What's the best way to synchronize times to millisecond accuracy AND precision between machines?

Question

From what I understand, the crystals on PC's are notorious for clock skew. If clocks are always skewing, what is the best way to synchronize clocks between machines with millisecond accuracy and precision? From what I've found, NTP and PTP are possible solutions, but I was wondering if anybody had any experience on stackoverflow.com!

I understand NTP is the popular choice, but am wondering if anybody has had any experience with PTP (IEEE1588)

Answer 1

Just run the standard NTP daemon.

It does have options to take input from several GPS devices as well as talking to network servers.

Edit: I was referring to http://www.ntp.org/, not the one that comes with Windows.

I don't have any suggestion as to what NTP clients are best for windows, but for Unix machines there's no real reason to not run NTP.

Answer 2

Here's some 15-year-old software that syncs to within a hundredth of a millisecond. (My team wrote it when NTP wasn't good enough for our lab.)

From the conference paper's abstract: "A distributed clock for networked commodity PC's. With no extra hardware, this clock correlates sensor data from multiple PC's with latency and jitter under 10 microseconds average, 100 microseconds worst case."

Source code: https://github.com/camilleg/clockkit
(Until 2020 Feb 13 it was at http://zx81.isl.uiuc.edu/clockkit/, now offline.)