[dpdk-dev] [PATCH] net/iavf: fix performance drop

Zhang, Qi Z qi.z.zhang at intel.com
Tue Apr 27 04:57:20 CEST 2021



> -----Original Message-----
> From: Lu, Wenzhuo <wenzhuo.lu at intel.com>
> Sent: 2021年4月27日 9:51
> To: Zhang, Qi Z <qi.z.zhang at intel.com>; dev at dpdk.org
> Subject: RE: [dpdk-dev] [PATCH] net/iavf: fix performance drop
> 
> > > +use_sse = true;
> > > +if ((rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX2) == 1 ||
> > > +     rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX512F) == 1) &&
> > > +    rte_vect_get_max_simd_bitwidth() >= RTE_VECT_SIMD_256)
> > > +use_avx2 = true;
> >
> >
> > Not sure if the right path will be selected when avx512 is not true,
> > (CC_AVX512_SUPPORT is disable) while check_ret is
> > IAVF_VECTOR_OFFLOAD_PATH?
> >
> > Currently we have
> >
> > if (!use_sse && !use_avx2 && !use_avx512) goto normal;
> >
> > Should we also add below check?
> >
> > if (!use_avx512 && check_ret == IAVF_VECTOR_OFFLOAD_PATH)
> >    goto normal;
> Not necessary. As explained in the commit log, AVX2 and SSE support the
> offload features. The purpose of this patch is to let AVX2 be chosen when
> offload needed and AVX512 disable.

OK, now I understand it, I will suggest to change the commit log.

From 
AVX2 and SSE don't have the offload path.

To 
AVX2 and SSE Tx path already support offloads but can't selected.

If you agree, will apply above during change during patch merge.



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