Bufferless routing in on-chip interconnection networks

A system that includes an on-chip interconnection network, the on-chip interconnection network to perform acts comprising:

• receiving two or more flow control digits (flits) at an input port of an on-chip router:
• ranking the two or more flits within the on-chip router;
• prioritizing the two or more ranked flits within the on-chip router;
• sending one or more of the prioritized flits over a productive output port of the on-chip router when the productive output port is available, the productive output port providing a shorter path to a destination of the flit than a non-productive output port;
• deflecting the one or more prioritized flits over the non-productive output port of the on-chip router when the productive output port is unavailable;
• computing a route of the flit at the first on-chip router;
• sending lookahead information including the route of the flit from the on-chip router to a second on-chip router via a lookahead link during the traversal of a portion of the on-chip router by the flit;
• determining whether a particular flit of the prioritized flits is a head-flit or a body-flit of a worm, the worm comprising a sequence of related flits that includes the head-flit and one or more body-flits;
• and
• when an unallocated productive output port is available, assigning the head-flit to an unallocated productive output port.

A memory device including instructions that are executable by processing logic to perform acts comprising:

• receiving a flow control digit (flit) at an input port of a first on-chip router, each on-chip router in the on-chip interconnection network comprising a number of output ports greater than or equal to a number of input ports, the output ports in communication with other on-chip routers, each on-chip router reachable from every other on-chip router via one or more on-chip network connections;
• ranking the flit within the first on-chip router;
• prioritizing the ranked flit to a prioritized output port among the output ports of the first on-chip router;
• sending the flit towards a destination via the prioritized output port;
• computing a route of the flow control digit (flit) at the first on-chip router;
• sending lookahead information containing the route of the flit to a second on-chip router via a first lookahead link between the first on-chip router and the second on-chip router while the flit traverses the switch in the first on-chip router;
• computing the route of the flit at the second on-chip router using the lookahead information from the first on-chip router while the flit traverses a network connection link from the first on-chip router to the second on-chip router;
• and
• sending lookahead information containing the route of the flit to a next on-chip router via a second lookahead link between the second on-chip router and the next on-chip router while the flit traverses the switch in the second on-chip router.

A method of local flow control of flow control digits (flits) in an on-chip interconnection network, the method comprising:

• receiving a flow control digit (flit) at an input port of a first on-chip router, each on-chip router in the on-chip interconnection network comprising a number of output ports greater than or equal to a number of input ports, the output ports in communication with other on-chip routers, each on-chip router reachable from every other on-chip router via one or more on-chip network connections;
• ranking the flit within the first on-chip router;
• prioritizing the ranked flit to a prioritized output port among the output ports of the first on-chip router;
• sending the flit towards a destination via the prioritized output port;
• computing a route of the flit at the first on-chip router;
• sending lookahead information including the route of the flits from the first on-chip router to a second on-chip router via a lookahead link while the flits traverse a first switch in the first on-chip router;
• allocating a designated output port to a worm comprising a sequence of related flits;
• and truncating a lower ranking worm previously allocated to the designated output port.