[ovs-dev] OVS and macvtap - statistics

K.R.Kishore krkishore at yahoo.com
Sat Jun 8 03:52:18 UTC 2013

Hi Jesse
Thanks for responding. 

I checked this earlier and it does not add up. I looked at the delta before and after I ran the netperf test for 10s on a 10G link ( I get ~6G with my current parameters). The ifconfig numbers are in the ballpark for 10s of transmission at ~6G, but the ovs-dpctl numbers are nowhere close.

Any other clues?

- Kishore

On Jun 7, 2013, at 5:56 PM, Jesse Gross <jesse at nicira.com> wrote:

> On Fri, Jun 7, 2013 at 11:46 AM, K.R Kishore <krkishore at yahoo.com> wrote:
>> Hi
>> I am trying to understand the statistics from ovs-dpctl and reconcile that
>> with stats from other tools. I am finding it difficult to make sense of the
>> numbers, perhaps someone can point me to some documentation about how this
>> works? There are numerous links on the web and it is quite confusing as I am
>> not sure which is authoritative.
>> My setup is as follows:
>> Two machines connected back-to-back via 10G NICs
>> Both machines running RHEL 6.4/ wKVM; Two VMs on each, both running CentOS
>> 6.4
>> OVS 1.10 installed on both;
>> Created bridge (ovsbr0) and connected the VMs via macvtap (bridge mode
>> -allegedly; VMM says bridge mode, but the host cannot VM and vice-versa; VMs
>> can communicate with external hosts/VMs)
>> I also have linux bridges (br0 & br1) on these VMs but they bridge the VMs
>> to different physical ports (p4p1 and em1)
>> Ran netperf (and netserver) between host1-vm1 and host2-vm1successfully; got
>> stats from neperf
>> I have attached the stats outputs from ovs-dpctl, ifconfig -a and  ip -s
>> link and I cannot reconcile these:
>> - The port numbers do not match across these, but I can ignore that for now
>> - The Rx packets and bytes from ovs-dpctl (port 2: p4p2) does not match (or
>> come close to) the ipconfig -a p4p2  or 'ip -s link' (for p4p2)
>> - The macvtap ports do show the traffic coming out of the VMs (I see the
>> increments in the same ballpark when I run netperf and observe through ip -s
>> link and ipconfig -a)
>> -
>> Is all traffic going through OVS bridge (ovsbr0)? Does ovs-dpctl count show
>> something? Do I need to enable statistics somewhere?
> OVS tracks packets that have flowed through the switch since the port
> was connected whereas the interface statistics show counts since boot.
> My guess is that accounts for the difference.

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