Cache Element Quality Ranking and Dynamic Swap for CPU Repair
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Solution Overview
Problem
Cache memories in processors can develop persistent errors, leading to degraded CPU performance and requiring physical replacement, resulting in system downtime and inefficiency.
Innovation Solution
A method is introduced where each cache element is assigned a quality rank based on its error rate, and a non-allocated cache element with a better rank is swapped in to replace a faulty allocated one, allowing for continuous monitoring and repair without system reboot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical removal and replacement of faulty cache memory is performed, then reliability is improved, but loss of time increases
Solution Approach 1:
The cache memory is divided into multiple independent cache elements (e.g., 8-way set associative cache with 8 separate cache elements). This segmentation allows individual faulty elements to be replaced without replacing the entire cache memory, enabling continuous operation of the remaining elements and thus reducing system downtime while maintaining reliability.
Solution Approach 2:
The patent implements dynamic replacement of cache elements based on their operational status. The system monitors cache element performance and dynamically swaps faulty elements with healthy ones from a replacement pool, allowing the cache memory to adapt and maintain functionality without requiring physical removal and replacement of the entire cache assembly, thereby reducing downtime.
2Reliability
If physical removal and replacement of entire CPU module is performed, then reliability is improved, but loss of time increases
Solution Approach 1:
The cache memory within the CPU is segmented into multiple independent elements that can be individually managed. When a cache element fails, only that specific element needs replacement rather than the entire CPU module, significantly reducing the downtime and maintaining CPU operability while improving reliability.
Solution Approach 2:
The patent employs a replacement pool of healthy cache elements that can be recovered and reused. When a cache element fails, a healthy element from the replacement pool is swapped in, allowing the system to continue operating without replacing the entire CPU module, thus reducing loss of time while maintaining reliability.
3Reliability
If field personnel perform physical replacement, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service repair mechanism where the system automatically identifies faulty cache elements, selects replacement candidates from a pre-configured replacement pool, and executes the swap operation without requiring field personnel intervention. This automated approach reduces the complexity of the repair process while maintaining reliability, as the system manages its own maintenance needs through built-in monitoring and replacement logic.
Solution Approach 2:
The system continuously monitors cache element performance and provides feedback on their operational status. This feedback mechanism enables automatic identification of faulty elements and triggers the replacement process, eliminating the need for manual inspection by field personnel and reducing the complexity of the repair process while ensuring reliability through data-driven decision-making.
Data Source
AI summary
In one embodiment, a cache element allocation method is provided. Each cache element on a CPU is assigned a quality rank based on the error rate of the cache element. If an allocated cache element is deemed to be faulty, the quality rank of the faulty allocated cache element is compared with the quality rank of the non-allocated cache elements. If a non-allocated cache element has a lower quality rank than the allocated cache element, the non-allocated cache element is swapped in for the allocated cache element.