I think NTP usually synchronizes the system time, so programs don't have to use any NTP specific API to get NTP time. PTP won't help here: all it does is increa

I think NTP usually synchronizes the system time, so programs don't have to use any NTP specific API to get NTP time. PTP won't help here: all it does is increase the accuracy from milliseconds to microseconds - not much use if the Linux scheduler tick is 1ms. PTP time is mainly useful together with hardware event timestamping, where stuff like interrupt latency can be excluded. If you want, for example, to send a frame every two seconds as soon as the device boots, you still should use CLOCK_MONOTONIC, otherwise you produce a glitch when PTP ramps up.