Dave,
I'm glad it's gone, as the code was never intended to measure
resolution. It is intended to measure precision, defined in the
specification as the time to read the system clock. This turns out to
be really important for a client to read two or more sources on the same
fast Ethernet. The intent is to avoid non-intersecting correctness
intervals.
Dave
Dave Hart wrote:
On Thu, Sep 16, 2010 at 1:23 AM, David L. Mills <mi...@udel.edu> wrote:
Miroslav,
The fastest machine I can find on campus has precision -22, or about 230 ns.
Then, I peeked at time.nist.gov, which is actually three machines behind a
load leveler. It reports to be an i386 running FreeBSD 61. Are you ready for
this? It reports precision -29 or 1.9 ns! I'm rather suspiciousabout that
number.
I think this can be attributed to some code that used to be in ntpd
which, on FreeBSD only, used for precision an OS estimate of the clock
resolution in place of the measured latency to read the clock used on
every other platform. That FreeBSD exception was removed from ntpd
years ago, but apparently after the version in use by NIST.
Dave Hart
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