On Mon, Jun 29, 2015 at 1:04 PM, Rick Jones [off-list ref] wrote:

PS  FWIW, if I shift from using just the linux native vxlan to a "mostly
full" set of OpenStack compute node plumbing - two OVS bridges and a linux
bridge and associated plumbing with a vxlan tunnel defined in OVS, but
nothing above the Linux bridge (and no VMs) I see more like 4.9 Gbit/s.  The
veth pair connecting the linux bridge to the top ovs bridge show rx checksum
and gro enabled.  the linux bridge itself shows GRO but rx checksum off
(fixed).  I'm not sure how to go about checking the OVS constructs.

This is because the OVS path won't go through the VXLAN device receive
routines and the code from this patch won't be executed. Your results
make sense then because it is similar to the original no GRO case.

This should hopefully be resolved soon - there are some patches in
progress that will make OVS use the normal tunnel device receive
paths. Once those are in, the performance should be equal in both
cases.