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.