Butterfly Network LUT Read Reordering for Lower Memory Latency
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Solution Overview
Problem
Modern digital signal processors face challenges with increasing workloads, memory system latency, unreliable memories and registers, routing congestion, and wire speed disparities, which impact the efficiency of complex algorithms and systems on a chip.
Innovation Solution
A digital data processor incorporates a multi-stage butterfly network that reorders lookup table data based on control signals and writes it to a destination register in response to a lookup table read instruction, optimizing data processing through a dual scalar/vector datapath architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored in memory for lookup table operations, then data availability is improved, but memory system latency increases
Solution Approach 1:
The patent divides the lookup table data into multiple segments that can be processed in parallel through the butterfly network. By segmenting the data retrieval operation into concurrent paths, the system maintains data availability while reducing the effective latency through parallel access patterns.
Solution Approach 2:
The patent performs preliminary reordering of lookup table data through the butterfly network before the actual data is needed for processing. By pre-organizing data in the desired sequence using control signals, the system eliminates latency during critical data retrieval operations.
2Productivity
If more data routing paths are added to handle increasing workloads, then data processing capacity is improved, but routing congestion increases
Solution Approach 1:
The patent implements dynamic data routing through the butterfly network where control signals adaptively direct data flow based on current processing needs. This dynamic routing allows the system to handle increasing workloads efficiently without creating static congestion patterns, as paths are optimized in real-time.
Solution Approach 2:
The butterfly network structure serves multiple functions: it reorders data, routes information between processing units, and manages lookup table operations. This multi-functionality allows a single routing structure to handle diverse workload types without requiring separate dedicated paths for each function, reducing overall routing congestion.
3Productivity
If lookup table data is reordered based on control signals, then data processing efficiency is improved, but device complexity increases
Solution Approach 1:
The patent introduces control signals as an intermediary mechanism that manages the reordering process. These control signals act as a mediator between the butterfly network and the lookup table data, directing reordering operations without requiring complex hardwired logic. This soft-controlled approach improves processing efficiency while keeping the reordering mechanism manageable.
Data Source
AI summary
A digital data processor includes a multi-stage butterfly network, which is configured to, in response to a look up table read instruction, receive look up table data from an intermediate register, reorder the look up table data based on control signals comprising look up table configuration register data, and write the reordered look up table data to a destination register specified by the look up table read instruction.