Replacing C

[Gary E. Miller]

Yo All!

On Mon, 9 Jan 2017 01:30:30 +0100
Kurt Roeckx <kurt at roeckx.be> wrote:

> > That said, I continue to admire your cut right to the heart of the
> > issue. ntpd spends enough time in I/O waits that I do not think
> > latency spikes will otherwise induce any problems above measurement
> > noise.  
> 
> The extra packet will improve the precision. It will eliminate
> one source of jitter.

Might be worth a try, but strange things happen at the micro Second level.

> And I guess there will be people who would
> want to use it, but now have to use PTP.

Now that is an interesting idea.  Could NTP hook into the hardware
level timestamps that PTP uses?

> They probably have the
> right hardware for it to be really useful.

Very finicky.  I've tried PTP on a number of different ethernet
chips.  Most chips do not support hardware PTP all.  Most chips that
say they support hardware PTP have weird bugs.  Only a few have really
worked for me.

Hard to fix too, since the problems are baked into the silicon.

> But I think in the general case, the jitter caused by the network
> will be higher than then what this would win.

Some network switches are smart enough to fast tack PTP packets, if
we can prove they are the bottleneck they could be fixed.

> But then I have no idea if someone actually tried something like
> this over the internet with standard hardware and what the effect
> of it is.

Then you can be the first.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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