Sometimes a virtual machine inside kvm/qemu is saturated (load too high). Even a login (ssh) takes several seconds.
But the host is still accessible. How can I investigate why the virtual machine is saturated?
I would like to use top/iotop from outside. I would like to kill just those processes inside the vm which make trouble.
You cannot affect the VM directly from the host, however, commands like kvm_stat and top can provide a good view of what the VM is doing and where the bottleneck is. Under virsh (or in qemu-monitor) there are additional stats, like domblkstat for example
If your VM is so saturated you cannot access it's SSH console, you can try for a direct qemu console instead, using VNC/Spice or a serial console.
