Hypervisor Virtual Processor Scheduling for Guest OS Latency
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Solution Overview
Problem
In hypervisor-controlled computing environments, the overhead from multiple scheduling levels can lead to unacceptable latency, especially when real-time operating systems are integrated, as conventional guest operating systems' task priority information is not accessible to the hypervisor, resulting in inefficient task scheduling.
Innovation Solution
Implementing 'thin' guest operating systems with limited or no scheduling functions, relying on the hypervisor for scheduling and task prioritization, allowing the hypervisor to create and manage virtual processors with priorities assigned by the guest operating systems, thereby simplifying the scheduling process and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple levels of scheduling are implemented (hypervisor level and individual operating system level), then multiple operating systems can be supported, but system overhead increases and latency is unacceptable for real-time operating systems
Solution Approach 1:
The patent extracts the scheduling function from individual guest operating systems and consolidates it at the hypervisor level. Guest operating systems are transformed into 'thin' versions that lack scheduling capabilities, while the hypervisor becomes the sole scheduling authority. This extraction eliminates redundant scheduling layers and reduces context switching overhead, directly addressing the latency problem while maintaining multi-OS support through virtualized resource management.
Solution Approach 2:
The patent merges the scheduling functions of multiple operating systems into a single unified hypervisor scheduler. Instead of having separate schedulers in each guest OS that independently manage tasks, all scheduling decisions are centralized in the hypervisor, which has visibility into task priorities across all guest operating systems. This consolidation eliminates the need for multiple scheduling layers and reduces overall system overhead.
2Reliability
If real-time operating system is given highest priority in conventional hypervisor scheduling, then real-time tasks can execute, but scheduling efficiency decreases because task priority information is not accessible to the hypervisor
Solution Approach 1:
The patent implements a feedback mechanism where task priority information from guest operating systems is communicated to the hypervisor scheduler. The hypervisor receives priority data from each guest OS and uses this feedback to make informed scheduling decisions. This allows the hypervisor to dynamically adjust scheduling based on actual task priorities, ensuring real-time tasks receive appropriate priority while maintaining overall scheduling efficiency through informed decision-making.
3Ease of operation
If conventional guest operating systems with built-in schedulers are used, then each OS can independently manage its tasks, but the hypervisor cannot access task priority information for efficient cross-OS scheduling
Solution Approach 1:
The patent extracts the scheduling function from guest operating systems, transforming them into thin versions that rely on the hypervisor for scheduling. This extraction allows the hypervisor to directly access task priority information without being blocked by guest OS scheduler abstractions, while still maintaining the ability to manage tasks across multiple operating systems through centralized control.
Data Source
AI summary
An apparatus includes a processor and a guest operating system. In response to receiving a request to create a task, the guest operating system requests a hypervisor to create a virtual processor to execute the requested task. The virtual processor is schedulable on the processor.