1589: A Kernel Model for Precision Timekeeping.

This memorandum describes a model and programming interface for generic operating system software that manages the system clock and timer functions. The model provides improved accuracy and stability for most workstations and servers using the Network Time Protocol (NTP) or similar time synchronization protocol. This memorandum describes the principles of design and implementation of the model. Related technical reports discuss the design approach, engineering analysis and performance evaluation of the model as implemented in Unix kernels for Sun Microsystems and Digital Equipment workstations. The NTP Version 3 daemon xntpd operates with these implementations to provide improved accuracy and stability, together with diminished overhead in the operating system and network. In addition, the model supports the use of external timing sources, such as precision pulse-per-second (PPS) signals and the industry standard IRIG timing signals. The NTP daemon automatically detects the presence of the new features and utilizes them when available.