+=head1 COLUMN HEADINGS
+
+=over 4
+
+=item B<%CPU>
+
+Percentage of CPU used. As with L<top(1)>, 100% means that
+all physical CPUs are being fully used.
+
+=item B<DEVICE>
+
+The block device name.
+
+=item B<DOMAIN>
+
+=item B<NAME>
+
+The name of the libvirt domain.
+
+=item B<ID>
+
+The libvirt domain ID.
+
+=item B<INTERFACE>
+
+The network interface name.
+
+=item B<%MEM>
+
+The percentage of host memory assigned to the guest.
+
+=item B<PHYCPU>
+
+The physical CPU.
+
+=item B<RDBY>
+
+Disk bytes read since last displayed.
+
+=item B<RDRQ>
+
+Disk read requests since last displayed.
+
+=item B<RXBY>
+
+Network bytes received since last displayed.
+
+=item B<RXPK>
+
+Network packets received since last displayed.
+
+=item B<S>
+
+The state of the domain, one of:
+
+=over 4
+
+=item B<?>
+
+Unknown.
+
+=item B<R>
+
+Running.
+
+=item B<S>
+
+Blocked.
+
+=item B<P>
+
+Paused.
+
+=item B<D>
+
+=item B<O>
+
+Shutdown.
+
+=item B<X>
+
+Crashed.
+
+=back
+
+=item B<TIME>
+
+Total CPU time used.
+
+=item B<TXBY>
+
+Network bytes transmitted since last displayed.
+
+=item B<TXPK>
+
+Network packets transmitted since last displayed.
+
+=item B<WRBY>
+
+Disk bytes written since last displayed.
+
+=item B<WRRQ>
+
+Disk write requests since last displayed.
+
+=back
+
+=head1 NOTES
+
+=head2 Block I/O statistics
+
+This I/O value is the amount of I/O since the previous iteration
+of virt-top. To calculate speed of I/O, you should divide
+the number by delay secs.
+
+=head2 NETWORK RX BYTES AND PACKETS
+
+Libvirt/virt-top has no way to know that a packet transmitted to a
+guest was received (eg. if the guest is not listening). In the
+network RX stats, virt-top reports the packets transmitted to the
+guest, on the basis that the guest might receive them.
+
+In particular this includes broadcast packets. Because of the way
+that Linux bridges work, if the guest is connected to a bridge, it
+will probably see a steady "background noise" of RX packets even when
+the network interface is idle or down. These are caused by STP
+packets generated by the bridge.
+
+=head2 DEBUGGING LIBVIRT ISSUES
+
+virt-top tries to turn libvirt errors into informative messages.
+However if libvirt initialization fails then this is not possible.
+Instead you will get an obscure error like:
+
+ libvir: error : Unknown failure
+ Fatal error: exception Libvirt.Virterror(...)
+
+To see the cause of libvirt errors in more detail, enable libvirt
+debugging by setting this environment variable:
+
+ export LIBVIRT_DEBUG=1
+