Performance and scalability are key concerns when hosting applications in virtual machines. The x86 processor was not originally designed to support virtualization. As a result, workloads virtualized on x86 virtual machine platforms will incur some performance overhead, particularly when performing I/O. Virtual machine platforms can implement a variety of optimizations to help reduce this overhead, including the use of efficient hypervisors optimized for managing resources; paravirtualization, which enables operating systems to cooperate with the host for managing resources efficiently; and exploitation of emerging virtualization hardware in x86/x64 processors.

Also, as virtual machines are used to host increasingly demanding workloads, the scalability of virtual machine platforms becomes a concern. Virtual machine platforms can build in a variety of functions that allow critical workloads to perform well even under heavy or rapidly changing workloads. Such scalability-enhancing optimizations can be implemented in memory management; the ability for virtual machines to use multiple virtual processors at a time in shared memory processing (SMP) configurations; and support for 64-bit computing.

Click on one of the links below to see how the studied products compare in supporting these functions:

	VM Host Architecture (8 ratings)
	Memory Management (21 ratings)
	Paravirtualization (12 ratings)
	Virtualization Hardware Support (8 ratings)
	Virtual SMP Support (4 ratings)
	64-bit Support (8 ratings)