L2 Cache ECC Conversion for Non-Correctable Error Handling
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Solution Overview
Problem
Existing memory systems face challenges in maintaining adequate functional safety and efficiency in the presence of non-correctable errors, particularly in multi-level cache systems with varying ECC protection levels, leading to performance degradation and increased power consumption.
Innovation Solution
Implementing an L2 controller that transforms ECC protection from SECDED to SED and corrects errors, while enabling early transaction termination upon detecting non-correctable errors, thereby reducing latency and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SECDED ECC protection is implemented in the memory system, then error correction capability is improved, but power consumption and access time increase
Solution Approach 1:
The patent applies different ECC protection levels to different memory locations based on their importance. Critical data in the L2 cache receives full SECDED protection, while less critical data in lower-level caches uses simpler SED protection. This localized differentiation allows the system to maintain high reliability for important data while reducing overall power consumption and access time.
Solution Approach 2:
The system dynamically selects ECC protection levels based on data characteristics, access patterns, and error severity. When non-correctable errors are detected, the system adapts by terminating transactions early or switching to alternative error handling mechanisms, rather than always applying maximum ECC protection, thereby optimizing the balance between reliability and performance.
2Reliability
If SECDED ECC protection is implemented, then error correction capability is improved, but access speed deteriorates
Solution Approach 1:
The patent implements heterogeneous ECC protection where different cache levels use different ECC schemes. The L2 cache uses SECDED for critical data, while lower-level caches use simpler protection. This allows fast access for non-critical data while maintaining strong error correction for important data, resolving the speed-reliability tradeoff.
Solution Approach 2:
The system performs ECC checking and error correction in parallel with normal memory access operations. By preparing correction codes and validating data simultaneously during read/write operations, the system minimizes the impact of ECC processing on access speed while maintaining robust error correction capability.
3Productivity
If early transaction termination is implemented for non-correctable errors, then productivity is improved, but reliability may worsen
Solution Approach 1:
The patent introduces an intermediary error handling layer between the memory subsystem and the processor. When non-correctable errors are detected, this intermediary layer manages transaction termination, error logging, and system state preservation. This mediator ensures that early termination improves performance while maintaining system reliability through proper error management and data integrity protocols.
Data Source
AI summary
An example system includes a memory and a controller. In operation, the controller calculates a first type of error correcting code (ECC) protection for a portion of data; stores the portion of data and the first type of ECC protection associated with the portion of data in the memory; receives a request, directed to the portion of data, from a requestor that implements a second type of ECC protection; transforms the protection for the portion of data from the first type of ECC protection to the second type of ECC protection; and sends to the requestor a response based on the transformed protection.