[ovs-discuss] Questions about Open vSwitch QoS

Henrique Rodrigues henriquesilvar at gmail.com
Wed Sep 15 04:41:59 UTC 2010


I have been studying OVS and I have some questions about its QoS.

I installed the Open vSwitch 1.1.0pre1 on a Xen machine hosting a single VM.
I followed the QoS Cookbook entry to limit the VM rate to 1Mbps. Through the
netperf test, I verified that the VM output rate is indeed 1Mbps.

Then, back to the Xen host, I noticed OVS had attached an ingress qdisc to
the VM interface (vif1.0). Does this means that running the commands from
the cookbook has the same results as running "tc qdisc add dev vif1.0
ingress" and rate limiting the ingress qdisc? What is the difference between
these two scenarios?

The other question is about whether OVS QoS supports borrowing the excess
bandwidth (as described in the htb user guide [1]) or not. From the
observations above, I think the answer is probably no, isn't it?
If so, is there any other way to have a max-min rate limiting with OVS?

Hope someone could help me with these questions.

[1] http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm

Henrique Rodrigues
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