Processor Module Lockstep Recovery via Firmware Idling
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Solution Overview
Problem
Existing systems face challenges in responding to detected loss of lockstep in processor modules without crashing the entire system, especially in large multi-processor systems where frequent cosmic events lead to increased system crashes, and current solutions require significant OS updates and are not widely supported.
Innovation Solution
System firmware instructs the operating system to idle a processor module upon detecting loss of lockstep, allowing the firmware to regain control and attempt recovery without halting the system, using ACPI methods to manage processor state and reestablish lockstep protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system crashes the entire system upon detecting loss of lockstep in a processor module, then system reliability is improved by preventing corrupt data propagation, but system availability deteriorates due to complete system halt
Solution Approach 1:
The system segments the multi-processor system into independent processor modules, allowing the firmware to identify and isolate only the specific processor module experiencing loss of lockstep. This segmentation enables selective idling of the affected processor while maintaining operation of other processors, thus preventing complete system crash while ensuring reliability by containing the error locally.
Solution Approach 2:
The firmware extracts the affected processor module from active service by idling it, removing the potentially corrupt processor from the system's operational pool. This extraction allows the system to continue operating with remaining healthy processors while the problematic processor is taken out for recovery or failure handling, balancing reliability and availability.
2Reliability
If the operating system implements processor-specific updates to handle loss of lockstep recovery, then recovery capability is improved, but system adaptability deteriorates due to limited OS support
Solution Approach 1:
The firmware acts as an intermediary layer between the hardware (processor modules) and the operating system. It implements the loss of lockstep detection and recovery logic in firmware rather than requiring OS-level changes. This intermediary approach allows the firmware to manage processor recovery independently, maintaining broad OS compatibility while providing robust recovery capabilities through firmware-based error handling and processor idling mechanisms.
3Productivity
If the system continues operating without idling the processor after detecting loss of lockstep, then system productivity is maintained, but data corruption risk increases due to continued use of potentially corrupt processor
Solution Approach 1:
The firmware takes preliminary action by idling the processor module immediately upon detecting loss of lockstep, before any corrupt data can be processed or propagated. This preemptive idling prevents potential data corruption while maintaining system productivity by allowing other processors to continue operating. The firmware also attempts recovery operations while the processor is idled, preparing it for potential reinstatement without compromising data integrity.
Data Source
AI summary
According to one embodiment, a method comprises system firmware instructing a system's operating system to idle a processor, and responsive to the instructing, the operating system idling the processor and returning control over the processor to the system firmware. According to one embodiment, a method comprises detecting loss of lockstep (LOL) for a processor module in a system, and responsive to the detecting LOL for the processor module, system firmware instructing an operating system to idle the processor module.