Hacker News Reader

Comment by nnx | Hacker News Reader

What’s the benefit of KVM over Xen these days?

It's difficult to make an simple comparison because neither hypervisor is used "out of the box" by EC2. For example, a lot of hypervisor benchmark comparisons focus on I/O performance, but the latest generation EC2 instances offload networking and storage processing to hardware. This is the case for both for instances that use Xen and C5 that uses the new KVM-based hypervisor.

Since both hypervisors have very good support for hardware virtualization technology, it becomes more of an architecture decision. Practically speaking, it is a little bit easier to build a very small footprint hypervisor with the core KVM code than Xen.

I am also curious. I found this article which might help a little bit: https://www.theregister.co.uk/2017/01/30/google_cloud_kicked...

KVM can take better advantage of hardware acceleration than Xen. Xen requires a modified guest, which traps back to the host more frequently.

Is that true with the newer modes? https://wiki.xen.org/wiki/Understanding_the_Virtualization_S...

This is based on a cursory examination of [1], so I may be off-base. But Xen appears to rely on the host for many things that can be, and often are, hardware accelerated in KVM. Searching for CONFIG_XEN_PVHVM, it doesn't appear to cover much.

[1] https://github.com/torvalds/linux/blob/master/arch/x86/xen/

Reply on news.ycombinator.com