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(-)

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2.12.0