Speculative Execution for Reliable Processor Error Detection

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Solution Overview

Problem

Traditional methods for ensuring execution reliability in electronic systems are costly and performance-detrimental, often requiring duplicate hardware or software that doubles execution time and resource consumption.

Innovation Solution

A system and method that uses speculative execution to duplicate program instructions, performing fault checking by executing multiple sets of operations in parallel and comparing results, with error mitigation through rollback to a known valid state if mismatches occur, allowing for reliable execution without significant performance impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional duplicate hardware or software systems are used to ensure reliability, then reliability is improved, but device complexity and cost increase significantly

Engineering Contradiction:

Improveexecution reliabilityVSAvoidhardware duplication

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates functional copies of instruction execution paths through speculative execution. Multiple speculative execution paths are generated from the same instruction stream, allowing reliability checking without duplicating physical hardware. The comparison logic detects discrepancies between these speculative paths to identify errors.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces physical hardware duplication with a software-based speculative execution mechanism. Instead of using separate physical processors or hardware redundant systems, the invention uses logical duplication through instruction speculation and comparison, substituting mechanical redundancy with computational redundancy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If traditional duplicate software systems are used to ensure reliability, then reliability is improved, but execution time increases due to sequential processing

Engineering Contradiction:

Improveexecution reliabilityVSAvoidexecution time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary speculative execution of instructions along multiple possible paths before knowing which path is correct. By executing instructions speculatively in advance and then validating results through comparison, the system identifies errors early without requiring sequential re-execution of entire instruction streams.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous execution flow by performing speculative execution alongside normal instruction processing. The comparison operation occurs continuously as instructions are executed, allowing error detection without interrupting the overall execution stream or requiring sequential validation steps.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If traditional duplicate hardware systems are used to ensure reliability, then reliability is improved, but resource consumption doubles

Engineering Contradiction:

Improveexecution reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent makes the same physical hardware resources serve multiple functions simultaneously. The execution units perform both normal instruction execution and speculative execution using the same physical components. The comparison logic reuses existing data paths and execution resources to validate results, avoiding the need for dedicated redundant hardware that would consume additional energy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If fault checking operations are performed to enhance reliability, then reliability is improved, but performance is adversely impacted

Engineering Contradiction:

Improveexecution reliabilityVSAvoidsystem performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent merges the fault checking function with the normal instruction execution flow. The speculative execution paths are generated and executed as part of the standard instruction processing pipeline, and the comparison operation is integrated into the existing execution architecture. This merging allows reliability checking to occur without adding separate performance-critical validation stages.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10289469B2Reliability enhancement utilizing speculative execution systems and methods

Publication Date: 2019.05.14 NVIDIA CORP

AI summary

Systems and methods for enhancing reliability are presented. In one embodiment, a system comprises a processor configured to execute program instructions and contemporaneously perform reliability enhancement operations (e.g., fault checking, error mitigation, etc.) incident to executing the program instructions. The fault checking can include: identifying functionality of a particular portion of the program instructions; speculatively executing multiple sets of operations contemporaneously; and comparing execution results from the multiple sets of operations. The multiple sets of operations are functional duplicates of the particular portion of the program instructions. If the execution results have a matching value, then the value can be made architecturally visible. If the execution results do not have a matching value, the system can be put in a safe mode. An error mitigation operation can be performed can include a corrective procedure. The corrective procedure can include rollback to a known valid state.