Re: [dpdk-dev] [PATCH v3 6/8] net/ice: support Rx AVX2 vector

["Lu, Wenzhuo" <wenzhuo.lu@intel.com>]

Hi Ferruh,


> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Thursday, March 21, 2019 1:37 AM
> To: Lu, Wenzhuo <wenzhuo.lu@intel.com>; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 6/8] net/ice: support Rx AVX2 vector
> 
> On 3/18/2019 1:37 AM, Lu, Wenzhuo wrote:
> > Hi Ferruh,
> >
> >
> >> -----Original Message-----
> >> From: Yigit, Ferruh
> >> Sent: Saturday, March 16, 2019 1:54 AM
> >> To: Lu, Wenzhuo <wenzhuo.lu@intel.com>; dev@dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH v3 6/8] net/ice: support Rx AVX2
> >> vector
> >>
> >> On 3/15/2019 6:22 AM, Wenzhuo Lu wrote:
> >>> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
> >> <...>
> >>
> >>> +#ifdef RTE_LIBRTE_ICE_16BYTE_RX_DESC
> >>> +		/* for AVX we need alignment otherwise loads are not
> >> atomic */
> >>> +		if (avx_aligned) {
> >>> +			/* load in descriptors, 2 at a time, in reverse order */
> >>> +			raw_desc6_7 = _mm256_load_si256((void *)(rxdp +
> >> 6));
> >>> +			rte_compiler_barrier();
> >>> +			raw_desc4_5 = _mm256_load_si256((void *)(rxdp +
> >> 4));
> >>> +			rte_compiler_barrier();
> >>> +			raw_desc2_3 = _mm256_load_si256((void *)(rxdp +
> >> 2));
> >>> +			rte_compiler_barrier();
> >>> +			raw_desc0_1 = _mm256_load_si256((void *)(rxdp +
> >> 0));
> >>> +		} else
> >>> +#endif
> >>> +		do {
> >>> +			const __m128i raw_desc7 =
> >>> +				_mm_load_si128((void *)(rxdp + 7));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc6 =
> >>> +				_mm_load_si128((void *)(rxdp + 6));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc5 =
> >>> +				_mm_load_si128((void *)(rxdp + 5));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc4 =
> >>> +				_mm_load_si128((void *)(rxdp + 4));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc3 =
> >>> +				_mm_load_si128((void *)(rxdp + 3));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc2 =
> >>> +				_mm_load_si128((void *)(rxdp + 2));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc1 =
> >>> +				_mm_load_si128((void *)(rxdp + 1));
> >>> +			rte_compiler_barrier();
> >>> +			const __m128i raw_desc0 =
> >>> +				_mm_load_si128((void *)(rxdp + 0));
> >>> +
> >>> +			raw_desc6_7 =
> >>> +				_mm256_inserti128_si256
> >>> +
> >> 	(_mm256_castsi128_si256(raw_desc6),
> >>> +					 raw_desc7, 1);
> >>> +			raw_desc4_5 =
> >>> +				_mm256_inserti128_si256
> >>> +
> >> 	(_mm256_castsi128_si256(raw_desc4),
> >>> +					 raw_desc5, 1);
> >>> +			raw_desc2_3 =
> >>> +				_mm256_inserti128_si256
> >>> +
> >> 	(_mm256_castsi128_si256(raw_desc2),
> >>> +					 raw_desc3, 1);
> >>> +			raw_desc0_1 =
> >>> +				_mm256_inserti128_si256
> >>> +
> >> 	(_mm256_castsi128_si256(raw_desc0),
> >>> +					 raw_desc1, 1);
> >>> +		} while (0);
> >>
> >> Is this to provide the proper indention because of the above #ifdef
> >> block? If so why not simple { } for the scope, is do{ }while(0) has benefit
> against it?
> > Yes, it's for the indention. To my opinion, "do while" looks friendly
> > to the readers as we always use it in the macros. Only "{}" looks
> > missing a function name or a "for ()" :)
> >
> 
> I found '{ }' more clear but no strong opinion, perhaps a comment to clarify
> to intention can be good but that also looks like optional, so up to you.
OK. I'll use '{}'. It also looks good to me.