.

On Wed, Dec 17, 2014 at 12:56:33PM -0800, A C wrote:
> Is the Rpi overclocked?  When overclocked it will dynamically change the
> CPU frequency.  You could potentially underclock it or heatsink the SoC
> to keep the CPU frequency from changing.
> 
> Also, which version of the RPi?  A, B or B-plus?
> 
> On 2014-12-17 12:22, folkert wrote:
> > This is about receiving a pps signal via one of the gpio pins of the
> > raspberry pi and then feeding it to ntp.
> > 
> > Did a test for a while: every 5 minutes I would look at the output of
> > ntpq -c pe -n for jitter of the pps source.
> > This pps source was "measured" either in the kernel (this newly added
> > gpio pps support in the raspberry pi) or in user space using my own
> > rpi_gpio_ntp.
> > 
> 
> > 
> > TL;DR:
> > - kernel   : 13.2us jitter on average
> > - userspace:  9.6us jitter on average
> > 
> > 
> > Folkert van Heusden
> > 
> 
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions


Folkert van Heusden

-- 
Multitail est un outil permettant la visualisation de fichiers de
journalisation et/ou le suivi de l'exécution de commandes. Filtrage,
mise en couleur de mot-clé, fusions, visualisation de différences
(diff-view), etc.  http://www.vanheusden.com/multitail/
----------------------------------------------------------------------
Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com


More information about the questions mailing list