KVM outperforms Xen

Even without extensive Xen and KVM performance benchmarking, there are many reasons to explain why Linux leaders such as Red Hat and Ubuntu are treating KVM. The most obvious and important factor is that KVM is part of the Linux kernel, and Xen is just a product that is installed under the Linux kernel.

Why is this so important? It is important because the patch package in the Xen work environment in the past is not compatible with the Linux kernel. But if you implement KVM, this problem can be easily solved. Another reason for choosing KVM is that KVM is deployed inside the Linux kernel, which makes it easy to control the virtualization process.

Xen advocates claim that KVM is not as mature as Xen technology and lacks some key features such as dynamic migration and pan-virtualization support. Indeed, the pan-virtualization technology in the Xen work environment can make virtual machine operations more efficient because the pan-virtualization technology interacts directly with the hardware. However, the use of pan-virtualization technology requires modification of the operating system
, and the default installation of Windows
does not support the pan-virtualized working environment. As for dynamic migration, KVM can do it, just need to install the correct KVM version. KVM used to have a problem with dynamic migration in the past, but it has now been resolved.

From another perspective, KVM is more flexible. Because the operating system interacts directly with the hypervisor integrated into the Linux kernel, it can interact directly with the hardware in any scenario without having to modify the virtualized operating system. This is very important because KVM can be a faster solution for virtual machine operations. The fact that KVM requires Pacifica (AMD) or Vanderpool (Intel) to virtualize CPUs is no longer a limiting factor for KVM development, as most server CPUs currently have these processors.

One of the credible reasons for not choosing KVM virtualization technology is that Xen is a bit longer and the product is more mature. But in the long run, Xen will make the Linux kernel more and more burdensome, because Xen lacks good integration (and will not solve this problem in the future), although Xen developers are actively addressing this integration issue.

The last point is that KVM is part of the Linux kernel, and Xen is best integrated into Linux. Over time, Ret Hat (currently mastering KVM technology), as the largest share of the Linux enterprise market, will make the latecomer of virtualization technology & ndash; KVM as full-featured as Xen. I believe that the future virtualization market must be KVM.