Processor and Core Allocation in Azure VMs

​Allocation of physical processor resources to Azure VMs can vary depending on the underlying host hardware, and the process is different from the common on-premises practice of oversubscription.This illustration presents examples of different allocation scenarios.

Azure VM host hardware uses physical processors (CPUs), each of which has multiple physical compute cores. 

For earlier generations of Azure VM host hardware that do not support Hyper-Threading (top), physical cores are allocated to hosted Azure VMs, and each physical core allocated is seen by the virtualized guest OS as one single-core processor (called a virtualized CPU [vCPU]). 

Newer generations of Azure VM host hardware enable Hyper-Threading, a feature of Intel processors that allows two threads to queue in parallel (center). With Hyper-Threading enabled, a single physical core allocated to a VM appears as two vCPUs to the guest OS. Azure VM host servers do not allocate more total vCPUs than physical cores or physical core threads available.