Deterministic Replay of Computing Environments via I/O Stream Recording
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Solution Overview
Problem
The non-deterministic nature of I/O operations in computing environments makes it difficult to precisely replay the execution of processor instructions, hindering debugging and performance analysis, as the same input and instructions may not produce the same results due to unpredictable I/O behavior.
Innovation Solution
A computing device and method that create a stream of memory, processor, and I/O data to allow deterministic replay of a system's execution from a previous state, using snapshot data, memory data, and I/O data to revert the system to a previous point in time and re-execute processes predictably.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If I/O operations are performed in a computing environment, then the system can interact with external devices and complete practical tasks, but the non-deterministic nature of I/O operations prevents precise replay of processor execution
Solution Approach 1:
The patent applies preliminary action by recording I/O operations, interrupt requests, and processor states in advance during normal execution. This pre-recording of data enables deterministic replay later, as the system has already captured all necessary information about I/O interactions before they need to be re-executed for debugging or analysis purposes.
Solution Approach 2:
The patent creates a copy of the execution environment by recording processor states, I/O operations, and interrupt requests separately from the original execution. This copying mechanism allows the system to reconstruct and replay the exact execution sequence without altering the original non-deterministic I/O behavior, enabling precise debugging while maintaining normal I/O functionality.
2Ease of repair
If developers attempt to debug application failures by re-running software, then they can investigate errors, but the non-deterministic I/O operations cause different execution paths and prevent precise error reproduction
Solution Approach 1:
The patent implements feedback by recording the actual I/O operations and interrupt requests that occurred during execution, then using this recorded information to control subsequent replay executions. This feedback loop ensures that debugging sessions reproduce the exact same execution path as the original failure, allowing developers to reliably observe and fix errors without being affected by I/O non-determinism.
Solution Approach 2:
The patent prepares debugging conditions in advance by recording all I/O operations, interrupt requests, and processor states during normal execution. This preliminary data collection enables deterministic replay during debugging, ensuring that the same execution path is reproduced without requiring developers to manually control or predict I/O behavior.
3Reliability
If the system records detailed I/O data for deterministic replay, then execution can be precisely re-executed, but the data storage requirements and processing overhead increase
Solution Approach 1:
The patent segments the execution data into distinct categories: processor states, I/O operations, and interrupt requests. This segmentation allows the system to record only the specific data elements necessary for deterministic replay in each category, avoiding redundant storage and enabling efficient processing during replay while maintaining complete accuracy for reproduction.
Solution Approach 2:
The patent extracts only the essential information needed for deterministic replay from the overall execution process. By identifying and recording specifically processor states, I/O operations, and interrupt requests—while ignoring unnecessary data—the system achieves accurate deterministic replay with minimized data storage requirements and processing overhead.
Data Source
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AI summary
A first computing device is provided for rolling back a computing environment. The computing device includes processors configured to acquire a stream containing entries including snapshot entries, memory entries, and input/output entries wherein each entry includes information and is associated with a timestamp. The processors are further configured to receive a snapshot entry associated with a first timestamp, revert to a memory state using information provided in at least one memory entry associated with a timestamp after the first timestamp, and re-execute a previously executed process, wherein the re-execution of the process is started using the first timestamp, information from the received snapshot entry, and information for input/output operations corresponding to the input/output entries associated with timestamps after the first timestamp.