Re: Clarifications about PPS SHM content

[Gary E. Miller]

Yo Paul!

On Thu, 26 Mar 2020 12:48:00 -0700
Paul Theodoropoulos via <address@hidden> wrote:

> >> In my experience, at least on RPI 2 at least, ntpheat introduced
> >> too much secondary 'noise' for lack of a better term - since rpi2
> >> can only bounce between 600Mhz and 1.4Ghz,  
> > Makes sense.  ntpheat was designed on a RasPi 3.  So not a problem.
> >  
> 
> Apologies - my units are RPI 3B+. The 3B+ only supports those two 
> frequencies - no scaling between them- and that's the source of the
> added 'noise'.

That is a limitation of your setup, not of the Raspberry Pi or the
kernel it runs.  My RasPi's have no problem with intermediate
CPU frequencies.

I have also heard of people using the GPU to control the PCB temp.
that does not affect the CPU latency.

> Either way, in ascending order of stability - all other things being
> equal 
> -__ I would say:
> 
> freewheeling temps - lowest
> ntpheat - better
> insulated environment - best

ntpheat and insulated environment are not mutually exclusive.  I go
further and add a RasPi controlled 7W light bulb in the "insulated"
environment.

So, the best is an insulated case, with a temp controlled interior,
with ntpheat adjusting the RasPi PCB temp.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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