Ok. So that's why I was getting 1 GB as a result. So is there any way I can get memory in used programmatically? I mean without going inside guest domain. <div class="gmail_quote">On Aug 5, 2016 5:42 PM, "Andrea Bolognani" <<a href="mailto:abologna@redhat.com">abologna@redhat.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Thu, 2016-08-04 at 20:02 +0500, Aleem Akhtar wrote: > > I am trying to get stats of Domains running under XEN hypervisor. > I used Libvirt function for this purpose. I am trying to understand > output for Memory. Domain running is Fedora-22 with 1GB Ram. Here is my > code > > y = virDomainGetInfo(allDomain, &info); > if (y == -1) > printf("Errorl\n"); > else { > printf("Max Memory: %lu\n", info.maxMem); > printf("Memory: %lu", info.memory); > } > > I get output as > > Max Memory: 1048576 > Memory: 1048576 > > Now, as per Libvirt API, info.memory should return the memory in KBytes > used by the domain. My Question is, if info.memory returns memory used > and my domain is using complete 100% of Max Memory or not? Also I tried > to create Domain with memory varying from 128MB to 2GB with same effect. > I also tried to run some applications in Domain but Memory usage return > by given function does not change. Any help or guidance will be much > appreciated. The relevant virDomainInfo field is described as /* the memory in KBytes used by the domain */ unsigned long memory; but in this context, "used by" really means "available to". So the output above tells you that your Fedora guest has 1 GB of memory available; how much of that memory is actually being used by the guest OS is something that you can find out by running top inside the guest. -- Andrea Bolognani / Red Hat / Virtualization </blockquote></div>