10 Apr
2013
10 Apr
'13
2:45 p.m.
does libvirt make a user pay penalty, even if only a small amount, for using it when compared to raw qemu-kvm command line?
Not that I know of, except that the libvirt daemon uses a few additional CPU cycles. Technically yes, in the spirit of the question no. Have a look at your process tree; you'll see command lines in the same way as you'd expect them to be when you start machines manually.
if it does where the overhead goes? quest or host, or maybe both?
No additional CPU cycles for the guest, a few additional CPU cycles for the host to get status information and expose it via the daemon.
if overall performance is slower then how small it is comparing to all the advantages it offers?
It is completely negligible. Felicitus