[LinuxPPS] PLL sensitivity

[Udo van den Heuvel]

Remco den Besten wrote:
(....)
> When the system is 'disturbed' e.g. by temperature or CPU load, FreeBSD 
> shows one overshoot and is
> almost immediately 'back into business' (whereas Linux needs a lot of time 
> to recuperate (see today on
> remco.org/ntp)) and the magnitude of the effect of the disturbance (e.g. the 
> offset, or how precise your
> time stamps are) is much bigger with Linux than FreeBSD under the same 
> circumstances.

OK, I see.

> I just googled on time_pps_kcbind() (which is not implemented in LinuxPPS, 
> see
> https://lists.ntp.org/pipermail/hackers/2008-October/003899.html) and saw 
> that this posting
> also refers to the issue I want to raise.
> 
> From: "Udo van den Heuvel"
>>> synchronized by an external (PPS) reference, but perhaps some smoothing 
>>> can
>>> be achieved by experimenting
>>> with the PLL filter(s) (e.g. timing contstants) like PI-regulation
>>> (proportional/integral algorithms)?
>> These PLL filters are in ntpd or in kernel? 

At the url you posted I read:

 As an aside, time_pps_kcbind() may be optional, but it isn't
 terribly difficult to implement. You do yourself a disservice by
 not suporting it, IMO.

So Rodolfo, what do you say?

Kind regards,
Udo