Network-on-Chip Arbitration Using Weightage Lookup Tables
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Solution Overview
Problem
Existing network-on-chip (NoC) arbitration methods fail to effectively handle combinations of different priority levels within the same router virtual channel, leading to inefficiencies in flit transmission and congestion control.
Innovation Solution
A method and system for NoC arbitration that computes default and elevated bandwidths and weights for virtual channels, generates a weightage lookup table, and uses deficit interleaved weighted round-robin arbitration to select flits based on user input, ensuring optimal routing and uninterrupted transmission across the NoC, while allowing reconfigurable QoS implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing NoC arbitration methods are used, then flit transmission can be controlled, but they fail to effectively handle combinations of different priority levels within the same router virtual channel
Solution Approach 1:
The patent segments the arbitration process into multiple stages: first-stage arbitration selects virtual channels based on priority levels, and second-stage arbitration selects egress links within selected virtual channels. This segmentation allows different priority levels to be handled systematically without interfering with each other, resolving the contradiction between adaptability to multiple priority levels and reliable flit transmission.
Solution Approach 2:
The patent applies local quality by assigning different arbitration weights and bandwidth allocations to different priority levels and virtual channels. Each virtual channel has customized arbitration parameters based on its priority level, enabling differentiated service while maintaining overall system reliability. High-priority channels receive higher weights and guaranteed bandwidth, while lower-priority channels share remaining resources.
2Reliability
If weighted arbitration is implemented to provide QoS, then congestion control is improved, but the complexity of arbitration logic increases
Solution Approach 1:
The arbitration logic is segmented into two independent stages with distinct functions. The first stage handles virtual channel selection based on priority, while the second stage handles egress link selection within selected channels. This segmentation reduces the complexity of each individual stage while maintaining comprehensive QoS control capability.
Solution Approach 2:
The patent performs preliminary action by pre-calculating and storing arbitration weights and bandwidth allocations in lookup tables before actual arbitration occurs. During runtime, the arbitration logic simply retrieves pre-computed values from these tables, significantly reducing the computational complexity of real-time arbitration while maintaining effective congestion control.
3Productivity
If priority elevation of flits is allowed, then QoS for high-priority traffic is improved, but it creates complex interactions between different priority levels in the same virtual channel
Solution Approach 1:
The patent segments the arbitration process to handle priority elevation systematically. In the first stage, flits are classified by priority level and routed to appropriate virtual channels. In the second stage, arbitration occurs within each virtual channel using pre-established weightings. This segmentation isolates priority elevation effects to specific stages, preventing complex interactions across different priority levels.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting arbitration weights and bandwidth allocations based on priority levels. When flits with different priority levels interact in the same virtual channel, the arbitration parameters (weights, minimum bandwidth guarantees) are changed to reflect the priority differences, enabling QoS improvement without creating unmanageable complexity.
Data Source
AI summary
A method comprises the steps of receiving input from a user via user interface and selecting a plurality of flits from a plurality of ingress into a plurality of virtual channels followed by selecting the flits from the virtual channels into a plurality of egress based on the input from the user. The selection of the flits into the virtual channels and the egress characterized by the steps of computing default and elevated bandwidths of the virtual channels, computing default and elevated weights of the virtual channels based on the default and elevated bandwidths and generating a weightage lookup table using the default and elevated weights to perform arbitration weightage lookup for the flits with default and elevated priority levels for selecting the flits into the virtual channels and the egress, wherein the flits from the different ingress comprise different default and elevated weight.