[ovs-dev] [PATCH] tunneling: Improving VxLAN tunneling performance using DPDK Rx checksum offloading feature.

Jesse Gross jesse at kernel.org
Mon Apr 11 16:32:40 UTC 2016


On Mon, Apr 11, 2016 at 2:52 AM, Sugesh Chandran
<sugesh.chandran at intel.com> wrote:
> Optimizing VxLAN tunneling performance in userspace datapath by offloading
> the rx checksum validation on tunnel packets to the NIC when it is supported.
>
> Signed-off-by: Sugesh Chandran <sugesh.chandran at intel.com>

Thanks for working on this. I think there is a lot of room for OVS
DPDK to take advantage of common NIC offloads.

I have some high level comments:

* I noticed that you've been following up you patches with a second
message with performance numbers. I think it would be better to just
include this in the patch description since that's what will become
the commit message. Even if the numbers might change over time, it's
useful to have a reference to what the expected performance benefit
was at the time the patch was authored. Related to this, it would also
be useful to have more context on the benchmark numbers that you are
providing. For example, I'm guessing that the test was run using VXLAN
with outer UDP checksums? What NIC was used?

* I think we need to have a clearer way to pass around checksum state
rather than as an argument, it's just too invasive. A natural place
that most OSs use is in metadata associate with the packet itself,
which would be struct dp_packet in this case. It's also important to
consider how this will be expanded over time. For example, offloading
of transmit checksums would likely want to use the same fields.

* Please find a way to do this without duplicating the tunnel header
extraction code. Having two copies will surely result in bugs over
time. Potentially the previous point may help with this.

* Please try to generalize your code where possible. In this case it
looks like IPv6, Geneve, and GRE (at least the IP checksum) could
easily be supported using the same mechanism.



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