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

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Yigit, Ferruh <ferruh.yigit@intel.com>
> Sent: Wednesday, April 28, 2021 7:32 PM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>; Lu, Wenzhuo
> <wenzhuo.lu@intel.com>; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] net/iavf: fix performance drop
> 
> On 4/27/2021 3:57 AM, Zhang, Qi Z wrote:
> >
> >
> >> -----Original Message-----
> >> From: Lu, Wenzhuo <wenzhuo.lu@intel.com>
> >> Sent: 2021年4月27日 9:51
> >> To: Zhang, Qi Z <qi.z.zhang@intel.com>; dev@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.
> >
> 
> Isn't this related to the _Rx_ path?

Yes, it should be Rx Path.

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