A few days ago someone forwarded me a blog article with an interesting claim about KVM performance:
Testing results from internal and customers showed SAP workloads: 85-95, Oracle OLTP: 80-92% bare metal. LAMP stack showed better than bare metal performance. Whitepapers will be published in how this was achieved. Java achieved up to 94% bare metal.
Frankly, I was surprised to hear this. KVM is a hosted virtualization platform, equivalent to the free VMware Server, which runs on top of a host operating system. VMware server is fine for a virtual machine or two, but you would not want it hosting your critical business applications. The above KVM claim suggests that KVM possesses hypervisor-like performance. So we ran a test with a few virtual machines to see what we could learn. These tests confirmed my suspicions: KVM is a very long way from enterprise-class virtualization performance.