[dpdk-dev] [PATCH v2] doc: announce changes to ethdev rxconf structure

[Andrew Rybchenko]

On 8/5/20 11:49 AM, Viacheslav Ovsiienko wrote:
> The DPDK datapath in the transmit direction is very flexible.
> The applications can build multi-segment packets and manages
> almost all data aspects - the memory pools where segments
> are allocated from, the segment lengths, the memory attributes
> like external, registered, etc.
> 
> In the receiving direction, the datapath is much less flexible,
> the applications can only specify the memory pool to configure
> the receiving queue and nothing more. The packet being received
> can only be pushed to the chain of the mbufs of the same data
> buffer size and allocated from the same pool. In order to extend
> the receiving datapath buffer description it is proposed to add
> the new fields into rte_eth_rxconf structure:
> 
> struct rte_eth_rxconf {
>     ...
>     uint16_t rx_split_num; /* number of segments to split */
>     uint16_t *rx_split_len; /* array of segment lengths */
>     struct rte_mempool **mp; /* array of segment memory pools */
>     ...
> };
> 
> The non-zero value of rx_split_num field configures the receiving
> queue to split ingress packets into multiple segments to the mbufs
> allocated from various memory pools according to the specified
> lengths. The zero value of rx_split_num field provides the
> backward compatibility and queue should be configured in a regular
> way (with single/multiple mbufs of the same data buffer length
> allocated from the single memory pool).
> 
> The new approach would allow splitting the ingress packets into
> multiple parts pushed to the memory with different attributes.
> For example, the packet headers can be pushed to the embedded data
> buffers within mbufs and the application data into the external
> buffers attached to mbufs allocated from the different memory
> pools. The memory attributes for the split parts may differ
> either - for example the application data may be pushed into
> the external memory located on the dedicated physical device,
> say GPU or NVMe. This would improve the DPDK receiving datapath
> flexibility preserving compatibility with existing API.
> 
> The proposed extended description of receiving buffers might be
> considered by other vendors to be involved into similar features
> support, it is the subject for the further discussion.
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
> Acked-by: Jerin Jacob <jerinjacobk at gmail.com>

I"m OK with the idea in general and we'll work on details
in the next release cycle.

Acked-by: Andrew Rybchenko <arybchenko at solarflare.com>