Arbiter Delayed Weight-Reload Mechanism for Bandwidth Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication fabric arbitration schemes, such as deficit-weighted round robin, may falsely reload weights for sources operating at lower clock frequencies or with narrower interconnects, leading to inaccurate bandwidth distribution and performance issues.
Innovation Solution
Implementing a delayed weight-reload mechanism in the arbiter to prevent false reloads when a source is operating more slowly than the fabric, and using a secondary pointer to search for non-blocked transactions to improve bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard round robin arbitration scheme is used, then equal opportunity is provided to all sources, but sources operating at lower clock frequencies may experience false weight reloads and inaccurate bandwidth distribution
Solution Approach 1:
The arbitration scheme dynamically adjusts the weight reload timing based on the transaction history and clock frequency characteristics of each source. Instead of using fixed round robin intervals, the system adapts the arbitration cycle duration to match the operational speed of slower sources, preventing false weight reloads while maintaining fairness for faster sources.
Solution Approach 2:
The system changes the time parameter of weight reload operations based on detected source characteristics. When a slower source is identified, the weight reload timer is extended beyond the standard round robin cycle, allowing the slower source sufficient time to present transactions. This parameter adjustment ensures accurate bandwidth allocation without requiring complete redesign of the arbitration logic.
2Speed
If weights are reloaded immediately when exhausted, then the arbitration responds quickly to bandwidth allocation needs, but false reloads occur when sources operate more slowly than the fabric clock
Solution Approach 1:
The system performs preliminary detection of source operational characteristics before initiating weight reload operations. By monitoring transaction presentation rates and clock frequency relationships in advance, the arbitration logic determines whether an immediate weight reload is appropriate or if a delayed reload is needed to avoid false positives from slower sources.
Solution Approach 2:
The arbitration scheme incorporates feedback from the transaction arbitration outcomes and source activity patterns. When a source consistently fails to present transactions at the expected rate, the system feeds this information back to the weight management logic, which then adjusts the reload timing accordingly. This feedback mechanism prevents false weight reloads while maintaining responsive arbitration for active sources.
Data Source
AI summary
In an embodiment, an arbiter may implement a deficit-weighted round-robin scheme having a delayed weight-reload mechanism. The delay may be greater than or equal to a ratio of the fabric clock to a slower clock associated with one or more sources that have no transactions but that have unconsumed weights (or another measure of difference in transaction rate). If a transaction is provided from the one or more sources during the delay, the reload of the weights may be prevented. In some embodiments, the arbiter may be augmented to improve usage of the bandwidth on an interface in which some transactions may be limited for a period of time. The arbiter may implement a first pointer that performs round robin arbitration. If the first pointer is indicating a source whose transaction is temporarily blocked, a second pointer may search forward from the current position of the main pointer to locate a non-blocked transaction.