Packet Time Stamping by Polling in Virtualized Cloud Environments
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Solution Overview
Problem
In virtualized and cloud environments, the lack of access to dedicated hardware for time stamping network packets poses a challenge, making it difficult to achieve the high accuracy and precision typically associated with hardware-based solutions.
Innovation Solution
A method and system for time stamping packets in virtualized and cloud environments that utilizes polling and interrupt-based packet reception to identify packets at multiple points in time, distributing timestamps within a time span, without requiring specialized hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware-based time stamping is used, then time stamping accuracy and precision are improved, but device complexity and hardware requirements increase
Solution Approach 1:
The patent creates a virtual copy of hardware time stamping functionality through software. By using polling to capture packet arrival times and calculating timestamps based on polling intervals and packet positions in the queue, the system replicates hardware time stamping accuracy without requiring dedicated hardware components. This allows virtualized environments to achieve precise time stamping while maintaining software-only architecture.
2Productivity
If polling is used to read NIC buffer, then processing overhead is reduced at high packet rates, but timestamp accuracy may deteriorate due to less frequent polling
Solution Approach 1:
The patent performs preliminary actions by recording the polling time and calculating the time span before packets are actually processed. By pre-calculating the timestamp based on when the polling occurred rather than when packets are individually processed, the system captures accurate arrival times while maintaining efficient batch processing. This preliminary timestamp assignment eliminates the need for per-packet timing measurements during high-speed processing.
Solution Approach 2:
The patent changes the parameter of when the timestamp is recorded from packet processing time to polling time. By shifting the timestamp reference point to the polling event rather than the individual packet handling event, the system achieves both high processing efficiency and accurate timing. The timestamp accuracy is determined by the polling interval rather than the packet processing interval, decoupling these two parameters.
3Loss of time
If interrupt-based packet reception is used, then response time to packet arrival is improved, but processing overhead increases at high packet rates
Solution Approach 1:
The patent implements periodic polling of the NIC buffer at fixed intervals rather than using interrupt-driven reception. This periodic action converts the irregular interrupt-based processing into a regular, predictable polling rhythm. By doing so, the system eliminates interrupt overhead while maintaining acceptable response times, as the polling interval can be tuned to balance between responsiveness and processing efficiency.
Data Source
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AI summary
A method and system for time stamping of packet data is described. Advantageous aspects of how time stamping of packet data can be achieved in both virtualized and cloud environments are detailed.