VCP-DCV vSphere Performance and Scaling Practice Question
An administrator is troubleshooting a VM that is running slowly. The VM has 4 vCPUs and 16 GB of memory. The host has 2 physical CPUs with 10 cores each, hyper-threading enabled. The administrator runs esxtop and sees that %RDY for the VM is consistently above 15%. Which action would most likely reduce the ready time?
⚠ Common exam trap
It's easy for candidates to assume adding more vCPUs will improve performance, but in reality, over-provisioning vCPUs increases co-scheduling overhead and ready time, making reduction the correct fix.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Reduce the number of vCPUs to 2 if the workload does not require 4.
A %RDY value consistently above 15% indicates the VM is ready to run but is waiting for CPU scheduling time on the host. With 4 vCPUs on a host that has 20 logical CPUs (2 sockets × 10 cores × 2 threads), the VM is likely over-provisioned relative to its workload needs, causing co-scheduling contention. Reducing the number of vCPUs to 2 decreases the co-scheduling demands and reduces ready time, as the VM will require fewer physical CPUs to be available simultaneously. Therefore, option D is correct. Increasing CPU shares (option A) would not help if the host is saturated, adding more vCPUs (option B) would worsen contention, and increasing memory (option C) does not address CPU ready time.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the CPU shares for the VM.
Why it's wrong here
Increasing CPU shares does not reduce ready time if the host is saturated because shares only affect proportional distribution, not overall contention; if the host is overloaded, shares won't help.
- ✗
Increase the number of vCPUs to 8 to improve parallelism.
Why it's wrong here
Adding more vCPUs increases co-scheduling demands and likely worsens ready time, as the VM will need even more physical CPUs simultaneously.
- ✗
Increase the memory allocation to 32 GB.
Why it's wrong here
Increasing memory allocation does not address CPU scheduling contention; ready time is a CPU metric, not memory.
- ✓
Reduce the number of vCPUs to 2 if the workload does not require 4.
Why this is correct
Reducing the number of vCPUs to match the workload's parallelism reduces co-scheduling overhead and thus lowers ready time, making this the correct action.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This VCP-DCV practice question is part of Courseiva's free VMware certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the VCP-DCV exam.