Dynamic Interrupt Assignment for Virtual Machine I/O Latency
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Solution Overview
Problem
Current server-class systems with large I/O fabrics experience high latency and poor performance due to congestion of interrupts from I/O devices, which affects the efficiency of data transfers and overall system performance.
Innovation Solution
A system and method for dynamically assigning interrupts to a virtual machine based on I/O metrics, where an interrupt manager monitors latency, usage levels, and transfer rates to update virtual interrupt assignments in a logical interrupt table, optimizing performance by reallocating interrupts as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static interrupt assignments are used in virtualized I/O systems, then system configuration is simple and stable, but interrupt latency increases and performance deteriorates under high data transfer rates
Solution Approach 1:
The patent implements dynamic interrupt assignment where the hypervisor continuously monitors I/O traffic metrics and adjusts interrupt allocations in real-time based on actual workload demands. This allows the system to adapt interrupt assignments dynamically rather than using static configurations, resolving the contradiction between stability and latency by maintaining stability through controlled adaptation.
Solution Approach 2:
The system employs feedback mechanisms by monitoring I/O traffic metrics such as data transfer rates and queue depths, then using this information to adjust interrupt assignments. The hypervisor receives feedback about system performance and configuration state, processes this information, and makes informed decisions about interrupt allocation to optimize latency while maintaining system stability.
2Productivity
If more interrupts are allocated to virtual machines, then data transfer performance improves, but interrupt congestion increases and overall system latency worsens
Solution Approach 1:
The patent applies local quality by allocating interrupt resources differently to different virtual machines based on their specific I/O workload characteristics. Rather than uniform allocation, each VM receives interrupt assignments tailored to its local needs, allowing high-throughput VMs to receive more interrupts while preventing overall system congestion through differentiated resource distribution.
Solution Approach 2:
The system changes the parameter of interrupt allocation dynamically based on monitored I/O traffic conditions. When data transfer rates increase or latency thresholds are approached, the hypervisor adjusts interrupt assignment parameters in real-time, allowing the system to optimize the balance between throughput and latency by varying these parameters according to actual workload demands.
3Speed
If interrupt assignments are updated frequently to optimize performance, then system responsiveness improves, but configuration complexity and overhead increase
Solution Approach 1:
The patent implements periodic action by updating interrupt assignments at scheduled intervals or based on trigger events such as threshold crossings in I/O metrics. Rather than continuous adjustment which would increase complexity, the system performs periodic reconfiguration based on monitored conditions, maintaining responsiveness while controlling configuration overhead through event-driven or time-based update cycles.
Data Source
AI summary
A system and method dynamically assign interrupts to a virtual machine from an input/output (I/O) adapter based on I/O metrics of the I/O adapter. An interrupt manager monitors I/O adapter traffic flow metrics such as latency of data transfers, usage levels, and transfers per unit of time. The interrupt manager determines when a traffic flow metric for a virtual machine meets a predetermined performance threshold and updates virtual interrupt assignments in a logical interrupt table to improve performance of the system.