Hi Martin, Thanks for your reply. Please correct me if I am wrong here. The latest version of libvirt generates the following flags with respect to memory a) swap_in b) swap_out c) major_fault d) minor_fault e) unused f) available g) actual_balloon h) rss I assumed that the "unused" flag represents the memory that is not consumed / not used by the virtual machine. In order to calculate the memory that is used by the VM / KVM process associated with the VM, I thought I should subtract the available or set memory - unused memory. Regards, Krishnaprasad -----Original Message----- From: Martin Kletzander [mailto:mkletzan@redhat.com] Sent: Freitag, 2. Januar 2015 16:15 To: Narayanan, Krishnaprasad Cc: libvir-list(a)redhat.com Subject: Re: [libvirt] libvirt memory flags On Wed, Dec 31, 2014 at 01:36:21AM +0000, Narayanan, Krishnaprasad wrote: It's hard to define what you mean by "unused" memory. The API you are talking about returns (at least for the QEMU driver) memory information about the process itself. These are, of course, different values than he amount of memory inside the VM. If you want to know what is the current memory amount set for the VM, you can find it in the XML output of 'virsh dumpxml <domain>'. Further data should be available from guest agent, but libvirt does not have an API for this. You can, however, query that information using an arbitrary guest agent command (virsh qemu-agent-command), but I'm not sure about that and neither about the commands. Martin