Speculative Error Prediction Circuitry for Pipeline Performance
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Solution Overview
Problem
Integrated circuits using speculative execution techniques face a significant performance penalty due to the need for error recovery operations, which is exacerbated in high-performance processors with deeply pipelined processing arrangements, as pipeline flushes require many processing cycles to refill.
Innovation Solution
Incorporating speculative error prediction circuitry to generate an early prediction of potential errors, allowing for a second error recovery operation with a lesser performance penalty, which can be triggered before the accurate determination by the speculative processing control circuitry, and includes stalling upstream pipeline stages to prevent further processing and correct errors without a full pipeline flush.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If speculative execution techniques are used to achieve lower operating voltages and higher operating speeds, then power consumption is reduced and performance is improved, but performance penalty occurs due to error recovery operations
Solution Approach 1:
The patent applies preliminary action by performing speculative error prediction before the actual error determination. The error prediction circuitry speculatively predicts errors at an earlier stage, allowing the system to take preventive actions before the error is confirmed, thereby reducing the performance penalty associated with error recovery operations.
Solution Approach 2:
The patent segments the error recovery process into two distinct operations: a first error recovery operation triggered by speculative error prediction, and a second error recovery operation triggered by accurate error determination. This segmentation allows the system to apply different recovery strategies based on the reliability of the error detection, reducing overall performance penalty.
2Reliability
If pipeline flushes are used for error recovery in deeply pipelined processing arrangements, then errors are corrected, but many processing cycles are lost due to pipeline refilling
Solution Approach 1:
The patent applies preliminary action by triggering a first error recovery operation based on speculative error prediction before the error is confirmed. This allows the system to take corrective actions earlier in the processing pipeline, potentially preventing the need for full pipeline flushes and reducing the number of processing cycles lost.
Solution Approach 2:
The patent implements dynamic error recovery by selecting between different recovery operations based on error prediction outcomes. The system dynamically adjusts its error handling strategy, using the first error recovery operation for predicted errors and the second operation for confirmed errors, thereby optimizing the balance between reliability and productivity.
Data Source
AI summary
An integrated circuit 2 is provided with a plurality of pipeline stages 10. These pipeline stages 10 have speculative processing control circuitry 12 which permits speculative processing in downstream pipeline stages and triggers a first error recovery operation (partial pipeline flushing) if such speculative processing is determined to be based upon an error. The pipeline stage 10 further includes speculative error detecting circuitry 14 which generates a prediction nc regarding whether or not the processing circuitry 18 will produce an error. This prediction is used to trigger a second error recovery operation (partial pipeline stall). This second error recovery operation has a lower performance penalty than the first error recovery operation.