Graphics Processor Buffer Checker for Fault Detection
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Solution Overview
Problem
Existing graphics processing systems for safety-critical applications, such as advanced driver-assistance systems and autonomous vehicles, face challenges in meeting stringent safety standards due to increased area and power consumption associated with dual lockstep processors.
Innovation Solution
A graphics processing system that includes one or more processing units, a check unit for forming signatures characteristic of processed outputs, and a fault detection unit for comparing these signatures. The system processes each task twice, generating first and second processed outputs, and raises a fault signal if the signatures do not match.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual lockstep processors are used for fault detection, then reliability is improved, but area and power consumption increase
Solution Approach 1:
The patent uses a buffer to store a copy of previously processed task output and compares it with the current processing result. This copying approach enables fault detection without requiring duplicate processing units, thereby reducing chip area while maintaining reliability through result verification
Solution Approach 2:
The buffer pre-stores the output from previous task processing before new processing occurs. This preliminary storage allows immediate comparison between old and new results, enabling rapid fault detection without waiting for additional processing cycles
2Reliability
If dual lockstep processors are used for fault detection, then reliability is improved, but power consumption increases
Solution Approach 1:
Instead of running duplicate processing units that would consume double the power, the patent copies only the output data to a buffer for comparison. This selective copying approach maintains fault detection capability while significantly reducing power consumption by avoiding redundant computation
Solution Approach 2:
The patent extracts only the essential comparison function from the dual lockstep architecture, separating the fault detection logic from the main processing units. This extraction allows using a single processor with buffer comparison, eliminating the power overhead of maintaining two active processing cores
3Reliability
If systematic errors are completely excluded through rigorous development, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where processing results are stored in a buffer and continuously compared against previous results. This automated feedback loop detects systematic errors at runtime without requiring extensive manual code auditing or complex development processes, thereby improving reliability while keeping manufacturing feasible
Data Source
AI summary
A graphics processing system with a data store includes processing units for processing tasks. A check unit forms a signature which is characteristic of an output from processing a task on a processing unit, and a fault detection unit compares signatures formed at the check unit. Each task is processed first and second times at the processing units to generate first and second processed outputs. The graphics processing system write outs the first processed output to the data store, reads back the first processed output from the data store and forms at the check unit a first signature characteristic of the first processed output as read back from the data store; forms at the check unit a second signature characteristic of the second processed output, compares the first and second signatures at the fault detection unit, and raises a fault signal if the signatures do not match.