[traceroute66]

Am I missing something? The FB blog proudly states how they improved accuracy "10 milliseconds to 100 microseconds".

Surely that's a lot of effort that anybody with in a datacentres with decent connectivity could replicate with a Chrony instance ?

100 microseconds is 0.0001 seconds, right ?

Seems to be something Chrony can do with its eyes closed:

System time : 0.000003297 seconds slow of NTP time Last offset : +0.000000549 seconds

There are lots of great NTP servers out there hosted by trusted parties such as national time labs. Most people don't need fancy GPS hardware (and the expense of paying someone for roof access to put your antenna !). If you've got good software and good connectivity you can replicate 99.999% of the same thing.