Arbitration Table to Count Value Conversion for Resource Distribution
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Solution Overview
Problem
As arbitration tables grow in size, the resulting hardware state machines require exponentially more gates, leading to increased latency and inefficiency in resource distribution, particularly in systems like PCI Express where multiple entities compete for limited bandwidth.
Innovation Solution
Converting a 32-Phase Weighted Round Robin arbitration table into 5-bit count values eliminates the need for a hierarchy of comparators, simplifying the logic and reducing latency by using seven 5-bit counters to manage port arbitration, allowing for linear scalability and non-blocking transfers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large arbitration table is used to handle multiple resource requests, then the resource distribution capability is improved, but the hardware complexity grows exponentially
Solution Approach 1:
The patent segments the arbitration process into two distinct phases: a setup phase where the arbitration table is converted into count values, and an execution phase where simple countdown logic arbitrates requests. This segmentation transforms the complex single-phase arbitration table lookup into a two-phase process with simplified hardware requirements in the critical execution path.
Solution Approach 2:
The patent performs preliminary action by pre-converting the arbitration table into count values during a setup phase before actual arbitration occurs. This pre-processing step transforms the complex arbitration table into a simpler format that can be efficiently used during runtime, eliminating the need for complex comparator hierarchies during the actual arbitration process.
2Adaptability or versatility
If a large arbitration table is used to handle multiple resource requests, then the resource distribution capability is improved, but the arbitration latency increases
Solution Approach 1:
By segmenting arbitration into setup and execution phases, the patent moves the complex table conversion work to the setup phase, allowing the execution phase to use simple countdown logic that operates in constant time regardless of the number of ports, thus reducing arbitration latency.
Solution Approach 2:
The preliminary conversion of the arbitration table into count values during setup phase eliminates the need for complex real-time comparisons during arbitration, reducing the time required to make arbitration decisions to simple counter decrements and comparisons.
3Adaptability or versatility
If more gates are added to implement a state machine for larger arbitration tables, then the resource distribution capability is improved, but the manufacturing cost and power consumption increase
Solution Approach 1:
The patent segments the arbitration functionality into a setup module that generates count values and an execution module that uses simple counters, replacing the need for extensive comparator logic and state machine gates with simpler, more manufacturable components.
Solution Approach 2:
The patent substitutes the mechanical/hardware-intensive state machine and comparator hierarchy with a software-configurable arbitration table converted into count values, replacing complex gate logic with simpler counter circuits that are easier and cheaper to manufacture.
Data Source
AI summary
A method and apparatus for conversion of an arbitration table into count values to control the distribution of resources have been described.