Daniel Jitnah writes:
2. The main reason for KVM improvement would come from the virtio drivers for disk i/o. (Running an OS install with and without virtio enabled, will show the obvious difference) [...] 7. Virt-manager works well with both for what I have ever needed it to and keeps improving.
NB: when using kvm via virtd, you are only able to configure the parts that virtd wraps. For example, I'm not sure you can use -net user *at all*. OTOH virtd is more likely (than a newbie) to pick fast defaults :-) The exact options virtd uses to invoke qemu/kvm are logged in /var/log/libvirt/qemu/<name>.log (as at 1.2.4-1~bpo70+1). Here's an example, you can see it uses virtio heavily: LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin HOME=/root USER=root LOGNAME=root QEMU_AUDIO_DRV=none /usr/bin/kvm -name twb -S -machine pc-0.12,accel=kvm -m 1024 -smp 4,sockets=4,cores=1,threads=1 -uuid 1d43ba9c-1e95-dfaa-f38a-c5581ca14b3a -nographic -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/twb.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/srv/kvm/twb.img,if=none,id=drive-virtio-disk0,format=raw -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=23,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=06:00:00:00:34:69,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 PS: last time I looked, virt-manager GUI lagged behind the main project significantly, and was full of bugs. I can cheerfully recommend using virsh(8) instead.