In-Memory Trace Overlapping Frontend Backend Logout
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Solution Overview
Problem
In-memory trace (IMT) technologies face inefficiencies in processing throughput due to serialized data transfer methods, which can alter software behavior and result in invalid trace results when processor speed is drastically reduced, leading to prolonged trace record transfer times.
Innovation Solution
The method involves partitioning the instruction pipeline into frontend and backend groups, allowing for overlapping trace record transfers by performing frontend and backend logout operations concurrently, enabling the start of new instructions before backend logout completion and suppressing new trace record generation until logout is complete, thereby reducing total trace record transfer time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If serialized processing is used to ensure IMT data coherence, then data integrity is improved, but processing throughput is drastically reduced
Solution Approach 1:
The instruction pipeline is divided into multiple groups (e.g., frontend group and backend group), each capable of independent trace record collection and transfer. This segmentation allows parallel processing of trace records from different pipeline stages, maintaining data integrity through group-level serialization while improving overall throughput through inter-group parallelism.
Solution Approach 2:
Trace records are collected and buffered in each pipeline group before the logout operation. By preparing data in advance within each group, the system can perform coherent trace transfers without blocking instruction execution, thus maintaining both data integrity and processing throughput.
2Measurement precision
If processor speed is drastically reduced for in-memory trace mode, then trace collection accuracy is improved, but software behavior may be altered
Solution Approach 1:
By segmenting the pipeline into multiple groups that can operate in parallel, the system reduces the time each group needs to spend in slow-mode trace collection. This allows faster processing speeds that maintain software behavior integrity while still achieving accurate trace collection through the segmented approach.
Solution Approach 2:
The overlapped logout mechanism allows continuous instruction execution by enabling the next instruction to start before the current instruction's trace records are fully transferred. This continuity maintains processing speed and software behavior integrity while ensuring complete and accurate trace collection through the overlapping operation.
3Reliability
If trace record transfer is performed sequentially, then data coherence is ensured, but total transfer time is prolonged
Solution Approach 1:
Multiple sequential logout operations from different pipeline groups are merged into a single parallel operation. The frontend group and backend group can transfer their trace records simultaneously to the trace controller, reducing total transfer time while maintaining coherence through controlled parallel execution.
Solution Approach 2:
Each pipeline group completes its trace record collection and preparation before initiating the logout operation. This preliminary action ensures that when multiple groups transfer records in parallel, the data coherence is maintained because each group's records are ready and consistent, while the parallel transfer reduces total time.
Data Source
AI summary
A computer-implemented method includes assigning a first group of one or more units of an instruction pipeline of a processor as a frontend group and assigning a second group of the one or more units of the instruction pipeline of the processor as a backend group. A frontend logout is performed to transfer one or more trace records from the first group to a trace controller during an in-memory trace of an instruction. A backend logout is performed to transfer one or more trace records from the second group to the trace controller during the in-memory trace of the instruction. A next instruction is started in the first group of the instruction pipeline before the backend logout completes.