VCPU Host-Mode Timing for Accurate Virtualization Overhead Monitoring
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Solution Overview
Problem
Existing virtualization performance monitoring methods are inaccurate as they rely solely on the number of virtualization exits, which can lead to misleading results in scenarios where the overhead is significant despite low exit frequency, such as lock competition in the VMM.
Innovation Solution
Monitor virtualization overhead by determining CPU usage in the host mode based on time stamps of VCPU processes entering and exiting virtual machine mode, executing target instructions, and receiving wake-up instructions, using CPU usage as a quantitative indicator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If virtualization overhead is measured by the number of VCPU exits from virtual machine mode to host mode, then the measurement method is simple, but the measurement precision is low and cannot accurately reflect actual overhead
Solution Approach 1:
The patent changes the measurement parameter from counting virtualization exit events to measuring CPU usage through time stamps. Instead of simply counting how many times VCPU exits virtual machine mode, the system records entry and exit time stamps, calculates actual CPU usage in host mode, and uses this as the overhead metric. This parameter transformation resolves the contradiction by providing accurate measurement without excessive complexity.
2Measurement precision
If CPU usage is measured by recording time stamps of VCPU entering and exiting virtual machine mode, then the virtualization overhead measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The monitoring system leverages existing CPU time stamp resources and VCPU state information that are already available in the virtualization infrastructure. Rather than introducing complex external monitoring hardware or software, the system uses self-generated time stamps from the VCPU entry/exit events and existing CPU usage data to calculate overhead. This self-service approach improves measurement accuracy while minimizing additional system complexity.
3Device complexity
If traditional virtualization exit counting method is used, then the monitoring apparatus is simple, but it cannot accurately detect overhead in scenarios with low exit frequency but high actual overhead
Solution Approach 1:
The patent replaces the mechanical counting approach with a time-based measurement system. Instead of mechanically counting exit events, the system uses time stamp recording and CPU usage calculation to measure overhead. This substitution enables reliable detection of overhead in scenarios where traditional counting fails, such as when lock competition in VMM causes high overhead without frequent virtualization exits. The time-based measurement captures the actual impact on CPU resources regardless of exit frequency.
Data Source
AI summary
The present disclosure relate to a virtualization performance monitoring method and apparatus, a device and a medium, the method comprises: acquiring a first time stamp of a virtual central processing unit VCPU process entering a virtual machine mode and a second time stamp of the VCPU process exiting from the virtual machine mode to a host mode; acquiring a third time stamp of the VCPU process executing a target instruction in the host mode and a fourth time stamp of the VCPU process receiving a wake-up instruction in the host mode, the target instruction being an instruction for causing a CPU to enter a suspended state; determining a CPU usage occupied by the VCPU process running in the host mode based on the first time stamp, the second time stamp, the third time stamp and the fourth time stamp; and determining a virtualization overhead based on the CPU usage.