Raspbery Pi is not really capable of being a serious time server out of the box (astronomical jitter) though it is fun to play with. I imagine that it would be

Raspbery Pi is not really capable of being a serious time server out of the box (astronomical jitter) though it is fun to play with. I imagine that it would be possible to greatly improve it with some creative bare-metal or RTOS implementation, but in Linux the Pi is really just too unpredictable to do the job well. That is not to say that it's useless though; a Pi running Stratum 1 with GPS time is still going to be heaps better than anything you can get from a Stratum 2 server syncing over the public internet. For serious DIY players, BeagleBone hardware has both hardware timestamping on ethernet and hard realtime IO capabilities through the PRU interface (used for PPS signal from your GPSDO). It makes a ridiculously superior (orders of magnitude) time server compared to Rpi.