Fractured ALU Pipeline for Parallel CGRA Address Generation
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Solution Overview
Problem
Coarse-grained reconfigurable architectures (CGRAs) face challenges in maximizing compute unit utilization due to insufficient data bandwidth for high compute throughput, particularly in generating memory addresses at high throughput for arbitrary memory access patterns, which is critical for pipelined dataflow execution.
Innovation Solution
The physical arithmetic logic unit (ALU) pipeline is fractured into multiple pipeline segments, allowing concurrent allocation to multiple access threads, with each segment operating independently and being dynamically managed to generate memory addresses for multiple threads, utilizing a compiler to optimize address sequence generation based on memory access patterns and ALU capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single physical ALU pipeline is used, then device complexity is reduced, but address generation throughput is insufficient for multiple concurrent access threads
Solution Approach 1:
The physical ALU pipeline is divided into multiple virtual pipeline segments that can be dynamically allocated to different access threads. Each segment can independently generate address sequences for specific memory access patterns, enabling concurrent address generation for multiple threads while sharing the same physical hardware resources.
Solution Approach 2:
The pipeline segments are dynamically configurable and can be reallocated based on runtime requirements. The system can adjust the number, size, and configuration of pipeline segments to match the demands of different access threads, providing flexible throughput optimization without permanent hardware duplication.
2Adaptability or versatility
If the ALU pipeline is fractured into multiple segments, then concurrent address generation for multiple threads is enabled, but control and management complexity increases
Solution Approach 1:
The fractured ALU pipeline segments are designed to be universal and can serve multiple access threads with different memory access patterns. Each segment can be configured to handle various address generation tasks, making the system adaptable to diverse computational workloads without requiring dedicated hardware for each thread type.
Solution Approach 2:
A compiler intermediary is introduced to manage the complexity of pipeline segmentation. The compiler automatically analyzes memory access patterns, determines optimal pipeline segment configurations, and generates appropriate control code, shielding users from the underlying complexity while enabling efficient multi-thread support.
3Productivity
If pipeline segments are dynamically allocated, then compute unit utilization is maximized, but address sequence generation complexity increases
Solution Approach 1:
The compiler performs preliminary analysis of memory access patterns during the compilation phase, determining optimal pipeline segment allocations before runtime. This advance planning enables efficient compute unit utilization during execution without requiring complex real-time decision-making, as the segmentation strategy is pre-computed based on static program analysis.
Solution Approach 2:
The system incorporates feedback mechanisms where the compiler monitors actual pipeline performance and utilization, adjusting address sequence generation strategies accordingly. This feedback loop enables dynamic optimization of compute unit utilization while managing complexity through data-driven decisions rather than static configurations.
Data Source
AI summary
A fracturable data path of a configurable unit in an array of configurable units of a coarse-grained reconfigurable processor is disclosed. The fracturable data generates a plurality of independent address sequences. The plurality of independent address sequences includes a first address sequence generated using a first address calculation and a second address sequence generated using a second address calculation. The fracturable data path comprises a plurality of pipelined computation stages.