Hardware Timestamp Synchronization in Multi-Node Systems
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Solution Overview
Problem
Multi-node systems face challenges in reconciling events timestamped in different time domains, particularly in low-latency hardware timestamping scenarios, where precise synchronization is crucial for accurate data alignment and processing.
Innovation Solution
The use of hardware timestamping units (TSU) within digital signal processors (DSPs) of systems-on-chip (SoCs) to record local timestamps of events, with a bus sharing these values to compute deltas and adjust timestamps accordingly, enabling synchronization across nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware timestamping is implemented in multi-node systems, then synchronization precision is improved, but system complexity increases
Solution Approach 1:
The system divides timestamp synchronization into separate modules: hardware timestamping units in each node, a central synchronization processor, and software reconciliation components. This segmentation allows each component to focus on specific tasks, improving precision while managing complexity through modular architecture.
Solution Approach 2:
A centralized synchronization processor acts as an intermediary between distributed hardware timestamping units. It collects timestamps from multiple nodes, performs coordination, and distributes corrected timestamps back to nodes, thereby achieving precise synchronization without requiring direct complex interactions between all nodes.
2Manufacturing precision
If multiple nodes are synchronized using hardware timestamps, then data alignment accuracy is improved, but processing overhead increases
Solution Approach 1:
The hardware timestamping units operate in advance to capture precise timestamps at the time of event occurrence, before any processing or data transfer. This preliminary timing action ensures that accurate alignment information is already available when data needs to be processed, reducing subsequent processing overhead.
Solution Approach 2:
Each node's hardware timestamping unit autonomously records local timestamps without requiring constant intervention from the central processor. The nodes self-manage their timing operations, and the central processor only performs coordination and reconciliation, thereby reducing overall processing overhead while maintaining accuracy.
3Measurement precision
If timestamps are reconciled across different time domains, then synchronization precision is improved, but latency increases
Solution Approach 1:
The system replaces complex software-based time synchronization mechanisms with hardware timestamping units that directly capture precise timing information. This substitution of mechanical/software processes with hardware-based timing enables precise timestamp collection without the latency introduced by multiple software processing steps.
Solution Approach 2:
The hardware timestamping units continuously record timestamps as events occur, maintaining continuous timing information without interruption. This continuous operation ensures that timestamp reconciliation can proceed with minimal delay, as the data is already prepared and waiting, rather than requiring periodic sampling or batch processing.
Data Source
AI summary
Techniques are described for reconciling events timestamped in different time domains in multi-node systems supporting low-latency hardware timestamping. First and second nodes having independent time bases are synchronized by the first node generating an event that is received effectively simultaneously at the first and second nodes, the first and second nodes recording a timestamp of receipt of the event, the first node asynchronously querying the second node for its timestamp of receipt of the event and comparing its timestamp of receipt of the event with the timestamp of receipt of the event by the second node, and the first node using a difference in the timestamps of receipt of the event by the first and second nodes to align the time bases of the first and second nodes. The nodes may include hardware timestamping functionality or use an external component (e.g., field programmable gate array) to provide the timestamping functionality.