Ring Interconnect Message Arbitration via Activity Indications
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Solution Overview
Problem
In ring interconnect systems, nodes with a large number of messages to transmit can indefinitely prevent messages from downstream nodes from being transmitted, leading to service starvation and denial of service due to the priority given to messages already on the ring.
Innovation Solution
Each node in the ring interconnect system is connected to two other nodes via inter-node paths distinct from the ring, equipped with message buffers, activity level circuitry to transmit activity indications based on buffer occupancy, and arbitrator circuitry to allow ingress of messages onto the ring based on these indications, ensuring fair bandwidth allocation and preventing service starvation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If messages already present on the ring interconnect take priority over messages entering the ring, then message transmission efficiency is improved, but nodes with large numbers of messages can indefinitely prevent downstream nodes from transmitting, causing service starvation
Solution Approach 1:
The patent applies preliminary action by having each node send an activity indication signal to downstream nodes before actually injecting messages onto the ring. This advance notification allows downstream nodes to prepare and ensures that even if a node has many messages, it cannot indefinitely block downstream nodes because the activity indication mechanism provides a way for downstream nodes to know when to expect messages and plan accordingly. The arbiter at each node uses these preliminary indications to control message injection timing.
Solution Approach 2:
The patent implements feedback through the activity indication signal that flows downstream around the ring. Each node monitors these signals to understand the activity state of upstream nodes. This feedback loop allows the system to dynamically adjust message injection decisions based on current ring conditions, preventing any single node from indefinitely blocking downstream nodes while maintaining efficient message transmission when conditions are favorable.
2Productivity
If activity indications are transmitted via dedicated inter-node paths separate from the ring interconnect, then bandwidth of the ring interconnect is preserved for messages, but the system complexity increases due to additional dedicated paths
Solution Approach 1:
The patent extracts the activity indication signaling function from the main message transmission path by implementing dedicated inter-node paths separate from the ring interconnect. This separation allows the activity indications to be transmitted without consuming宝贵的 ring bandwidth, as they travel through dedicated control paths. The extraction of this control function into separate infrastructure resolves the bandwidth conflict while the systematic implementation keeps complexity manageable.
Solution Approach 2:
The dedicated inter-node paths act as intermediaries between nodes for transmitting activity indications. Rather than using the ring interconnect itself for this control signaling, the patent introduces separate intermediary paths that mediate the control information flow. This intermediary infrastructure protects the main ring interconnect from being used for control signaling, preserving its bandwidth for actual message transmission.
Data Source
AI summary
A ring interconnect system comprises a plurality of nodes. Each node is connected to two other nodes to form a ring interconnect. Every pair of nodes is connected by an inter-node path for that pair of nodes distinct from the ring interconnect. Each of the nodes comprises a message buffer to buffer messages received from at least one device associated with the node. Each of the nodes also comprises activity level circuitry to transmit an activity indication, when a number of the messages in the message buffer is equal to or above a threshold, to each other node of the plurality of nodes via the respective inter-node paths. Each of the nodes also comprises arbitrator circuitry to receive the activity indications from each other node and from the activity level circuitry, and to allow ingress of a message from the message buffer onto the ring interconnect in dependence on the activity indications. Also provided is a method of operating a node of a ring interconnect system.