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What’s the benefit of KVM over Xen these days?
by nnx 9y ago
What’s the benefit of KVM over Xen these days?
- alpb 9y agoI am also curious. I found this article which might help a little bit: https://www.theregister.co.uk/2017/01/30/google_cloud_kicked_qemu_to_the_kerb_to_harden_kvm/ https://www.theregister.co.uk/2017/01/30/google_cloud_kicked...
- abdulla 9y agoKVM can take better advantage of hardware acceleration than Xen. Xen requires a modified guest, which traps back to the host more frequently.
- wmf 9y agoIs that true with the newer modes? https://wiki.xen.org/wiki/Understanding_the_Virtualization_Spectrum https://wiki.xen.org/wiki/Understanding_the_Virtualization_S...
- abdulla 9y agoThis 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/ https://github.com/torvalds/linux/blob/master/arch/x86/xen/
- _msw_ 9y agoIt'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.