Arbitration Credit Feedback for On-Chip Bandwidth
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Solution Overview
Problem
In integrated circuits, existing arbitration schemes struggle to effectively manage transactions with varying priority levels in on-chip communications networks, leading to inefficient bandwidth utilization where lower priority transactions can consume resources at the expense of higher priority ones.
Innovation Solution
Implementing a method with multiple source paths and a single return path, where two arbiters independently arbitrate transactions based on address ranges and share information about transaction weights through a measurement circuit, updating credits for each transaction type to prioritize higher priority requests and prevent bandwidth consumption by lower priority requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional arbitration schemes are used where multiple arbiters independently manage transactions, then each arbiter can handle its own transactions, but lower priority transactions can consume bandwidth at the expense of higher priority transactions
Solution Approach 1:
The patent implements a feedback mechanism where the measurement circuit monitors transaction outcomes and updates credit values for different transaction types. This feedback loop allows the system to dynamically adjust arbitration weights based on observed bandwidth consumption patterns, preventing lower priority transactions from excessively consuming return path bandwidth while maintaining fair resource allocation across multiple arbiters
Solution Approach 2:
The system dynamically changes the credit parameter associated with each transaction type based on measured bandwidth usage. When lower priority transactions are observed to consume excessive bandwidth, their credit values are reduced, which automatically adjusts their arbitration priority in subsequent cycles. This parameter change mechanism enables adaptive bandwidth management without requiring complex centralized control
2Ease of operation
If multiple arbiters operate independently with separate credit management, then arbitration decisions can be made locally, but bandwidth optimization across the entire system cannot be achieved
Solution Approach 1:
The measurement circuit serves multiple functions: it monitors transaction outcomes for individual arbiters, aggregates system-wide bandwidth usage data, updates credit values for all transaction types, and provides feedback to all arbiters. This universal component enables coordinated bandwidth optimization across the entire system while maintaining the simplicity of local arbitration decision-making at each arbiter
Solution Approach 2:
The patent merges the credit management functionality across multiple independent arbiters by having them all reference a single shared credit value set maintained by the measurement circuit. This merging allows each arbiter to make independent decisions while collectively achieving system-wide bandwidth optimization, as the shared credit values ensure consistent priority enforcement across all arbitration points
Data Source
AI summary
A method and apparatus for arbitration. In one embodiment, a point in a network includes first and second arbiters. Arbitration of transactions associated with an address within a first range are conducted in the first arbiter, while arbitration of transactions associated with an address within a second range are conducted in the second arbiter. Each transaction is one of a number of different transaction types having a respective priority level. A measurement circuit is coupled to receive information from the first and second arbiters each cycle indicating the type of transactions that won their respective arbitrations. The measurement circuit may update a number of credits associated with the types of winning transactions. The updated number of credits may be provided to both the first and second arbiters, and may be used as a basis for arbitration in the next cycle.