Virtualization Software Independent Time Sources for Virtual Machines

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Solution Overview

Problem

In high-availability systems with virtualization, providing independent time sources for real-time operating systems is challenging due to shared resource access issues, leading to latency and performance deterioration, especially when multiple virtualized automation systems share the same hardware platform.

Innovation Solution

A method and virtualization software that assign independent time sources to each virtual runtime environment, using a processor core exclusively for each real-time operating system, with the virtualization software updating memory cells as time sources without interrupting the virtual machine, allowing direct access to time stamp counters and real-time clock modules without going through the hypervisor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple virtualized systems share the same hardware platform and access shared resources like RTC through the hypervisor, then resource utilization is improved, but latency increases and real-time performance deteriorates

Engineering Contradiction:
Improveresource sharingVSAvoidlatency
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent segments the time source functionality by providing each virtual machine with dedicated time stamp counters (TSC) that are directly accessible without hypervisor intervention. This segmentation allows VMs to obtain time information independently, eliminating the latency caused by shared resource access through the hypervisor while maintaining resource utilization efficiency.

Inventive Principle:
Principle #1Segmentation

2Productivity

If a real-time operating system uses shared time sources accessed through virtualization software, then system consolidation is improved, but operational reliability and independence of time sources deteriorates

Engineering Contradiction:
Improvesystem consolidationVSAvoidtime source independence
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by providing each virtual machine with its own dedicated time stamp counter that is exclusively accessible by that VM. This ensures that each VM has a locally independent time source with guaranteed accuracy and reliability, while the system as a whole achieves high consolidation through efficient resource management. The RTC module serves as an additional independent time source that can be virtualized and shared when needed.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2575002B1Method and virtualisation software for producing independent time sources for virtual runtime environments
Publication Date: 2018.02.21 SIEMENS AG
  • EP2575002B1 patent drawingFigure 1

AI summary

The method involves exclusively associating real-time operating systems (RTOS1-RTOS3) with secondary time sources (TSC1-TSC3) that are provided in secondary processor cores (Core1-Core3). A primary time source (RTC) is provided for periodically transmitting interrupt signal (INIT) to a primary processor core (Core0). An overall operating system (GPOS) is operated based on clock signal generated by a virtualization clock module (VRTC), and numerical content of readable memory registers (AZ1-AZ3) are incremented by secondary time sources during existence of interrupt signal.