[virt-tools-list] virt-top not showing disk and network usage

[Richard W.M. Jones]

On Fri, May 21, 2010 at 09:40:18PM -0500, Neil Aggarwal wrote:
> When I run virt-top, it shows me the CPU and memory
> usage of the VMs, but the disk and network colums
> are empty.
> 
> I found this page:
> http://people.redhat.com/~rjones/virt-top/faq.html
> 
> That states it depends on what is supported by
> libvirt and the hypervisor.

Basically you need to look at whether the stats are available in
libvirt.  For example on my (Fedora) host:

# virsh domifstat F13x64 vnet0
vnet0 rx_bytes 30105725
vnet0 rx_packets 31983
vnet0 rx_errs 0
vnet0 rx_drop 0
vnet0 tx_bytes 1252853
vnet0 tx_packets 13921
vnet0 tx_errs 0
vnet0 tx_drop 0

# virsh domblkstat F13x64 hda
hda rd_req 13545
hda rd_bytes 341982208
hda wr_req 9968
hda wr_bytes 206386176

I also tried this on a CentOS 5.4 machine, and I think there is a bug
in libvirt because I get some strangely inconsistent results from
these commands (as in, sometimes they run and sometimes they fail,
randomly AFAICT).

It's quite possible that the version of libvirt in RHEL 5 doesn't
fully support these stats, and I'm pretty sure we don't test network
and block stats (since we never provided or supported virt-top in RHEL
5, so we don't need it to).  RHEL 6 will ship with a fully supported
virt-top command.

Followups set to virt-tools-list.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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