ACPI Notification Queue for Virtual Machine Event Synchronization
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Solution Overview
Problem
Virtual machines face challenges in managing simultaneous power management events due to the lack of specific methods in the ACPI standard for sequencing and prioritizing event handling, which can lead to incorrect device configurations and inefficiencies.
Innovation Solution
The implementation of ACPI Notification Queues (ANQs) to store and handle power management events in a first-in-first-out order, allowing for synchronized and prioritized event handling, with the option to create multiple queues for parallel processing and mutual exclusion where necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple power management events are handled simultaneously in a virtual machine, then event processing speed is improved, but event sequencing accuracy deteriorates leading to configuration errors
Solution Approach 1:
The patent segments the handling of power management events by introducing separate FIFO queues for different event types (e.g., hot-plug events, power state transitions). Each queue independently manages its event sequence, preventing interleaving conflicts while maintaining overall parallel processing capability. This segmentation resolves the contradiction by allowing simultaneous queue processing (improving speed) while ensuring strict sequencing within each queue (maintaining accuracy).
Solution Approach 2:
The patent introduces an intermediary notification queue mechanism between event sources and event handlers. The queue acts as a buffer that receives events from multiple sources, orders them according to FIFO principles, and delivers them to handlers in a controlled manner. This intermediary structure enables parallel event acceptance while guaranteeing sequential processing, thus resolving the speed-accuracy contradiction.
2Reliability
If event handlers wait for previous events to complete before starting, then event handling accuracy is improved, but system responsiveness deteriorates
Solution Approach 1:
The patent divides the monolithic event handling process into multiple independent parallel streams, each managed by separate FIFO queues. Multiple event handlers can process different queues simultaneously, achieving system-level parallelism. This segmentation allows the system to maintain high responsiveness through concurrent processing while ensuring accuracy within each individual event stream through strict FIFO ordering.
Solution Approach 2:
The patent implements dynamic event processing where the system adapts its handling strategy based on event type and queue state. Different queues can be processed in parallel when they contain independent events, while maintaining sequential processing within each queue when events require ordering. This dynamic approach optimizes both responsiveness and accuracy based on real-time conditions.
Data Source
AI summary
A method for synchronizing the handling of events in a computer using the Advanced Configuration and Power Interface (ACPI) standard is presented, wherein an ACPI Notification Queue (ANQ) is provided to store events, such that such events can be handled in first-in-first-out order.