[dpdk-dev] [PATCH v2] doc: add new field to rxq info struct

[Ferruh Yigit]

On 8/6/2020 5:00 AM, Chengchang Tang wrote:
> Struct rte_eth_rxq_info will be modified to include a new field, indicating
> the size of each buffer that could be used for hw to receive packets. Add
> this field to rte_eth_rxq_info to expose relevant information to upper
> layer users/application.
> 
> For more details:
> https://mails.dpdk.org/archives/dev/2020-July/176135.html
> 
> Signed-off-by: Chengchang Tang <tangchengchang at huawei.com>
> Acked-by: Andrew Rybchenko <arybchenko at solarflare.com>
> ---
>  doc/guides/rel_notes/deprecation.rst | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index ea4cfa7..f08b5f9 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -110,6 +110,15 @@ Deprecation Notices
>    break the ABI checks, that is why change is planned for 20.11.
>    The list of internal APIs are mainly ones listed in ``rte_ethdev_driver.h``.
>  
> +* ethdev: A new field will be added to the public data structure
> +  ``rte_eth_rxq_info`` to indicate the buffer size used in receiving packets
> +  for HW. When receive packets, HW DMA won't exceed this size.

Overall +1 to provide this information.

This field is only to report back the PMD configured Rx buffer size, it won't
affect the configuration step, do you think should we highlight this?

Also will this field be optional or mandatory, this matters for the scope of the
work for 20.11. I think the intention is to provide an optional field, what do
you think to documenting that it is optional?

> And it will
> +  affect the number of fragments in receiving packets when scatter is enabled.

Is this detail required in the deprecation notice? I see it is relevant but
the configured Rx buffer size affects the number of the fragments, but reporting
this value does not.
Do you want to mention above as motivation to have the field? If so I don't
expect application to calculate the number of the fragments using this value.
I am for dropping above sentences if I am not missing anything.

> +  So, add this field to ``rte_eth_rxq_info`` to expose relevant information to
> +  upper layer user/application.

And not sure above sentences says anything new, looks like duplication to me.

> +  This change is planned for 20.11. For more details:
> +  https://mails.dpdk.org/archives/dev/2020-July/176135.html
> +
>  * traffic manager: All traffic manager API's in ``rte_tm.h`` were mistakenly made
>    ABI stable in the v19.11 release. The TM maintainer and other contributors have
>    agreed to keep the TM APIs as experimental in expectation of additional spec
>