Nutanix Certified Associate Practice Exam

What two changes can enhance VM performance if a VM experiences high CPU ready percentage but low overall CPU utilization?

1. Reduce the number of vCPUs assigned to VMs

2. Add more memory to the VMs

3. Replace high core count CPUs with high clock rate CPUs

4. Reduce the number of VMs on the hosts

The correct answer is: Reduce the number of vCPUs assigned to VMs

When a virtual machine (VM) experiences a high CPU ready percentage alongside low overall CPU utilization, it indicates that the VM is facing scheduling issues, meaning it's waiting too long to get access to a CPU. Reducing the number of vCPUs assigned to VMs can significantly enhance performance in this scenario. When a VM is assigned more vCPUs than it can effectively utilize, it can lead to contention among VMs for CPU resources. Having an excess of vCPUs can complicate the scheduling process, as the hypervisor has to manage allocations for more vCPUs than necessary. By reducing the number of vCPUs, the VM can potentially make better use of the remaining available CPU resources, thereby reducing its CPU ready time. Assigning fewer vCPUs can also allow the hypervisor to schedule the VM more efficiently with the available physical CPU cores, which can lead to improved performance outcomes. This is particularly critical in environments where multiple VMs are competing for the same set of CPU resources, as it allows for better load balancing and resource allocation. While the other options may seem beneficial in certain contexts, they do not directly address the issue of high CPU ready times with low utilization as effectively as reducing the number of vCPUs does.