[dpdk-dev] Requirement of minimum Rx burst size for PMDs

[Yongseok Koh <yskoh@mellanox.com>]

Hi,

In some rx_burst functions, especially for vectorized ones (e.g. i40e_rxtx_vec*
or mlx5_rxtx_vec*), there's actually a requirement of min burst size.

As it manipulates 4 packets simultaneously in a loop, if nb_pkts of
rte_eth_rx_burst() is less than 4, it just returns without sending a packet.

One way to handle it could be falling back to regular rx_burst in such cases but
the burst size isn't a fixed/static parameter but applications can dynamically
change it when it polls a device. So, it might not be a good option.

Therefore, how about adding min_rx/tx_burst_sz in struct rte_eth_dev_info and
have PMDs fill it in on dev_ops->dev_infos_get() so as to make apps comply with
it.

Because the max size of a burst can be handled well by PMD, it may not be
necessary.

Thoughts?


Thanks,
Yongseok