Number of Virtual Processors (vCPUs) in Intel® Xeon® Processors
Wondering how many vCPUs (Virtual CPUs or Virtual Processors) are in an Intel® Xeon® Processor
There is no specific amount, ratio, or formula to determine the number of Virtual CPUs (vCPUs or Virtual Processors) from a physical CPU (pCPU or physical processor). Determining the ratio or how many vCPUs to allocate (or provision or subscribe) is dependent on the operating system used and the application or workload being virtualized.
Some operating systems and software applications view the physical processor as logical processors. A logical processor is the number of the processor's cores multiplied by the number of threads per core. vCPUs are actually the amounts of of time a virtual machine gets on a logical processor. The number of cores and threads of an Intel processor can be found in the Intel's Technical Specifications website by searching by processor number.
Some operating systems will have a maximum on number of vCPUs. It is recommended to start with 1:1 vCPU-to-pCPU ratio, and then scale up the number of vCPUs while assessing performance.
If using VMware*, it's recommended to check the VMware documentation on how to best subscribe or provision vCPU resources. Some suggested VMware website resources include:
- Virtual CPU Configuration
- Determining an Appropriate vCPU-to-pCPU Ratio
- VMware community post Core,Logical CPU,vCPU Explained
- The CPU Scheduler in VMware vSphere* 5.1
If using Windows*, some suggested website resources for information related to vCPUs include:
- Hyper-V Concepts: vCPU (Virtual Processor) - Q&A
- Requirements and Limits for Virtual Machines and Hyper-V in Windows Server 2008 R2
- Virtual machine sizing guidance
- Microsoft community post vCPUs are actually the amounts of of time a virtual machine gets on a logical processor