Talk at Stanford: Nanosecond-level Clock Synchronization in a Data Center

[Gary E. Miller]

Yo Achim!

On Fri, 17 May 2019 20:53:58 +0200
Achim Gratz via devel <devel at ntpsec.org> wrote:

> Hal Murray via devel writes:
> >> I'm not going to look at that stuff on YouTube… any link to
> >> oldfashioned non-multimedia?   
> >
> > Here is a Usenix paper that covers the same ground:
> >   https://www.usenix.org/system/files/conference/nsdi18/nsdi18-geng.pdf  
> 
> Ah, OK; the Huygens folks again.  That algorithm very much relies on
> the symmetry of the links, so for general NTP application it would
> need to be substantially revised.

Yes, but some good ideas in there.

I liked that the probes to a chimer come in pairs with a defined delay
between the first and second probe.  If the probes come back with a
similar inter-packet delay, then the probes are used.  If the delay is
skewed then the pair are discarded and retried.

The effect is that packets sent/received during interrupts, buffer bloat,
etc. can be discarded.  Leaving the remaing packets that have better
time properties.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  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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