This chapter describes common sources of overhead in a QNX hypervisor system, and strategies for reducing this overhead and optimizing system performance.
A VM defines its guest's hardware environment. Once its guest is running, however, a VM is at the mercy of the guest's operations, much like hardware is at the mercy of the code it must execute.
The hypervisor must always respond to the needs of guests in its VMs. If a guest is not tuned for optimal performance in a hypervisor VM and for the board on which the hypervisor is running, the hypervisor can't do anything about the situation. For example, if a guest makes requests that generate numerous spurious interrupts (and, therefore, guest exits), the hypervisor can only attempt to handle these interrupts, in the same way that hardware must respond to the requests of a non-virtualized system.