Hypervisor Clock Component for Virtual Device Timing
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Solution Overview
Problem
Virtual machines lack direct access to accurate and precise clock times due to the inefficiency of emulating a real-time clock device, which increases computing resources usage and decreases precision, making it unsuitable for operations requiring precise timing, such as network synchronization.
Innovation Solution
A clock component within the hypervisor continuously obtains and writes current clock times from a real-time clock device to a memory location accessible by virtual devices, allowing them to obtain accurate and precise clock times without the need for resource-intensive emulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a real-time clock device is emulated in the hypervisor to provide clock times to virtual devices, then virtual devices can access clock times, but computing resources usage increases and precision decreases
Solution Approach 1:
The patent extracts the clock time data from the emulated RTC device and places it directly into a memory location that virtual devices can access. This separates the clock time generation function from the emulation overhead, allowing virtual devices to read precise clock times directly from memory without going through the emulated device interface, thereby reducing computing resource usage while maintaining precision.
Solution Approach 2:
The patent introduces a memory location as an intermediary between the real-time clock device and virtual devices. Instead of virtual devices interacting with an emulated RTC device, they directly access the memory location where clock times are stored, eliminating the emulation layer and its associated resource overhead while preserving time precision.
2Ease of operation
If a real-time clock device is emulated in the hypervisor, then virtual devices can obtain clock times, but the clock times may lag behind real time
Solution Approach 1:
The patent extracts clock time data directly from the real-time clock device and stores it in a memory location accessible by virtual devices. This bypasses the emulated RTC device that causes timing lag, allowing virtual devices to access accurate real-time clock values directly without the delays introduced by emulation.
Solution Approach 2:
The hypervisor continuously updates the memory location with current clock times from the real-time clock device in advance. This ensures that when virtual devices read from the memory location, they immediately obtain up-to-date accurate time values without waiting for emulation cycles or experiencing lag.
3Measurement precision
If clock times are continuously updated in memory for virtual device access, then precision is improved, but memory access overhead increases
Solution Approach 1:
The patent merges the clock time storage function with the existing memory management infrastructure of the hypervisor. By using a memory location that is already part of the hypervisor's address space and management system, the solution avoids creating separate complex storage mechanisms, thereby reducing overall system complexity while maintaining continuous update capability for precise timing.
Data Source
AI summary
Providing clock times to virtual devices. In one embodiment, a method includes identifying a real-time clock device of a host computing device. The host computing device comprises a hypervisor and a virtual machine. The method also includes determining that a virtual device used by the virtual machine will use clock times obtained from the real-time clock device. The method further includes obtaining, by a processing device of the host computing device, a current clock time from the real-time clock device of the host computing device. The method further includes providing the current clock time to the virtual device.