2V0-620 · Question #27
An application running in a virtual machine is experiencing performance issues. When utilizing performance monitoring utilities, it is noted that the CPU Utilization of the application is at 100%…
The correct answer is A. There is a network I/O constraint. B. There is a storage I/O constraint. In a virtualized environment, both network and storage I/O bottlenecks can force the application's vCPU to busy-wait or spin, driving guest CPU utilization to 100%. Disk space exhaustion and lack of virtualization awareness do not directly cause this symptom.
Question
An application running in a virtual machine is experiencing performance issues. When utilizing performance monitoring utilities, it is noted that the CPU Utilization of the application is at 100%. Which two scenarios are probable causes of the CPU contention for the application? (Choose two.)
Options
- AThere is a network I/O constraint.
- BThere is a storage I/O constraint.
- CThere is insufficient disk space assigned to the virtual machine.
- DThe application is not virtualization aware.
How the community answered
(30 responses)- A83% (25)
- C10% (3)
- D7% (2)
Why each option
In a virtualized environment, both network and storage I/O bottlenecks can force the application's vCPU to busy-wait or spin, driving guest CPU utilization to 100%. Disk space exhaustion and lack of virtualization awareness do not directly cause this symptom.
A network I/O constraint causes the application to perform excessive retries or busy-poll the network stack waiting for responses, consuming CPU cycles and pushing utilization to 100% even though the real bottleneck is the network.
A storage I/O constraint results in high I/O wait time where the guest OS and application spin or repeatedly poll for storage responses, inflating CPU utilization metrics to 100% while the actual bottleneck is disk throughput or latency.
Insufficient disk space causes write failures or out-of-space errors in the application but does not create CPU busy-spinning or contention that would drive utilization to 100%.
An application lacking virtualization awareness may suffer from suboptimal performance due to paravirtualization gaps, but this condition alone does not directly produce the 100% CPU utilization pattern described.
Concept tested: I/O constraints causing guest CPU utilization spikes
Source: https://docs.vmware.com/en/VMware-vSphere/6.0/com.vmware.vsphere.monitoring.doc/GUID-F940CBCC-8657-4C76-8C2B-6DBEA8F7BBFF.html
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