The final test was with 18-vCPU VMs that we sized to exactly match the number of physical cores in each processor. The results are shown in Figure 7.
Figure 7. 18 vCPU RHEL VM scale-out performance running Oracle and DVD Store 3 workload
The 18-vCPU VMs are advantaged in the lower number of VMs tests because the system is not overcommitted, and it is sized to exactly use the full resources of single socket. Each VM has more resources than the 16-vCPU VMs, and it puts them to good use and achieves performance that is better than the 16 vCPU VMs at 1, 2, 4, and 8 VMs. But at 12 VMs, its performance is lower than the 16-vCPU VMs. That extra 2 vCPUs per socket are available to be used by the load driver VM and all of the vSphere infrastructure including vSAN, NSX, and vCenter.