Virtual Clock Switch for VM Time Synchronization
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Solution Overview
Problem
In computer systems, especially in virtual environments, accurate time synchronization is challenging due to delays, randomness, and security concerns when transferring reference time across networks, and direct connection to primary time sources is often impractical and expensive, risking compliance with record-keeping requirements and stability.
Innovation Solution
A virtual clock switch module that receives reference time from multiple sources, transforms it into suitable formats, and supplies it to guest operating systems, providing increased accuracy, security, and redundancy, without modifying the guest operating system, using physical and pseudo clock drivers to handle latency and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference time is transferred across computer networks via NTP or PTP, then time synchronization is achieved, but delays and randomness are introduced reducing accuracy
Solution Approach 1:
The patent introduces a time server as an intermediary component that receives reference time from external sources and distributes it to virtual machines through a virtual switch. This mediator architecture separates the time synchronization function from direct network transfers, reducing the impact of network delays and randomness on VM timekeeping accuracy.
Solution Approach 2:
The time synchronization system is segmented into distinct functional components: external reference time sources, time server, virtual switch, and guest OS clock drivers. This segmentation allows each component to be optimized independently, with the time server handling external communications and the virtual switch managing internal distribution, thereby reducing overall synchronization errors.
2Measurement precision
If direct connection to primary time reference sources is established, then time accuracy is improved, but cost and complexity increase significantly
Solution Approach 1:
The patent creates a virtual copy of the time synchronization interface that presents a simplified model to virtual machines while handling complex reference time acquisition behind the scenes. The virtual switch and time server together form a software-based time reference system that replicates the functionality of expensive hardware clocks without requiring physical connection to primary time sources.
Solution Approach 2:
Instead of requiring expensive, permanent hardware clock devices with direct connections to primary time references, the system uses software-based time servers that can be deployed on standard hardware. The virtual switch and time synchronization software provide adequate accuracy for most applications without the cost and complexity of dedicated hardware time reference systems.
3Measurement precision
If reference time is transferred over networks, then time synchronization is provided, but security risks from tampering and intentional error increase
Solution Approach 1:
The time server acts as a trusted intermediary that validates and secures reference time before distributing it to virtual machines. This mediator can implement security measures such as authentication of time sources, encryption of time data, and validation of time stamps, protecting the virtualized environment from malicious time manipulation while maintaining synchronization accuracy.
4Productivity
If virtual machines share physical hardware, then resource utilization is improved, but clock jitter increases due to kernel scheduling latency and resource contention
Solution Approach 1:
The virtual switch serves as an intermediary time distribution layer that isolates virtual machines from host kernel scheduling variations. By providing time references through the virtual switch rather than through direct host OS clock interfaces, the system reduces the impact of kernel scheduling latency and resource contention on VM clock stability, allowing multiple VMs to share hardware while maintaining individual time accuracy.
Data Source
AI summary
A virtual clock switch permits accurate transfer of reference time from a variety of different time sources, transforms the reference time representation into one of a collection of different formats, and makes the reference time available to guest operating system instances running as virtual machines. As a result, reference time accuracy is increased, security improved, and the opportunity for providing redundancy in the event of hardware or software failures. Also, the ability to morph time formats allows the concept to be applied to guest virtual machines without the need to modify the guest operating system.