Distributed Loop Controller Architecture for Multi-threading
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Solution Overview
Problem
Current microcomputer architectures for embedded systems face challenges in reducing power consumption, particularly in the instruction memory hierarchy and register files, which are major energy bottlenecks, and struggle to efficiently execute multiple incompatible loops in parallel, limiting performance and energy efficiency.
Innovation Solution
A virtually multi-threaded distributed instruction memory hierarchy is proposed, with clustered loop buffers and local controllers that support both single-threaded and multi-threaded operations, enabling the execution of multiple incompatible loops in parallel while minimizing hardware overhead and optimizing data communication through register file-level synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If distributed loop buffers with single loop controller are used, then instruction memory energy is reduced, but only one thread of control is supported
Solution Approach 1:
The single loop controller is segmented into multiple independent loop controllers (first loop controller and second loop controller), each capable of independently controlling a distributed loop buffer. This segmentation enables multi-threaded operation while maintaining the energy efficiency of distributed buffer architecture.
Solution Approach 2:
The loop controllers are designed with multi-functionality to support both single-threaded and multi-threaded operations. The same distributed loop buffer infrastructure can serve multiple threads when multiple controllers are present, providing adaptability without requiring separate hardware for different operating modes.
2Adaptability or versatility
If multiple loop controllers are added to support multi-threading, then thread of control support is improved, but device complexity increases
Solution Approach 1:
The control architecture is segmented into independent loop controller units, where each controller manages a specific thread. This modular segmentation allows the system to scale with the number of threads while maintaining manageable complexity through repetition of standardized controller modules.
Solution Approach 2:
Instead of having a single complex controller manage multiple threads, the approach inverts the architecture by having multiple simple controllers each managing one thread. This inversion simplifies individual controller design while achieving multi-threading capability at the system level.
3Productivity
If loop fusion is applied to execute multiple threads in parallel, then productivity is improved, but control overhead increases due to incompatible loops
Solution Approach 1:
The processor architecture is segmented into multiple independent processing clusters, each with its own loop controller and functional units. This segmentation allows incompatible loops to be executed in parallel without requiring complex fusion logic, as each cluster independently manages its own loop execution.
Solution Approach 2:
The distributed loop controllers act as intermediaries between the instruction memory hierarchy and the processing units. Each controller independently manages loop execution and data flow, eliminating the need for complex control logic to coordinate incompatible loops across shared resources.
4Adaptability or versatility
If context switching is used to execute multiple loops, then adaptability is improved, but loss of time increases due to switching overhead
Solution Approach 1:
Multiple loops execute continuously in parallel across different processing clusters without interruption for context switching. Each loop maintains its own execution state in its dedicated cluster, eliminating the need to save and restore context and ensuring continuous useful action across all threads.
Solution Approach 2:
The processing architecture is segmented into isolated clusters, each maintaining independent execution state. This segmentation eliminates the need for context switching by providing dedicated resources for each thread, allowing loops to run continuously without time loss from switching operations.
Data Source
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AI summary
The present invention proposes a virtually multi-threaded distributed instruction memory hierarchy that can support the execution of multiple incompatible loops in parallel. In addition to regular loops, irregular loops with conditional constructs and nested loops can be mapped. In the architecture in accordance with embodiments of the present invention, the loop buffers are clustered, each loop buffer having its own local controller, and each local controller is responsible for indexing and regulating accesses to its loop buffer.