VM exit

Virtualization and Performance: Understanding VM Exits

VM exits in response to certain instructions and events (e.g., page fault) are a key source of performance degredation in a virtualized systems. But have you ever wondered why? What exactly happens during a VM exit anyway?

A VM exit marks the point at which a transition is made between the VM currently running and the VMM (hypervisor) which must exercise system control for a particular reason. In general, the processor must save a snapshot of the VM's state as it was running at the time of the exit. For Intel architectures, here is an approximation of the steps:

VM exit abonnieren