the Huygens algorithm is also worth a look
https://www.usenix.org/system/files/conference/nsdi18/nsdi18...
https://www.usenix.org/system/files/conference/nsdi18/nsdi18...
The authors’ work forms the basis of what the team at Clockwork.io is building, enabling accurate one-way delay measurements (rather than just RTT/2) that improve latency visibility and telemetry across CPU and GPU infrastructure