[dpdk-dev] [RFC PATCH 0/4] ethdev new offloads API

[Shahaf Shuler]

Hi,

I would like to get some inputs on the below. 
This is a big (and important) work which I want to include on 17.11. I need to understand the current approach is acceptable before I continue.


Monday, August 7, 2017 1:54 PM, Shahaf Shuler:
> Tx offloads configuration is per queue. Tx offloads are enabled by default,
> and can be disabled using ETH_TXQ_FLAGS_NO* flags.
> This behaviour is not consistent with the Rx side where the Rx offloads
> configuration is per port. Rx offloads are disabled by default and enabled
> according to bit field in rte_eth_rxmode structure.
> 
> Moreover, considering more Tx and Rx offloads will be added over time, the
> cost of managing them all inside the PMD will be tremendous, as the PMD
> will need to check the matching for the entire offload set for each mbuf it
> handles.
> In addition, on the current approach each Rx offload added breaks the ABI
> compatibility as it requires to add entries to existing bit-fields.
> 
> The RFC address above issues by defining a new offloads API.
> With the new API, Tx and Rx offloads configuration is per queue.
> The offloads are disabled by default. Each offload can be enabled or disabled
> using the existing DEV_TX_OFFLOADS_* or DEV_RX_OFFLOADS_* flags.
> Such API will enable to easily add or remove offloads, without breaking the
> ABI compatibility.
> 
> The new API does not have an equivalent for the below Tx flags:
> 
> * ETH_TXQ_FLAGS_NOREFCOUNT
> * ETH_TXQ_FLAGS_NOMULTMEMP
> 
> The reason is that those flags are not to manage offloads, rather some
> guarantee from application on the way it uses mbufs, therefore could not be
> present as part of DEV_TX_OFFLOADS_*.
> Such flags are useful only for benchmarks, and therefore provide a non-
> realistic
> performance for DPDK customers using simple benchmarks for evaluation.
> Leveraging the work being done in this series to clean up those flags.
> 
> In order to provide a smooth transition between the APIs the following
> actions were taken:
> *  The old offloads API is kept for the meanwhile.
> *  New capabilities were added for PMD to advertize it has moved to the
> new
>    offloads API.
> *  Helper function which copy from old to new API and vice versa were
> added to ethdev,
>    enabling the PMD to support only one of the APIs, and the application to
> move to
>    the new API regardless the underlying device and without extra branching.
> 



> Shahaf Shuler (4):
>   ethdev: rename Rx and Tx configuration structs
>   ethdev: introduce Rx queue offloads API
>   ethdev: introduce Tx queue offloads API
>   ethdev: add helpers to move to the new offloads API
> 
>  lib/librte_ether/rte_ethdev.c | 144
> ++++++++++++++++++++++++++++++++++++-
>  lib/librte_ether/rte_ethdev.h |  72 +++++++++++++++----
>  2 files changed, 202 insertions(+), 14 deletions(-)
> 
> --
> 2.12.0