Peak CPU utilization indicates the high-water mark of CPU usage as a percentage during the incremental use case tests. Each VMware virtualized database used 16 vCPUs for the OLTP workload tests. The following figure shows the peak CPU utilization across all 16 VMs—eight running Windows Server 2016 and eight running RHEL.
As shown in Figure 7, there was a noticeable peak CPU difference between the Windows VMs (blue bars) and Linux VMs (red bars). The Windows VMs had an average peak CPU utilization of 58.6 percent. The Linux VMs were approximately 17 points lower in peak CPU utilization, with an average of 41.2 percent.
In our testing, there were no statistics that explained the difference in peak CPU utilization between the two operating systems. Our recommendation is to closely monitor your virtualized SQL Server databases for peak CPU utilization and make the appropriate change in the number of reserved vCPUs. In cases of oversubscription of CPU resources, customers have found that using fewer vCPUs reduces processor instruction scheduling by the hypervisor and can increase performance.