[ntp:questions] Red Hat vote for chrony

Charles Swiger cswiger at mac.com
Mon Dec 8 00:00:57 UTC 2014

On Dec 7, 2014, at 12:47 PM, Paul <tik-tok at bodosom.net> wrote:
> On Sun, Dec 7, 2014 at 2:42 PM, Charles Swiger <cswiger at mac.com> wrote:
>> ... Heck, even today's modern smartphone has an
>> AGPS chip and more horsepower than a ~2002-era Soekris with an embedded CPU.
> I have no idea what you're talking about but "horsepower" is not relevant.

Oddly enough: if I have no idea what someone was talking about, I don't assume
that what they said could not possibly be relevant.

>> If you want to use PTP for timestamping, rather than a PPS signal over a
>> GPIO pin, parallel/serial port, fine.  What PTP time source did you have in mind?
> As as been pointed out to you by others you can't measure error using the network unless you remove the network error.  That's why you would use PTP but as also noted measuring across the network is the wrong answer.  I wasn't suggesting using PTP.  I said it tries to solve "*one* of the tings you have to deal with".

You've told me one thing that you wouldn't use.

That doesn't answer the question of what you would use.

>>> Maybe you're also unfamiliar with what NTP is doing:  It disciplines a virtual (system) clock which is derived from the on-board (usually uncompensated) crystal.
>> I've been providing NTP stratum-1 or -2 timeservice to the public since the late 80's.
>> Nevertheless, you're welcome to patronize me about my limited knowledge of NTP if you
>> at least have a productive point to make by doing so.
>  And I've been doing it since you could peer with fuzzballs.  Driving to work every day for 30 years doesn't make you an automotive engineer.

Right, and your point was?

Pretend you wanted to explain what you meant by this to an neutral third party.

>>> The big problem is temperature induced wander and that's something (back to RedHat and Chrony) Chrony claims to do better.
>> Yes, ntpd and chrony will notice temperature changes causing a frequency drift,
> You don't need to repeat approximately what I said back to me. 

I was attempting to find some level of agreement about basic facts.

> Back to your favorite source: <http://phk.freebsd.dk/time/20141026.html>
> but you won't read it so:

WTF is that supposed to mean?

> "The reason most crystals don’t behave that way, is that people usually don’t put a 100W variable heating element right next to them.
> If you look at the horizontal part, you can see a lot of small wiggles, that is the aircondition cycling on and off.
> Around 5000 seconds, there’s a dip, that’s me using the machine to crunsh a couple of gigabytes of data, and the heat from the CPU affects the crystal."
> The 100W heater is the CPU by the way.

I've either read my supposed favorite source already and/or or not read it.

100W CPU under load causes XO drift.  And so?
> And as long I we're providing pointless qualifications:

Um, wow.  Did you fail to stroke your ego in private today?

Dude, unless I want to hire somebody, I generally don't care any more about
someone else's qualifications than I care about what they think of mine.

>> If a $1500 PRS-10 is out-of-bounds even for measurement purposes against a
>> ~$250 embedded system + GPS puck
> I have a PRS-10 and s GPSD(D)OCXO system.  I even have a decent counter and scope.  I didn't say it was out of bounds for measurement I said the opposite.  Are you one of those opposite guys?  If I say X are you going to say I said not-X?

If we're talking about data, if X is right, then I'm hopefully going to say X is right.

> [ ... ]
> "Without measuring the
> local clock against some other clock or oscillator which is known to be
> accurate to sub-microsecond levels, one doesn't have the data needed to draw
> conclusions about the actual timekeeping precision."
> I (sort of) agree with you but nothing you've said addresses that issue.  But you don't have to believe me.  Just pay attention to any of the people that have tried to point out your errors.

And what errors would these be?


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