Arbitration Circuit Priority Cancellation Mechanism
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Solution Overview
Problem
In multi-bus arbitration systems, high-priority transactions are often delayed as they wait for the completion of low-priority transactions, leading to inefficient use of bus resources and reduced performance due to the lack of a mechanism to cancel and prioritize transactions effectively.
Innovation Solution
An arbitration circuit with a first-in-first-out buffer and a control circuit that monitors transactions and cancels low-priority transactions to allow high-priority transactions to be executed immediately, utilizing a second buffer to manage and prioritize transactions based on priority levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data transfers for all requests are executed in parallel when no conflict is detected, then bus utilization is improved, but high-priority requests may be delayed waiting for low-priority requests to complete
Solution Approach 1:
The patent introduces a monitoring mechanism that detects high-priority requests in advance before they are fully processed. When a high-priority request is detected, the system proactively cancels ongoing low-priority transactions and redirects the bus to the high-priority request, preventing delay rather than reacting after the fact.
Solution Approach 2:
The arbitration circuit incorporates a monitoring mechanism that continuously observes the buffer contents and request priorities. This feedback loop enables the system to detect when a high-priority request is present and automatically adjust the transaction execution sequence, canceling low-priority requests if necessary to prioritize high-priority ones.
2Speed
If low-priority requests are canceled to prioritize high-priority requests, then high-priority request execution is improved, but system complexity increases due to cancel mechanisms
Solution Approach 1:
The patent introduces a dedicated monitoring mechanism as an intermediary component that sits between the buffer and the arbitration logic. This monitoring mechanism simplifies the overall system by centralizing the priority detection and cancel request generation functions, making the complexity localized rather than distributed throughout the arbitration circuit.
Solution Approach 2:
The arbitration circuit is segmented into distinct functional components: a monitoring mechanism that detects priority conditions, a buffer that stores transaction information, and an arbitration logic that executes cancel requests. This segmentation allows each component to be optimized independently and simplifies the overall design by dividing the complex arbitration function into manageable modules.
3Loss of time
If high-priority transactions are executed immediately by canceling low-priority ones, then processing delay is reduced, but loss of information occurs when cancel requests fail
Solution Approach 1:
The patent introduces a buffer that stores transaction information before execution. This buffer acts as a cushion that protects against information loss: if a cancel request fails, the original transaction data remains preserved in the buffer and can be re-transmitted, ensuring no permanent data loss occurs during the priority arbitration process.
Data Source
AI summary
In an arbitration circuit, transactions output from a plurality of master circuits are stored in a first-in-first-out type first buffer, and when a high-priority transaction higher in priority than one of the stored transactions is output from one of the plural master circuits, a cancel request of a low-priority transaction lower in priority than the high-priority transaction, out of the stored transactions, is output to a second buffer in a slave circuit, and when the cancel request is successful, the high-priority transaction is output to the slave circuit, and after the high-priority transaction is output to the slave circuit, the low-priority transaction whose cancel request is successful is output to the slave circuit.