Adaptive Processor Pipeline Bypass for Hazard Latency Reduction
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Solution Overview
Problem
Pipelining in processing systems increases instruction execution rate but also introduces significant latency due to hazards like data dependencies and control flow changes, leading to pipeline stalls that degrade system performance.
Innovation Solution
A processor with adaptive pipeline control logic that selectively configures the pipeline length based on the type of instruction being executed, using reduced length for instructions that cause hazards and full length for others, and incorporates latency reduction logic to execute certain instructions in fewer stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pipelining is used to increase instruction execution rate, then productivity is improved, but loss of time increases due to pipeline latency
Solution Approach 1:
The pipeline configuration is made dynamic and adaptive rather than static. The pipeline control logic dynamically adjusts the number of pipeline stages based on the type of instruction being executed. Different instruction types (e.g., arithmetic, logical, memory access, branch instructions) are routed through different numbers of pipeline stages, allowing the system to optimize between throughput and latency on a per-instruction basis.
Solution Approach 2:
The patent changes the parameter of pipeline depth dynamically. Instead of using a fixed number of pipeline stages for all instructions, the system varies the effective pipeline depth parameter based on instruction characteristics. Simple instructions use fewer stages to reduce latency, while complex instructions utilize the full pipeline depth to maintain throughput capability.
2Adaptability or versatility
If pipeline stages are increased to handle more instruction types, then adaptability is improved, but device complexity increases
Solution Approach 1:
The pipeline is segmented into multiple functional stages, each capable of handling specific instruction types. The pipeline control logic segments the instruction stream and routes different instruction types through appropriate numbers of stages. This segmentation allows the system to handle diverse instruction types while maintaining a manageable structure where each stage has a defined, simplified function.
Solution Approach 2:
The pipeline stages are designed with multi-functionality to handle various instruction types. Rather than having dedicated hardware for each instruction type, the same pipeline infrastructure is universally applied to different instructions by dynamically configuring which stages are active. This universal approach reduces overall device complexity while maintaining high adaptability.
Data Source
AI summary
A system and method for reducing pipeline latency. In one embodiment, a processing system includes a processing pipeline. The processing pipeline includes a plurality of processing stages. Each stage is configured to further processing provided by a previous stage. A first of the stages is configured to perform a first function in a pipeline cycle. A second of the stages is disposed downstream of the first of the stages, and is configured to perform, in a pipeline cycle, a second function that is different from the first function. The first of the stages is further configured to selectably perform the first function and the second function in a pipeline cycle, and bypass the second of the stages.