The Nanokernel

Dave L. Mills, and Poul-Henning Kamp <</span>&gt;, &lt;<span class="author-email">>

Internet timekeeping has come a long way since first demonstrated almost two decades ago. In that era most computer clocks were driven by the power grid and wandered several seconds per day relative to UTC. As computers and the Internet became ever faster, hardware and software synchronization technology became much more sophisticated. The Network Time Protocol (NTP) evolved over four versions with ever better accuracy now limited only by the underlying computer hardware clock and adjustment mechanism. The clock frequency in modern workstations is stabilized by an uncompensated quartz or surface acoustic wave (SAW) resonator, which are sensitive to temperature, power supply and component variations. Using NTP and traditional Unix kernels, incidental timing errors with an uncompen- sated clock oscillator is in the order of a few hundred microseconds relative to a precision source. Using new kernel software described in this paper, much better performance can be achieved. Experiments described in this paper demonstrate that errors with a modern worksta- tion and uncompensated clock oscillator are in the order of a microsecond relative to a GPS receiver or other precision timing source.