KVM speed test

2019, Dec 16    

Some time ago I made a recursive speed test for testing nested KVM virtualization.

Using packer, we create a vagrant box, runs some speedtest, and spins up a nested VM using vagrant.

The repo is here.

(Unimpressive) stats from my test server

Test L0 (host) L1 L2
Disk (cached) 2771.96 MB/sec 2825.12 MB/sec 1833.57 MB/sec
Disk (buffered) 125.66 MB/sec 651.48 MB/sec 173.55 MB/sec
1GB SHA256 15.558 s 16.9574 s 31.5948 s

Something is odd with the buffered disk read on L0 and L3 is not included, since I got a vagrant timeout. On this hardware, it runs virtualmachines nicely, but it is not good for nested virtualization. I have seen hardware that handles multiple nesting much better - I think it is CPU+chipset related.

And when doing nesting, one should consider using network storage.