Processor Capture Queue for Pipeline Hazard Management
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Solution Overview
Problem
Modern digital signal processors face challenges in executing instructions efficiently due to pipeline hazards and memory access issues, particularly in real-time data processing applications, where dependent instructions may require careful scheduling to avoid delays and ensure correct execution.
Innovation Solution
The implementation of a processor with an instruction execution pipeline that includes a capture queue to store and restore register states, allowing for the execution of higher priority instructions while ensuring that previous instructions' results are correctly available, thereby managing pipeline hazards and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an unprotected pipeline is used to increase processing speed, then instruction execution rate improves, but pipeline hazards cause incorrect data usage
Solution Approach 1:
The patent implements a capture queue that preemptively stores register states at specific capture points before pipeline hazards occur. This preliminary action allows the pipeline to continue executing instructions at high speed without waiting for hazard resolution, while the captured states ensure data correctness can be restored when needed.
Solution Approach 2:
The capture queue acts as an intermediary between the pipeline registers and the functional units. It intercepts and stores register states, allowing the pipeline to proceed without immediate concern for data dependencies, while providing a mechanism to retrieve correct states when hazards are detected.
2Productivity
If pipeline depth is increased to improve throughput, then processing efficiency improves, but hazard detection complexity increases
Solution Approach 1:
The patent divides the pipeline into segments with specific capture points inserted at strategic locations. Rather than implementing complex hazard detection throughout the entire deep pipeline, the capture points segment the pipeline into manageable sections, simplifying the detection and resolution logic at each segment.
Solution Approach 2:
The capture queue serves as an intermediary structure that simplifies hazard management in deep pipelines. Instead of complex inter-stage hazard detection logic, the capture queue provides a straightforward mechanism to store and restore states, reducing the overall complexity of hazard detection while maintaining deep pipeline throughput.
3Reliability
If capture points are inserted to manage hazards, then data correctness improves, but pipeline structure complexity increases
Solution Approach 1:
The patent merges the capture queue functionality with the existing pipeline register structure. Rather than adding completely separate hazard management hardware, the capture points are integrated into the pipeline stages, combining state capture with the natural pipeline flow and reducing overall structural complexity.
Solution Approach 2:
The capture queue is designed to serve multiple functions: it captures register states for hazard resolution, maintains pipeline timing, and provides restoration capability. This multi-functionality reduces the need for separate dedicated hazard management structures, simplifying the overall pipeline design while ensuring data correctness.
Data Source
AI summary
Techniques related to executing a plurality of instructions by a processor comprising receiving a first instruction for execution on an instruction execution pipeline, beginning execution of the first instruction, receiving one or more second instructions for execution on the instruction execution pipeline, the one or more second instructions associated with a higher priority task than the first instruction, storing a register state associated with the execution of the first instruction in one or more registers of a capture queue associated with the instruction execution pipeline, copying the register state from the capture queue to a memory, determining that the one or more second instructions have been executed, copying the register state from the memory to the one or more registers of the capture queue, and restoring the register state to the instruction execution pipeline from the capture queue.