Re: [dpdk-dev] Q on IXGBE and I40E vector Tx processing

[Ravi Kerur <rkerur@gmail.com>]

Hi Konstantin,

On Sun, Apr 16, 2017 at 3:26 PM, Ananyev, Konstantin <
konstantin.ananyev@intel.com> wrote:

>
> Hi Ravi,
>
> >
> > Hi,
> >
> > The reason I am asking I because I have tried different combinations of
> > scalar and vector Tx and Rx processing for both IXGBE and I40E with
> > following results
> >
> > 1. Vector Rx and Vector Tx gives best performance but can only support
> > packet size of less than or equal to 2048 bytes
> >
> > 2. Scalar Rx and Scalar Tx works for all packet size but with degraded
> > performance
> >
> > 3. Vector Rx and Scalar Tx (with certain PMD configuration) works fine
> > (performance doesn't meet '1') but it has an inherent bug for packet size
> > 8192 bytes as PMD stops packet processing
> >
> > From the code I see both IXGBE and I40E can support scattered vector Rx,
> I
> > am curious to know any obvious reasons scattered vector Tx support is
> left
> > out and does it make sense to implement it?
> >
> > If it makes sense to implement scattered vector Tx and Intel team hasn't
> > worked on it I would like to make an attempt at it so kindly let me know.
> >
>
> Yes, right now there is a tradeoff - simple TX functions (both vector and
> scalar) are much
> faster than full-featured TX function, but don't support any TX offloads
> or multi-segs.
> If you'd like to provide a patch that would add  some TX offloads to the
> simple path
> without any performance degradation or either a patch that would improve
> performance
> of full-featured TX function - I am pretty sure such patches would be
> welcomed.
>

Let me work on it and get back to you for any questions for clarifications.

Thanks,


> Konstantin
>
>
>