Re: [PATCH v2] net/intel: deprecate some SSE paths

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Jul 18, 2025 at 04:03:17PM +0100, Kevin Traynor wrote:
> On 03/07/2025 15:31, Ciara Loftus wrote:
> > The SSE rx and tx paths will be removed from the i40e, iavf and ice
> > drivers in the 25.11 release. Each of these drivers have faster vector
> > paths (AVX2 and AVX-512) which have feature parity with the soon to be
> > removed SSE paths. In environments where AVX2 or AVX-512 are not
> > supported, the scalar path will still be used, which also has feature
> > parity.
> > 
> > Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> > ---
> >  doc/guides/rel_notes/deprecation.rst | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> > index e2d4125308..0d020c9c1f 100644
> > --- a/doc/guides/rel_notes/deprecation.rst
> > +++ b/doc/guides/rel_notes/deprecation.rst
> > @@ -80,6 +80,13 @@ Deprecation Notices
> >    and the header struct ``rte_vxlan_gpe_hdr`` with the macro ``RTE_ETHER_VXLAN_GPE_HLEN``
> >    will be removed in DPDK 25.11.
> >  
> > +* net/intel: drivers that have an SSE vector path alongside other vector paths,
> > +  namely i40e, iavf and ice, will have their SSE vector paths removed in DPDK 25.11.
> > +  Modern x86 systems all support AVX2, if not AVX-512, so the SSE path is no longer
> > +  widely used. This change will not result in any feature loss, as the fallback
> > +  scalar paths which have feature parity with SSE will be used in the cases where
> > +  the SSE paths would have been used.
> > +
> >  * ethdev: The flow API matching pattern structures, ``struct rte_flow_item_*``,
> >    should start with relevant protocol header structure from lib/net/.
> >    The individual protocol header fields and the protocol header struct
> 
> I'm not aware of anyone using hardware that old and relying on SSE, but
> it seems a bit short notice for a patch to remove hardware support.
> 
> Would it hurt much to give it a longer deprecation so anyone who needs
> to prepare by upgrade, or taking 25.11 with support etc. can do that ?
> 
Do we think that will make a difference? After all, dropping the SSE path
won't break DPDK on older hardware, it will only run a bit slower using the
scalar path. Beyond that, it would only affect deployments with new/latest
DPDK on old hardware - obviously old hardware running older DPDK would be
unaffected.

/Bruce