Ring Buffer Trace Data Collection via Timestamp Synchronization
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Solution Overview
Problem
Current software data-path implementations face challenges in minimizing CPU costs and ensuring compactness of trace data generation for efficient bug analysis and performance analysis, particularly in supporting high trace generation rates with limited computing resources.
Innovation Solution
A method involving a ring buffer in a first memory with multiple trace buffers, where trace data items are stored and retrieved based on timestamps, and then transferred to a second memory device, ensuring efficient storage and synchronization without the need for locks or validity bits, thus reducing CPU cycles and cache contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional locking mechanisms are used to protect trace buffer access, then data integrity is improved, but CPU overhead and device complexity increase
Solution Approach 1:
The patent extracts the synchronization responsibility from complex lock mechanisms and relocates it to simpler timestamp-based validation. The ring buffer removes the need for locks by using timestamps to indicate when data is ready for consumption, thereby maintaining data integrity while reducing device complexity.
Solution Approach 2:
The patent replaces the mechanical locking system with a timestamp-based validation mechanism. Instead of using locks to control access, the system uses timestamps to synchronize producer and consumer, eliminating the need for complex locking hardware and software while maintaining data integrity.
2Quantity of substance
If trace data is stored in compact format, then storage efficiency is improved, but data integrity and reliability may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-validating trace data integrity through timestamp generation at the point of production. The timestamp is generated when the trace data is written to the ring buffer, ensuring that the data is complete and valid before being transferred to the second memory device, thus maintaining data integrity while enabling compact storage.
3Productivity
If high trace generation rate is achieved, then productivity is improved, but CPU cost and resource consumption increase
Solution Approach 1:
The patent implements self-service by having the ring buffer automatically manage its own synchronization through timestamps. The producer generates timestamps automatically when writing trace data, and the consumer uses these timestamps to determine when data is ready, eliminating the need for CPU-intensive locking operations and reducing overall CPU cost while maintaining high productivity.
4Speed
If trace data is retrieved immediately from ring buffer, then speed is improved, but data integrity may be compromised due to concurrent access
Solution Approach 1:
The patent applies feedback by using timestamps as a synchronization mechanism. The producer generates a timestamp when the trace data is ready, and this timestamp is fed back to the consumer to indicate when the data can be safely retrieved. This feedback mechanism ensures data integrity while allowing fast retrieval without concurrent access conflicts.
Data Source
AI summary
A method is provided for collecting trace data items generated by a plurality of trace points, the method comprising: allocating a ring buffer in a first memory, the ring buffer including a plurality of trace buffers; when any of the trace points is executed, storing a trace data item generated by the trace point in one of the plurality of trace buffers that is identified by a given value of a ring pointer; retrieving the trace data item from the trace buffer based on at least one of: (i) a first timestamp that is generated when the trace data item is stored in the trace buffer, and (ii) a second timestamp indicating a time when the ring pointer was assigned the given value; and storing the retrieved trace data item in a second memory device.