Since the rise of low-cost virtualization in 1999 with the first release of VMware Workstation, the public has rallied around the many benefits of virtualization. However, users might often wonder how to minimize the performance penalties they are paying when they work with virtualization technology.

The exact shape of virtualization's performance footprint has evolved as the field has matured. When 400MHz processors were first appearing on the market, the limiting factors posing an obstacle to widespread use of virtualization were CPU speed and RAM. This situation improved as Moore's law continued its inexorable march, providing both the processing power and the memory space sufficient for multiple virtual machines to run at once on the same hardware, and thereby opening the way for the flourishing server virtualization market.

A second performance challenge arises from the intrinsic ability of virtualization to allow overcommitting of physical resources. Assigning more (virtual) processors to a set of virtual machines than the physical machine happens to have is an acceptable choice under a low service load, but as one or more of the hosted workloads experiences peak usage, a dynamic resource load-balancing scheme is required. Virtual machine migration, termination of VMs hosting lower priority tasks, or equivalent approaches must be orchestrated through a supervising logic to ensure that the service level is guaranteed, even as the performance "insurance" of physical machine separation is removed.

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