[ovs-dev] [PATCH v2] tunneling: Improving tunneling performance using DPDK Rx checksum offloading feature.

[Chandran, Sugesh]

Regards
_Sugesh


> -----Original Message-----
> From: Jesse Gross [mailto:jesse at kernel.org]
> Sent: Wednesday, May 4, 2016 10:06 PM
> To: Chandran, Sugesh <sugesh.chandran at intel.com>
> Cc: pravin shelar <pshelar at ovn.org>; ovs dev <dev at openvswitch.org>
> Subject: Re: [ovs-dev] [PATCH v2] tunneling: Improving tunneling
> performance using DPDK Rx checksum offloading feature.
> 
> On Wed, May 4, 2016 at 8:58 AM, Chandran, Sugesh
> <sugesh.chandran at intel.com> wrote:
> >> -----Original Message-----
> >> From: Jesse Gross [mailto:jesse at kernel.org]
> >> Sent: Thursday, April 28, 2016 4:41 PM
> >> To: Chandran, Sugesh <sugesh.chandran at intel.com>
> >> Cc: pravin shelar <pshelar at ovn.org>; ovs dev <dev at openvswitch.org>
> >> Subject: Re: [ovs-dev] [PATCH v2] tunneling: Improving tunneling
> >> performance using DPDK Rx checksum offloading feature.
> >
> >> That sounds great, thanks for following up. In the meantime, do you
> >> have any plans for transmit side checksum offloading?
> > [Sugesh] The vectorization on Tx side is getting disabled when DPDK Tx
> checksum offload is enabled. This causes performance drop in OVS.
> > However We don’t find any such impact when enabling Rx checksum
> offloading(though this disables Rx vectorization).
> 
> OK, I see. Does the drop in throughput cause performance to go below the
> baseline even for UDP tunnels with checksum traffic? (I guess small and large
> packets might have different results here.) Or is it that it reduce performance
> for unrelated traffic? If it's the latter case, can we find a way to use offloading
> conditionally?
[Sugesh] We tested for 64 byte UDP packet stream and found that the performance 
is better when the offloading is turned off. This is for any traffic through the port. 
DPDK doesn’t support conditional offloading for now.
In other words DPDK can't do selective vector packet processing on a port.
As far as I know there are some technical difficulties to enable offload + vectorization together
in DPDK.