I’ve been working on measuring NTP (and PTP) timing accuracy in Linux for the past month or two, and I’m finally down to what I think is the very end. I’ve demonstrated that NTP (using Chrony) can sync to within ~500 ns on a non-trivial network. By all accounts, ptp4l is able to do better than that, at least when all of the switches and NICs involved have hardware support for PTP. At some point, though, it’s very difficult to trust network time syncing software’s estimates of their ...
