Virtual Interrupt Filter for Virtualized Systems

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Solution Overview

Problem

In virtualized computing systems, excessive virtual interrupts generated by peripherals can overwhelm guest operating systems and evade detection by the hypervisor, degrading system performance due to offloaded interrupt processing.

Innovation Solution

A virtual interrupt filter with an estimator circuit provides an estimate of the proportion of interrupts that are virtual, allowing for the detection of excessive interrupts and subsequent blocking of incoming interrupts when a threshold is met.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If interrupt processing is offloaded to the virtual interrupt controller, then system performance is improved, but the hypervisor loses the ability to detect and protect against excessive virtual interrupts

Engineering Contradiction:

Improvesystem performanceVSAvoiddetection capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A virtual interrupt filter is introduced as an intermediary component between the virtual interrupt controller and guest operating systems. This filter monitors virtual interrupts independently, providing detection capabilities without interfering with the offloaded interrupt processing path. The filter analyzes interrupt characteristics and blocks excessive interrupts before they reach the guest OS, thus maintaining both performance improvement and detection capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the virtual interrupt controller handles all virtual interrupts, then interrupt processing efficiency is improved, but excessive interrupts can overwhelm guest operating systems

Engineering Contradiction:

Improveinterrupt processing efficiencyVSAvoidsystem overload

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The virtual interrupt filter performs preliminary action by monitoring and analyzing virtual interrupts before they are delivered to guest operating systems. It maintains statistics about interrupt sources and proactively blocks excessive interrupts in advance, preventing system overload before it occurs. This early intervention preserves the efficiency benefits of offloaded processing while protecting against harmful effects.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the hypervisor processes all interrupts directly, then detection and protection capabilities are maintained, but system performance deteriorates

Engineering Contradiction:

Improvedetection capabilityVSAvoidsystem performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The interrupt processing function is segmented into two independent paths: (1) the virtual interrupt controller handles routine interrupt delivery to maintain high performance, and (2) the virtual interrupt filter independently monitors and detects excessive interrupts. This segmentation allows the hypervisor to relinquish routine processing while retaining detection capability through the specialized filter component.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9015374B2Virtual interrupt filter

Publication Date: 2015.04.21 ADVANCED MICRO DEVICES INC

AI summary

A system for processing interrupts in a virtualized computing environment includes a virtual interrupt controller to provide virtual interrupts from peripherals to virtual machines. The system also includes a virtual interrupt filter that has an estimator circuit to provide an estimate of what proportion of interrupts from one or more of the peripherals are virtual interrupts. A determination is made as to whether the estimate satisfies a criterion; if it does, incoming interrupts are blocked.