DragonflyBSD kernel clock improvements

[Don Bowman]

> From: Bill Moran [mailto:wmoran at potentialtech.com]
> 
> Hello all,
> 
> I saw this recently:
> http://www.dragonflybsd.org/Docs/nanosleep/
> 
> I was wondering if anyone on the FreeBSD team has looked at 
> this.  It doesn't
> appear as if any recent change have been made in the FreeBSD 
> tree regarding
> this.
> 
> It's probably not a big deal, but I just thought I'd point it out.

I think its important, we do have some persistent time problems
(http://lists.freebsd.org/pipermail/freebsd-stable/2003-November/005194.html
)
which seem to require kern.timecounter.method=1 to work around.
I think an increased focus on clock accuracy and jitter can't
be a bad thing, even if FreeBSD is not a real time system.

increasing the repeatability is good for DEVICE_POLLING, for
tcp timers, etc. As more and more things move out from under the
giant lock, events can become increasingly deterministic.

Glad to see someone is putting a scientific method to the 
problem, it provides a good baseline for increasing the accuracy
of measurements.

--don