Get memory stats for a running domain.
-Depending on the hypervisor a variety of statistics can be returned
+Availability of these fields depends on hypervisor. Unsupported fields are
+missing from the output. Other fields may appear if communicating with a newer
+version of libvirtd.
+
+B<Explanation of fields>:
+ swap_in - The amount of data read from swap space (in kB)
+ swap_out - The amount of memory written out to swap space (in kB)
+ major_fault - The number of page faults where disk IO was required
+ minor_fault - The number of other page faults
+ unused - The amount of memory left unused by the system (in kB)
+ available - The amount of usable memory as seen by the domain (in kB)
+ actual - Current balloon value (in KB)
+ rss - Resident Set Size of the running domain's process (in kB)
For QEMU/KVM with a memory balloon, setting the optional I<--period> to a
value larger than 0 in seconds will allow the balloon driver to return