[ovs-dev] [PATCH v9] netdev-dpdk: Enable Rx checksum offloading feature on DPDK physical ports.

[Pravin Shelar]

On Mon, Jan 2, 2017 at 2:27 PM, Sugesh Chandran
<sugesh.chandran at intel.com> wrote:
> Add Rx checksum offloading feature support on DPDK physical ports. By default,
> the Rx checksum offloading is enabled if NIC supports. However,
> the checksum offloading can be turned OFF either while adding a new DPDK
> physical port to OVS or at runtime.
>
> The rx checksum offloading can be turned off by setting the parameter to
> 'false'. For eg: To disable the rx checksum offloading when adding a port,
>
>      'ovs-vsctl add-port br0 dpdk0 -- \
>       set Interface dpdk0 type=dpdk options:rx-checksum-offload=false'
>
> OR (to disable at run time after port is being added to OVS)
>
>     'ovs-vsctl set Interface dpdk0 options:rx-checksum-offload=false'
>
> Similarly to turn ON rx checksum offloading at run time,
>     'ovs-vsctl set Interface dpdk0 options:rx-checksum-offload=true'
>
> The Tx checksum offloading support is not implemented due to the following
> reasons.
>
> 1) Checksum offloading and vectorization are mutually exclusive in DPDK poll
> mode driver. Vector packet processing is turned OFF when checksum offloading
> is enabled which causes significant performance drop at Tx side.
>
> 2) Normally, OVS generates checksum for tunnel packets in software at the
> 'tunnel push' operation, where the tunnel headers are created. However
> enabling Tx checksum offloading involves,
>
> *) Mark every packets for tx checksum offloading at 'tunnel_push' and
> recirculate.
> *) At the time of xmit, validate the same flag and instruct the NIC to do the
> checksum calculation.  In case NIC doesnt support Tx checksum offloading,
> the checksum calculation has to be done in software before sending out the
> packets.
>
> No significant performance improvement noticed with Tx checksum offloading
> due to the e overhead of additional validations + non vector packet processing.
> In some test scenarios, it introduces performance drop too.
>
> Rx checksum offloading still offers 8-9% of improvement on VxLAN tunneling
> decapsulation even though the SSE vector Rx function is disabled in DPDK poll
> mode driver.
>
> Signed-off-by: Sugesh Chandran <sugesh.chandran at intel.com>
> Acked-by: Jesse Gross <jesse at kernel.org>
> ---
> v9
> - Updated get-config to report rx-checksum-offload when configured.
> - Rebase to the OVS latest master
>
I fixed various build warnings and updated NEWS. and then pushed patch
to master.

Thanks.