[ntp:questions] Onboard Local Oscillator Change Improvements
David L. Mills
mills at udel.edu
Mon Oct 8 20:06:13 UTC 2007
The performance with ntpd running in a rusting Pentium hulk with several
hundred clients and PPS is surprisingly good. Our rackety.udel.edu runs
FreeBSD 6.1 with PPS via the parallel port. It usually shows residual
offset and jitter in the order of a few microseconds. It is good enough
that the daily variations in the air-conditioned machine room
temperature can be measured accurately.
Measuring the PPS offset within a few hundred nanoseconds is brilliant;
however, the measured latency to read the system clock from an
application is in the order of a microsecond and this polluted by
context switches, cache misses, timer interrupts, etc.
Harlan Stenn wrote:
More information about the questions