[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:
> Also:
>  http://phk.freebsd.dk/soekris/pps/
> H

More information about the questions mailing list