Berkeleyalgoritmen

Berkeleyalgoritmen, commonly referred to as the Berkeley algorithm for clock synchronization, is a distributed method for aligning the real-time clocks of multiple processes in a networked system. It was developed at the University of California, Berkeley, during the 1980s as a practical solution for coordinating clocks among local-area workstations running Unix.

Operation consists of a designated coordinator periodically polling all participating processes to obtain their local clock values. After collecting the readings within a timeout, the coordinator computes a target time, typically by averaging the collected clocks and possibly excluding extreme values to mitigate the effects of outliers or network delays. The coordinator then informs each process of the adjustment needed to bring its clock toward the target time. Each process applies the given adjustment, and the set of clocks moves closer to synchronization.

Characteristics of the algorithm include a single trusted leader responsible for measurements and distribution of adjustments. It can tolerate some nonresponsive nodes by omitting them from the average. It does not rely on precise knowledge of network delays, making it robust to moderate timing jitter. Adjustments can be applied gradually or in bounded steps to avoid large instantaneous jumps.

Limitations involve the central coordinator creating a potential single point of failure and bottlenecks, limiting scalability in very large or dynamic systems. Compared with modern protocols like NTP or PTP, Berkeleyalgoritmen offers simplicity but less scalability and resilience to frequent topology changes.

History and context: the algorithm emerged from work at Berkeley as a straightforward approach to clock synchronization for local networks of workstations, emphasizing practicality and ease of implementation.