Re: [dpdk-dev] [PATCH v2 6/6] net/ice: switch to Rx flexible descriptor in AVX path

["Rong, Leyi" <leyi.rong@intel.com>]

> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Friday, August 30, 2019 7:32 AM
> To: Rong, Leyi <leyi.rong@intel.com>; Ye, Xiaolong <xiaolong.ye@intel.com>;
> Wang, Haiyue <haiyue.wang@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>
> Cc: dev@dpdk.org
> Subject: RE: [PATCH v2 6/6] net/ice: switch to Rx flexible descriptor in AVX path
> 
> 
> >  		 * take the two sets of status bits and merge to one @@ -
> 450,20
> > +452,22 @@ _ice_recv_raw_pkts_vec_avx2(struct ice_rx_queue *rxq,
> > +struct
> > rte_mbuf **rx_pkts,
> >  		/* get only flag/error bits we want */
> >  		const __m256i flag_bits =
> >  			_mm256_and_si256(status0_7, flags_mask);
> > -		/* set vlan and rss flags */
> > -		const __m256i vlan_flags =
> > -			_mm256_shuffle_epi8(vlan_flags_shuf, flag_bits);
> > -		const __m256i rss_flags =
> > -			_mm256_shuffle_epi8(rss_flags_shuf,
> > -					    _mm256_srli_epi32(flag_bits, 11));
> >  		/**
> >  		 * l3_l4_error flags, shuffle, then shift to correct adjustment
> >  		 * of flags in flags_shuf, and finally mask out extra bits
> >  		 */
> >  		__m256i l3_l4_flags = _mm256_shuffle_epi8(l3_l4_flags_shuf,
> > -				_mm256_srli_epi32(flag_bits, 22));
> > +				_mm256_srli_epi32(flag_bits, 4));
> >  		l3_l4_flags = _mm256_slli_epi32(l3_l4_flags, 1);
> >  		l3_l4_flags = _mm256_and_si256(l3_l4_flags, cksum_mask);
> > +		/* set rss and vlan flags */
> > +		const __m256i rss_vlan_flag_bits =
> > +			_mm256_srli_epi32(flag_bits, 12);
> > +		const __m256i rss_flags =
> > +			_mm256_shuffle_epi8(rss_flags_shuf,
> rss_vlan_flag_bits);
> > +		const __m256i vlan_flags =
> > +			_mm256_shuffle_epi8(vlan_flags_shuf,
> > +					    rss_vlan_flag_bits);
> 
> Seems we can "or" rss_flags_shuf and vlan_flags_shuf, so just need to do one
> shuffle here to save some CPU cycles?
> 

That's make sense literally, will do some benchmarking test for this adjustment:).

> >
> >  		/* merge flags */
> >  		const __m256i mbuf_flags = _mm256_or_si256(l3_l4_flags,
> > --
> > 2.17.1