[ovs-dev] Drop in Rx rate if host kernel is only loaded with openvswitch.ko kernel module.

[Jesse Gross]

On Mon, Sep 28, 2015 at 8:52 AM,  <ravulakollu.kumar at wipro.com> wrote:
> Hello Team,
>
> Recently I observed  an issue which is very strange to me . I am testing  Phy-OVS-phy performance Testing(1G)
>
> I am using ovs-2.4.0 code. I compiled it successfully , and installed all userspace utils. And I insmoded
> openvswitch.ko kernel module only , nothing else(I could see other modules like vport-geneve.ko  vport-gre.ko  vport-lisp.ko etc.)
>
> Below is my configuration:
>
> 1.       Created a bridge and added two physical ports.(two are trunk ports)
>
> 2.       Started running vswitchd.
>
>
> Started pumping traffic(64byte packet at 1G rate) from external packet generator to phy port1 and receiving the same on packet
> on phy port2 (packet gen -phy1---OVS-phy2---packetgen) .
>
> But the results are very strange. Tx rate =761,904,776bps Rx rate=141,857,472bps. It's a huge drop in rx rate.
>
> Somehow I figured out that " I am inserting only openvswitch.ko" , which is the cause for huge decrease in rate.
>
> If I do modprobe openvswitch , I could see other modules (vxlan,gre) are loaded . In that case I am getting almost 1G Rx rate.
>
> Could someone tell me , why it's happening so?  Does these other modules are required for proper throughput ? correct me if my
> Analysis is wrong .

These modules shouldn't be needed unless you are using one of these
tunneling protocols (in which case traffic wouldn't flow at all
without them inserted). Assuming nothing else changed besides the
modules, I guess you are seeing some variations in your test setup.