Virtual CPU Starvation Detection via Timer Interrupt Delta Analysis

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Solution Overview

Problem

In virtualized environments, identifying and addressing resource starvation in virtual machines (VMs) is challenging due to co-existing VMs on the same host system, leading to delays in vCPU scheduling, which can cause issues like packet processing delays and connection loss, especially when the underlying host system lacks visibility into its status.

Innovation Solution

The system detects vCPU scheduling delays by calculating the delta between expected and actual timer interrupt firing times, generates historical data, and predicts future delays using machine learning models, allowing for actions such as workload migration to mitigate resource starvation, prioritize protocol control packets, and adjust queue depths to prevent packet drops.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple virtual machines are deployed on the same host system to increase resource utilization, then productivity is improved, but virtual CPU resource starvation occurs causing scheduling delays and reliability degradation

Engineering Contradiction:
Improveresource utilizationVSAvoidvCPU scheduling reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary detection of vCPU scheduling delays by monitoring timer interrupt occurrences and calculating deltas between expected and actual interrupt times. Historical data is collected and stored before migration decisions are made, enabling predictive analytics to anticipate resource starvation conditions and take preventive actions before critical failures occur.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback loops by monitoring vCPU scheduling performance metrics, comparing actual timer interrupt times against expected times, and using this feedback to trigger workload migration when thresholds are exceeded. The system also provides visibility to cloud service providers about host system status and vCPU scheduling health, enabling informed decision-making.

Inventive Principle:
Principle #23Feedback

2Reliability

If resource reservation is implemented to prevent starvation, then reliability is improved, but scheduling delays still occur during high traffic periods

Engineering Contradiction:
Improveresource availabilityVSAvoidscheduling delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically adjusts resource allocation by migrating workloads between virtual machines based on real-time monitoring of vCPU scheduling delays. Instead of static resource reservation, the system uses predictive analytics on historical timer interrupt data to anticipate starvation conditions and proactively rebalance loads, adapting resource distribution to changing traffic conditions and preventing both starvation and excessive delays.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the host system lacks visibility into its status to simplify management, then ease of operation is improved, but the ability to detect and diagnose resource starvation is reduced

Engineering Contradiction:
Improvemanagement simplicityVSAvoidresource starvation detection
Core Design Contradiction:
Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system implements self-service monitoring by automatically detecting vCPU scheduling delays through timer interrupt analysis without requiring manual intervention or complex external monitoring tools. The system autonomously collects historical data, performs predictive analytics, and executes workload migration decisions, providing cloud service providers with visibility into host system status and vCPU scheduling health while maintaining management simplicity through automated operations.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS20230125661A1Systems and methods for detecting and predicting virtual CPU resource starvation of a virtual machine
Publication Date: 2023.04.27 CITRIX SYSTEMS INC
  • US20230125661A1 patent drawing
  • US20230125661A1 patent drawing
  • US20230125661A1 patent drawing

AI summary

Described embodiments provide systems and detecting and predicting virtual CPU resource starvation of a virtual machine. One or more processors can determine, within a time period, a count of a number of delays in occurrences of a timer interrupt scheduled for a virtual processor of a virtual machine executing an application. The one or more processors can compare the count of the number of delays with a threshold established for the time period. The one or more processors can execute a process to migrate the application to a second one or more processors based at least on the comparison of the count of the number of delays with the threshold.