[dpdk-dev] [PATCH v2 0/2] AVX2 Vectorized Rx/Tx functions for i40e

John Fastabend john.fastabend at gmail.com
Tue Jan 9 17:30:31 CET 2018


On 01/09/2018 06:32 AM, Bruce Richardson wrote:
> This patch adds an AVX2 vectorized path to the i40e driver, based on the
> existing SSE4.2 version. Using AVX2 instructions gives better performance
> than the SSE version, though the percentage increase depends on the exact
> settings used. For example:
> 

Hi Bruce,

Just curious, can you provide some hints on percent increase in at least
some representative cases? I'm just trying to get a sense of if this is
%5, 10%, 20%, more... I know mileage will vary depending on system, setup,
configuration, etc.

Thanks,
John

> * Using 16B rather than 32B descriptors gives the biggest benefit since
>   2 descriptors at a time can be read, rather than just 1 when 32B ones
>   are used.
> * Bigger burst sizes for RX gives improved performance - while we see an
>   improvement with testpmd with the default burst size of 32, burst sizes
>   of up to 128 give further improvements
> * In my testing, most of the improvement comes from faster processing on
>   the RX path, though the improved TX also gives benefit.
> 
> This has been tested on a system with CPU: "Intel(R) Xeon(R) Gold 6154 CPU
> @ 3.00GHz", and I've focused on testing with Rx ring sizes of approx 1k -
> generally --rxd=1024 and --txd=512, rather than the defaults which tend to
> give poorer zero-loss performance due to the smaller amount of buffering.
> 
> V2:
> * Fixed incorrect config variable reference in makefile
> * Added missing stub function for when vector drivers are disabled
> * Added missing references to the new functions when checking for vector
>   code paths, e.g. for ring tear-down
> 
> Bruce Richardson (2):
>   net/i40e: add AVX2 Tx function
>   net/i40e: add AVX2 Rx function
> 
>  drivers/net/i40e/Makefile             |  19 +
>  drivers/net/i40e/i40e_rxtx.c          |  66 ++-
>  drivers/net/i40e/i40e_rxtx.h          |   6 +
>  drivers/net/i40e/i40e_rxtx_vec_avx2.c | 792 ++++++++++++++++++++++++++++++++++
>  4 files changed, 880 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/net/i40e/i40e_rxtx_vec_avx2.c
> 



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