[dpdk-users] Issue with mlx5_rxtx.c while calling rte_eth_tx_burst() in DPDK 18.11
Yongseok Koh
yskoh at mellanox.com
Wed Apr 24 01:45:55 CEST 2019
> On Apr 21, 2019, at 9:59 PM, Arvind Narayanan <webguru2688 at gmail.com> wrote:
>
> I am running into a weird problem when using rte_eth_tx_burst() using mlx5
> in dpdk 18.11, running on Ubuntu 18.04 LTS (using Mellanox Connect X5 100G
> EN).
>
> Here is a simplified snippet.
>
> ==================
> #define MAX_BATCHES 64
> #define MAX_BURST_SIZE 64
>
> struct batch {
> struct rte_mbuf *mbufs[MAX_BURST_SIZE]; // array of packets
> int num_mbufs; // num of mbufs
> int queue; // outgoing tx_queue
> int port; // outgoing port
> }
>
> struct batch * batches[MAX_BATCHES];
>
> /* dequeue a number of batches */
> int batch_count = rte_ring_sc_dequeue_bulk(some_rte_ring, (void **)
> &(batches), MAX_BATCHES, NULL);
>
> /* transmit out all pkts from every batch */
> if (likely(batch_count > 0)) {
> for (i = 0; i < batch_count; i++) {
> ret = rte_eth_tx_burst(batches[i]->port, batches[i]->queue, (struct
> rte_mbuf **) batches[i]->mbufs,
> batches[i]->num_mbufs);
> }
> }
>
> ==================
>
> At rte_eth_tx_burst(), I keep getting an error saying:
> myapp: /home/arvind/dpdk/drivers/net/mlx5/mlx5_rxtx.c:1652: uint16_t
> txq_burst_empw(struct mlx5_txq_data *, struct rte_mbuf **, uint16_t):
> Assertion `length == DATA_LEN(buf)' failed.
> OR
> myapp: /home/arvind/dpdk/drivers/net/mlx5/mlx5_rxtx.c:1609: uint16_t
> txq_burst_empw(struct mlx5_txq_data *, struct rte_mbuf **, uint16_t):
> Assertion `length == DATA_LEN(buf)' failed.
>
> I have debugged and ensured all the mbuf counts (at least in my code) are
> good. All the memory references to the mbufs also look good. However, I am
> not sure why Mellanox driver would complain.
>
> I have also tried to play with mlx5_rxtx.c by changing above lines to
> something like
> assert(length == pkts_n); // pkts_n is an argument passed to the func.
> Didn't help.
>
> Any thoughts?
Hi,
Does your mbuf pass rte_mbuf_check()?
That complaint is regarding mismatch between m->pkt_len and m->data_len.
If the mbuf is single segment packet (m->nb_segs == 1, m->next == NULL),
m->pkt_len should be same as m->data_len.
That assert() ins't strictly needed in the txq_burst_empw() though.
Thanks,
Yongseok
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