Accurate distributed system time of day

An apparatus for synchronizing events across a plurality of neighboring processing nodes organized in a processing system, each processing node including an event incrementor, comprising:

• at least one local oscillator in the node running at a preselected frequency to increment the event incrementor;
• one of the nodes constituting a master node, and including a broadcast generator for broadcasting updates of an event by the master node to neighboring nodes and a register for counting a multiple of the preselected frequency;
• a broadcast transmitter responsive to the register to broadcast updates of the event by the master node, based on its event incrementor, via transmission paths to neighboring nodes;
• and
• a receiver in each neighboring node for comparing an update value received with its event incrementor value, responsive to the update received from the master node,
• wherein if the update value is smaller than the event incrementor value, then incrementing the event incrementor value at a fractional value of its normal incrementation until the update value is reached;
• and
• wherein the update value received is retransmitted to at least one of the nodes when the update value is no smaller than the event incrementor value.

An apparatus for synchronizing time-of-day events across a plurality of neighboring processing nodes organized in a distributed parallel processing system, each processing node including a time-of-day (TOD) incrementor, comprising:

• at least one local oscillator in a processing node running at a preselected frequency to increment locally the TOD incrementor;
• a controller for determining one of the processing nodes as a master processing node by transmitting an initialization packet to a selected processing node, and for transmitting at intervals a set TOD service packet to the selected master processing node;
• a broadcast generator in the master node, for broadcasting TOD update packets to neighboring processing nodes and a register for counting a multiple of the preselected frequency;
• wherein the broadcast generator includes a broadcast transmitter responsive to the register to broadcast TOD update packets, based an the TOD incrementor of the master processing node, via transmission paths to neighboring processing nodes,
• a receiver in each neighboring processing node for comparing a broadcast update packet value received with its TOD incrementor value, responsive to the broadcast update packet received from the master node, wherein if the broadcast update packet value is smaller than the TOD incrementor value, then incrementing the TOD incrementor value at a fractional value of its normal incrementation until the broadcast update packet value is reached;
• and
• wherein the update packet value received is retransmitted to at least one of the nodes when the update packet value is no smaller than the TOD incrementor value.

A computer readable medium containing program instructions for synchronizing events across a plurality of neighboring processing nodes organized in a processing system, each processing node including an event incrementor, comprising the instructions of:

• normally incrementing the event incrementor of each node off a local oscillator in the node running at a preselected frequency;
• designating one node as a master node;
• broadcasting updates of an event by the master node, based on its event incrementor, via transmission paths to neighboring nodes periodically at times that are a multiple of the preselected frequency;
• comparing, by the neighboring nodes, on update value received with its event incrementor value, responsive to the update received from the master node;
• and
• wherein if the update value is smaller than the event incrementor value, then incrementing the event incrementor value at a fractional value of its normal incrementation until the update value is reached;
• and
• wherein the update packet value received is retransmitted to at least one of the nodes when the update packet value is no smaller than the TOD incrementor value.