[ntp:questions] best gps receiver for time synchronization

Uwe Klein uwe_klein_habertwedt at t-online.de
Thu Mar 12 09:47:59 UTC 2009

Kevin Oberman wrote:
> To get an idea of the fanaticism involved, several years ago, Kirk
> McKusick and my former boss here in Berkeley counted the machine cycles
> in the FreeBSD kernel for the PPS response(all done in the interrupt
> service routine) and used that to correct the time. Of course,in the
> days of 16 and 40 MHz systems, this was a bit more important.

Determinism has been lost.

Cache hits/misses, abitrated bus accesses, multicore contention, ...
All have cost determinism in latency. You can count cycles
but wont see the same count ever.


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