[ntp:questions] How to determin hardware latency for PPS offset given simple tools.
Paul G
bodosom at gmail.com
Thu Jun 20 19:48:10 UTC 2013
On Tuesday, June 4, 2013 3:44:19 PM UTC-4, E-Mail Sent to this address will be added to the BlackLists wrote:
> Is interrupt coalescing disabled on the gigabit ethernet adapters?
Not by me. I assume when ntpq reports symmetric delays proportional to interface speed that interrupts are not the issue for my question. Perhaps that's a poor assumption.
My question was -- given PPS clocks on the same network with ntpq offsets of:
0.021, 0.130, 0.064 and -0.046 -- any of which can be fudged away how do I determine the truth. That is how much is (consistent) hardware latency of any sort versus algorithmic restriction.
e.g. delay, offset and jitter from two sides of a gigE connection:
0.073 -0.008 0.002
0.064 0.011 0.006
Likewise fastE:
1.226 -0.059 0.076
1.104 0.109 0.068
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