Accurate distributed system time of day

摘要

Apparatus for synchronizing time-of-day events across a plurality of neighboring processing nodes organized in a distributed parallel processing system with each processing node including a time-of-day (TOD) incrementor. The TOD incrementor of each processing node is coupled to a local oscillator in the processing node running at a preselected frequency to increment locally the TOD incrementor. A controller determines one of the processing nodes as the master processing node by transmitting an initialization packet to the selected processing node, and transmits a set TOD service packet to the selected master processing node. The master processing node includes a broadcast generator that broadcasts TOD update packets to neighboring processing nodes. A register in the master processing node counts a multiple of the preselected frequency. The broadcast generator in the master processing node includes a broadcast transmitter responsive to the register, to broadcast TOD update packets, based on the TOD incrementor of the master processing node, via transmission paths to neighboring processing nodes. A receiver in each neighboring processing node updates its TOD incrementor responsive to a broadcast update packet received from the master processing node.