[ovs-discuss] Query regarding OVS configuration in OpenSuse Dom0 (Xen Hypervisor)

Mohit Dhingra mohitdhingras at gmail.com
Sun Feb 12 10:18:57 PST 2012

*Hi Jesse,*

Yes, I see your point that there is no benefit of controlling incoming
traffic, because anyways all traffic will arrive atleast till OVS level
from physical NIC, so that channel will be the bottleneck anyway.

I configured OVS using Xen as Hypervisor, and, I am able to create VMs
which automatically gets connected to the bridge that OVS created. But I am
not seeing any QoS control in the VM.

Here is the bridges and interfaces,
cadlab:~ # brctl show
bridge name     bridge id               STP enabled     interfaces
eth0            0000.7071bc62737a       no                peth0



I configured QoS on one of the VMs like this:
cadlab:~ # ovs-vsctl set Interface vif8.0 ingress_policing_rate=1000
cadlab:~ # ovs-vsctl set Interface vif8.0 ingress_policing_burst=100

VMs are as follows :
cadlab:~ # xm list
Name                                        ID   Mem VCPUs      State
Domain-0                                     0  6012     8     r-----
opensuse11                                   8  1024     1     -b----
opensuse11-clone                             6  1024     1     -b----

Then I ran netperf test, I don't see max of 1 Mbps !!!
vm1 at linux-g9jl:~> netperf -H
TCP STREAM TEST from ( port 0 AF_INET to
( port 0 AF_INET : demo
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

 87380  16384  16384    10.02      93.46

I see 93 Mbps !!! Why is it so?

Does anybody can tell me where I am wrong?

Thanks & Regards
Mohit Dhingra

On 9 February 2012 22:31, Jesse Gross <jesse at nicira.com> wrote:

> On Wed, Feb 8, 2012 at 11:24 PM, Mohit Dhingra <mohitdhingras at gmail.com>
> wrote:
> > The question that I was asking regarding monitoring of incoming traffic
> into
> > VMs is, we have one ingress_policing_rate in ovs_vsctl for an interface,
> but
> > there is no egress/outgress policing rate.. Does that mean that it
> doesn't
> > have control over incoming traffic onto VMs?
> Egress queuing is possible (and is the most common use case when
> applied to a physical interface) - look at the QoS section of the
> ovs-vsctl man page.  However, it's unlikely to be particularly useful
> when applied to VMs.  It won't reduce link usage at all because the
> traffic has already arrived and it's unlikely to reduce CPU usage very
> much single QoS is expensive to perform.
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