Using the KVM API

I set up a system locally to run programs under a VM in qemu-kvm with shared folders and it was insanely slow, especially git and find. Stracing on the host showed that for each stat() in the guest, the host was doing a stat() on each directory component. So a stat() of a complete directory tree went O(N^2) on the directory depth.

Now, I get that it's probably a configuration issue since it clearly wasn't caching anything, but I found it really hard to find documentation about qemu that explained this behaviour. On top of that I'm managing them via libvirt, so even if I find a command-line option to deal with something, if libvirt doesn't support it I'm still SOL.

Overall, it hasn't been a great experience, next time I'll probably do what other people do, use VirtualBox or VMWare.

But back to the article, it's a pretty nice interface actually. Hopefully I'll find some reason to use it sometime :)