Frank Kardel and Simon Burge have worked on porting
the FreeBSD implementation of Poul-Henning Kamp's timecounters
to NetBSD-curren. Benefits of the framework are
true nanosecond support (within the limits of the hardware),
easier interfacing to hardware counters (as all scaling is
done on a machine independent level),
a new NTP "nanokernel" API, a simplified internal interface for the PPS API
and multiprocessing support.
for a lot more information including
the original timecounters paper,
the current status page and
details on the NTP nanokernel API.