I am developing a scheduler for running VMs on KVM. The scheduling has over-commitment of resources like memory and CPU. For this, I need a CLI-based monitoring tool that keeps me giving information about the resource usage of each VM, because it might be the case that due to over-provisioning of resources, VMs on a particular host are running very slowly depending on the benchmarks/programs each VM is running, and then I need to migrate a VM to another host and so on.

I looked into libvirt-based tools like collects, MUNIN, Nagios-vert, etc.( http://libvirt.org/apps.html#monitoring ) I also looked into Ubuntu utility perf-kvm ( http://manpages.ubuntu.com/manpages/maverick/man1/perf-kvm.1.html )

I want to ask which CLI-based would be recommended by the community so that I can make a automated scheduler that takes care of the above situation.