Cache Line Lifetime Hints for Bit-Accurate Trace Logging
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Solution Overview
Problem
Existing diagnostic tools struggle to efficiently record and analyze execution traces due to the large size of replayable execution traces, which grow rapidly even when capturing short periods of execution, making it difficult to identify and analyze undesired software behaviors.
Innovation Solution
Logging cache line lifetime hints when recording execution traces, which enables the identification of time-windows during which a cache line value is valid for trace replay, allowing for more efficient trace analysis and resource conservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If replayable execution traces are recorded by capturing cache influxes, then bit-accurate historic execution trace data is obtained enabling virtual replay, but the trace files grow very large in size in memory and/or on disk
Solution Approach 1:
The patent extracts and records only the essential information needed for replay - specifically cache line lifetime hints (start and end addresses) - rather than capturing complete cache influx data. This selective extraction maintains bit-accuracy for critical replay information while dramatically reducing the volume of trace data stored in memory and on disk.
2Reliability
If comprehensive execution trace data is captured, then complete replay capability is achieved, but trace analysis becomes difficult due to large data volume
Solution Approach 1:
The patent extracts only the critical lifetime hint information (start and end addresses of cache lines) needed for effective trace analysis and replay. By removing unnecessary detailed cache data while retaining the essential temporal boundaries, the system maintains reliable replay capability while making trace analysis significantly more manageable and efficient.
Data Source
AI summary
Logging cache line lifetime hints when recording an execution trace. A microprocessor detects occurrence of a first cache event that initiates a lifetime of a cache line within a memory cache, and initiates logging first trace information indicating a beginning of the lifetime of the cache line within the memory cache. Subsequently, the microprocessor detects occurrence of a second cache event that ends the lifetime of the cache line within the memory cache. Based on detecting the second cache event, the microprocessor initiates logging second trace information indicating an ending of the lifetime of the cache line within the memory cache.