Hypervisor Interrupt Routing via MDA Mapping
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Solution Overview
Problem
In virtualized computer systems, the current methods for interrupt routing result in increased latency due to the need to cycle through data structures storing the contents of APIC registers for active virtual processors, which is inefficient and exceeds acceptable processing times.
Innovation Solution
The implementation of a hypervisor-supported data structure that maps message destination addresses (MDA) to virtual processors for both physical and logical interrupt destination modes, allowing for direct identification and routing of interrupts without the need to cycle through APIC register contents, thereby reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system cycles through data structures storing APIC register contents to identify virtual processors for interrupt routing, then the system can maintain compatibility with existing interrupt handling mechanisms, but the interrupt processing latency increases beyond acceptable levels
Solution Approach 1:
The patent pre-computes and stores the mapping between message destination addresses (MDA) and virtual processor identifiers in a dedicated data structure before interrupt handling is needed. This preliminary action eliminates the need to cycle through APIC register contents at interrupt handling time, thus reducing latency while maintaining compatibility with existing interrupt mechanisms that use MDA for virtual processor identification.
2Productivity
If the system uses a straightforward data structure mapping approach to reduce interrupt latency, then interrupt processing speed improves, but the device complexity increases due to additional data structures
Solution Approach 1:
The patent creates a simplified copy or projection of the APIC register mapping relationship in the form of an MDA-to-virtual-processor mapping data structure. This copy contains only the essential routing information needed for interrupt handling, eliminating the need to navigate complex nested data structures while preserving the essential routing functionality, thus improving speed without proportionally increasing complexity.
Data Source
AI summary
Systems and methods for injecting interrupts in a virtualized computer system. An example method may comprise providing a data structure associating message destination addresses and virtual processor identifiers for a plurality of interrupt destination modes, receiving an interrupt message including a message destination address, looking up the message destination address in the data structure, and forwarding the interrupt message to a virtual processor associated by the data structure with the message destination address.