Re: [dpdk-dev] [PATCH v2 1/9] net/hns3: support runtime config to select IO burst func

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/10/2021 6:16 AM, Min Hu (Connor) wrote:
> From: Chengwen Feng <fengchengwen@huawei.com>
> 
> Currently, the driver support multiple IO burst function and auto
> selection of the most appropriate function based on offload
> configuration.
> 
> Most applications such as l2fwd/l3fwd don't provide the means to
> change offload configuration, so it will use the auto selection's io
> burst function.
> 
> This patch support runtime config to select io burst function, which
> add two config: rx_func_hint and tx_func_hint, both could assign
> vec/sve/simple/common.
> 
> The driver will use the following rules to select io burst func:
> a. if hint equal vec and meet the vec Rx/Tx usage condition then use
> the neon function.
> b. if hint equal sve and meet the sve Rx/Tx usage condition then use
> the sve function.
> c. if hint equal simple and meet the simple Rx/Tx usage condition then
> use the simple function.
> d. if hint equal common then use the common function.
> e. if hint not set then:
> e.1. if meet the vec Rx/Tx usage condition then use the neon function.
> e.2. if meet the simple Rx/Tx usage condition then use the simple
> function.
> e.3. else use the common function.
> 
> Note: the sve Rx/Tx usage condition based on the vec Rx/Tx usage
> condition and runtime environment (which must support SVE).
> 
> In the previous versions, driver will preferred use the sve function
> when meet the sve Rx/Tx usage condition, but in this case driver could
> get better performance if use the neon function.
> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> ---
>   doc/guides/rel_notes/release_21_05.rst |  1 +
>   drivers/net/hns3/hns3_ethdev.c         | 74 ++++++++++++++++++++++++++++++++++
>   drivers/net/hns3/hns3_ethdev.h         | 12 ++++++
>   drivers/net/hns3/hns3_ethdev_vf.c      |  1 +
>   drivers/net/hns3/hns3_rxtx.c           | 54 ++++++++++++++++++-------
>   5 files changed, 128 insertions(+), 14 deletions(-)
> 

Hi Connor,

There are two recently added APIs to enable user to select vector datapath:
'rte_vect_set_max_simd_bitwidth()'
'rte_vect_get_max_simd_bitwidth()'

Also there is an eal parameter around those APIs: '--force-max-simd-bitwidth'

I wonder these existing APIs can be utilized to select the vector path instead 
of adding device args to the PMD, can you please check?

Thanks,
ferruh