Timestamp Correction Circuit for Network Interface Jitter
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Solution Overview
Problem
Existing timestamping technologies in network interfaces face challenges in achieving accurate event timestamping due to software entities in virtualized environments and high network speeds, leading to uncertainty and jitter in timestamp generation.
Innovation Solution
A processing apparatus with timestamping units and correction processing circuitry that uses AI models to compute corrections based on hardware state parameters, such as queue occupancy and link speed, to adjust timestamps for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If timestamp is generated close to the event in the packet processing pipeline, then timestamp generation speed is improved, but timestamp accuracy deteriorates due to hardware optimizations, buffering, and arbitration delays causing jitter
Solution Approach 1:
The patent stores multiple timestamp values at different pipeline stages (ingress, egress, and intermediate stages) before final selection. This preliminary capture of multiple time points allows the system to later select the most appropriate timestamp that best represents the actual event time, compensating for the jitter introduced by hardware optimizations and buffering.
Solution Approach 2:
The system implements feedback by monitoring pipeline delay variations and using this information to select or adjust timestamps. The timestamp correction processing circuitry analyzes the stored timestamps from different stages and selects the one that most accurately reflects the event time, effectively using feedback from the pipeline state to improve accuracy.
2Adaptability or versatility
If multiple software entities are involved in virtualized environments, then system versatility is improved, but timestamp accuracy deteriorates due to difficulty in generating precise event timestamps
Solution Approach 1:
The patent segments the timestamping function into multiple independent hardware components within the NIC, each capable of generating timestamps at different pipeline stages. This segmentation allows the system to maintain versatility for multiple software entities while achieving high accuracy through hardware-based timestamping that is independent of software virtualization overhead.
Solution Approach 2:
The patent introduces an intermediary timestamp correction mechanism that acts as a mediator between the multiple software entities and the hardware timestamping resources. This intermediary layer manages and selects from multiple captured timestamps, providing accurate timing information to virtualized software entities without requiring direct software control over the hardware timestamping process.
3Productivity
If high network speeds are used (25 Gbps and above), then data transmission productivity is improved, but timestamp accuracy deteriorates due to processing delays and jitter
Solution Approach 1:
At high network speeds, the patent captures multiple timestamps in advance at different processing stages before the packet completes its journey through the pipeline. This preliminary capture ensures that even with fast processing, the system has multiple time reference points available to accurately determine when the event of interest actually occurred, compensating for the reduced time margins at higher speeds.
Solution Approach 2:
The system dynamically adapts its timestamp selection strategy based on the actual pipeline conditions and packet processing path. At high speeds, the timestamp correction circuitry selectively chooses from pre-captured timestamps based on real-time analysis of which timestamp best represents the event time, allowing the system to maintain accuracy despite the dynamic and varying delays inherent in high-speed processing.
Data Source
AI summary
In one embodiment, a processing apparatus includes processing circuitry to process an event, a timestamping unit to generate a timestamp for the event, at least one register to store at least one parameter describing a hardware state of the processing circuitry, and timestamp correction processing circuitry to compute a time value as a correction to the generated timestamp responsively to the at least one parameter.