Hi Maxime, 

> > This version of the patch seems to have negative impact on performance
> for burst traffic profile[1].
> > Benefits seen with the previous version (v2) was up to ~1.6x for 1568 byte
> packets compared to ~1.2x seen with the current design (v3) as measured on
> new Intel hardware that supports DSA [2] , CPU @ 1.8Ghz.
> > The cause of the drop seems to be because of the excessive vhost txq
> contention across the PMD threads.
> 
> So it means the Tx/Rx queue pairs aren't consumed by the same PMD
> thread. can you confirm?

Yes, the completion polls for a given txq happens on a single PMD thread(on the 
same thread where its corresponding rxq is being polled) but other threads can 
submit(enqueue) packets on the same txq,  which leads to contention.

> 
> > [1]:
> > https://builders.intel.com/docs/networkbuilders/open-vswitch-optimized
> > -deployment-benchmark-technology-guide.pdf
> > [2]:
> > https://01.org/blogs/2019/introducing-intel-data-streaming-accelerator
> >
> > Thanks and regards
> > Sunil

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