VCP-DCV vSphere Performance and Scaling Practice Question
A vSphere administrator is troubleshooting performance issues in a cluster with 4 ESXi hosts, each with 2 sockets of 16-core CPUs (32 logical processors per host). The cluster runs 80 VMs, each with 4 vCPUs, and users report slow application response. The administrator observes high CPU ready time on the VMs. Which TWO actions would be most effective in reducing CPU ready time while maintaining performance? (Choose two.)
⚠ Common exam trap
The trap here is thinking that adjusting CPU shares or enabling affinity will reduce ready time, when in fact shares only redistribute contention and affinity can limit scheduler flexibility, often increasing ready time.
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 per VM to match actual workload demand.
High CPU ready time indicates that VMs are waiting for physical CPU resources. Reducing vCPU count per VM lowers co-scheduling demands and contention, while adding hosts increases the total physical cores available, both directly reducing ready time. The other options either do not address the root cause or can worsen performance by restricting scheduling flexibility or reducing capacity.
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 all VMs to high priority.
Why it's wrong here
CPU shares determine relative priority during contention, but setting all VMs to high shares makes them equal, so no VM gains an advantage. Shares do not reduce overall contention or ready time; they only affect distribution when there is competition. This action does not address the root cause of high ready time, which is excessive vCPU allocation relative to physical cores.
- ✓
Reduce the number of vCPUs per VM to match actual workload demand.
Why this is correct
Reducing vCPU count per VM decreases the number of virtual CPUs that the host scheduler must co-schedule, which can significantly lower CPU ready time. Many workloads do not require all allocated vCPUs, and over-provisioning vCPUs leads to co-scheduling overhead and increased ready time. Right-sizing VMs to their actual demand reduces contention and improves scheduling efficiency.
- ✓
Add more ESXi hosts to the cluster to increase the total number of physical cores.
Why this is correct
Adding hosts increases the total physical CPU resources available in the cluster. With more cores, the ratio of vCPUs to physical cores decreases, reducing contention and allowing the scheduler to run VMs without waiting. This directly lowers CPU ready time because VMs have more opportunities to be scheduled on available cores. It is a scalable solution when the cluster is genuinely under-resourced.
- ✗
Enable CPU affinity for all VMs to pin them to specific physical cores.
Why it's wrong here
CPU affinity can reduce scheduling flexibility and may cause imbalances, leading to higher ready time for VMs that cannot run on busy cores. While affinity can be useful for niche cases, it is not a general solution for reducing CPU ready time in an overcommitted cluster. It often exacerbates the problem by preventing the scheduler from efficiently distributing load across all cores.
- ✗
Disable hyperthreading on all hosts to ensure each vCPU maps to a physical core.
Why it's wrong here
Disabling hyperthreading reduces the number of logical processors, which decreases scheduling capacity and likely increases CPU ready time. Hyperthreading allows the scheduler to use logical cores for additional parallelism, and while it can introduce some contention, it generally improves throughput for many workloads. Disabling it is counterproductive in an overcommitted environment.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official VMware exam blueprint
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