Guest Interrupt Manager for Virtual Machine Latency Reduction
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Solution Overview
Problem
Virtualization environments experience significant latency in interrupt delivery due to software-based mechanisms, which can be up to 100 times longer than in non-virtualized environments, affecting performance and efficiency.
Innovation Solution
A system with a guest interrupt manager that maintains an interrupt request state for each destination guest, allowing for direct and efficient delivery of interrupts without software intervention, using a data structure to track and update interrupt states, and supporting atomic operations to ensure accurate and timely interrupt handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If software-based interrupt delivery mechanisms are used in virtualized environments, then interrupt delivery can be implemented with full virtualization support, but interrupt processing latency increases significantly (up to 100 times longer than non-virtualized environments)
Solution Approach 1:
The system segments interrupt handling into two distinct paths: a fast path for active guests that uses direct hardware access, and a slow path for inactive guests that uses software-based delivery. This segmentation allows the system to maintain full virtualization support while minimizing latency for the common case of active guests.
Solution Approach 2:
The patent introduces an intermediary mechanism (the interrupt request state data structure and guest interrupt manager) that mediates between the interrupt controller and inactive guests. This intermediary allows interrupts to be delivered to inactive guests without requiring full software-based processing, thus reducing latency while maintaining virtualization support.
2Loss of time
If direct hardware access is used for interrupt delivery, then interrupt processing latency is minimized, but virtualization control and security are compromised
Solution Approach 1:
The system applies local quality by allowing direct hardware access only for specific destinations (active guests) while maintaining software-based control for other destinations (inactive guests). The interrupt request state data structure tracks which guests are active, enabling the system to apply the appropriate delivery mechanism locally to each interrupt destination.
Solution Approach 2:
The system dynamically adjusts the interrupt delivery mechanism based on the operational state of the guest. When a guest is active, direct hardware access is used for low latency; when inactive, software-based delivery is used for security and control. The guest interrupt manager dynamically updates the interrupt request state to reflect current guest states.
Data Source
AI summary
In an embodiment, a system comprises a memory system configured to store a data structure. The data structure stores at least an interrupt request state for each destination in each of a plurality of guests executable on the system. The interrupt request state identifies which interrupts have been requested at the corresponding interrupt controller in the corresponding guest of the plurality of guests. A guest interrupt manager is coupled to receive an interrupt message targeted at a first destination in a first guest of the plurality of guests, and the guest interrupt manager is configured to update the interrupt request state in the data structure that corresponds to the first destination and the first guest.