[libvirt] libvirt to report cpuWait of a guest.

Hi, We are working on fixing CPU utilization calculation of guests (VMs) in Ceilometer metering service of OpenStack. Per that fix, we retrieve, at the host level, se.statistics.wait_sum (or se.wait_sum in old versions) Linux kernel schedstat counter of the KVM/QEMU threads ? that represent the VM. That counter denotes the time in milliseconds the thread 'wants' to run (but not actually running because of a contention). However, as Daniel Berrange mentioned in the fix review, it would be better to retrieve that information from libvirt instead and he asked me to raise this in this mailing list. I could not notice that libvirt exposes such a counter. It would be very good if virDomainInfo ( https://libvirt.org/html/libvirt-libvirt-domain.html#virDomainInfo) can be added with cpuWait in addition to cpuTime it currently has so that cpuWait will denote the total *time* the VM *wants* to run. Adding cpuWait to any other location of domain is fine as well. Thanks, Avi Weit