> -----Original Message-----
> From: dev <dev-boun...@dpdk.org> On Behalf Of Prashant Upadhyaya
> Sent: Sunday, May 10, 2020 22:06
> To: dev@dpdk.org
> Subject: [dpdk-dev] Regarding rte_eth_rx_burst
>
> Hi,
>
> I recently started using X722 NIC which uses i40 PMD of DPDK.
> I am on DPDK 20.02.
> I am seeing that when I call the rte_eth_rx_burst with last argument
> as 1 (polling for 1 mbuf), then I am not receiving data via repeated
> calls.
I saw this kind of issue many times. ;-)
This is *burst* for vector mode:
drivers/net/i40e/i40e_rxtx_vec_sse.c
static inline uint16_t
_recv_raw_pkts_vec(struct i40e_rx_queue *rxq, struct rte_mbuf **rx_pkts,
uint16_t nb_pkts, uint8_t *split_packet)
{
....
/* nb_pkts shall be less equal than RTE_I40E_MAX_RX_BURST */
nb_pkts = RTE_MIN(nb_pkts, RTE_I40E_MAX_RX_BURST);
/* nb_pkts has to be floor-aligned to RTE_I40E_DESCS_PER_LOOP */
nb_pkts = RTE_ALIGN_FLOOR(nb_pkts, RTE_I40E_DESCS_PER_LOOP); <---
nb_pkts = 0, if you passed 1.
> When I go for calls to rte_eth_rx_burst with last argument as 32, the
> function does return the mbuf's as received data.
>
> Is this expected ? Or this is a bug in the i40 driver handling this NIC ?
>
> The polls to rte_eth_rx_burst with last argument as 1 works well for
> the ixgbe PMD for sure since I have been using X520 successfully with
> last argument as 1.
>
> Regards
> -Prashant
