> Previously, the TX burst size was fixed at 256, leading to performance
> degradation in certain scenarios.
>
> This patch introduces logic to set the TX burst size to match the
> configured RX burst size (--burst option, default 32, max 512)
> for better efficiency.
>
> Fixes: d5c4897ecfb2 ("examples/l3fwd: add option to set Rx burst size")
> Cc: haij...@huawei.com
> Cc: sta...@dpdk.org
>
> Signed-off-by: Sivaprasad Tummala <sivaprasad.tumm...@amd.com>
> ---
> examples/l3fwd/l3fwd.h | 6 +++---
> examples/l3fwd/l3fwd_common.h | 11 +++++++----
> examples/l3fwd/main.c | 2 ++
> 3 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/examples/l3fwd/l3fwd.h b/examples/l3fwd/l3fwd.h
> index 0cce3406ee..9d7c73504b 100644
> --- a/examples/l3fwd/l3fwd.h
> +++ b/examples/l3fwd/l3fwd.h
> @@ -35,7 +35,7 @@
> /*
> * Try to avoid TX buffering if we have at least MAX_TX_BURST packets to
> send.
> */
> -#define MAX_TX_BURST (MAX_PKT_BURST / 2)
> +#define MAX_TX_BURST (DEFAULT_PKT_BURST / 2)
>
> #define NB_SOCKETS 8
>
> @@ -152,8 +152,8 @@ send_single_packet(struct lcore_conf *qconf,
> len++;
>
> /* enough pkts to be sent */
> - if (unlikely(len == MAX_PKT_BURST)) {
> - send_burst(qconf, MAX_PKT_BURST, port);
> + if (unlikely(len == nb_pkt_per_burst)) {
> + send_burst(qconf, nb_pkt_per_burst, port);
> len = 0;
> }
>
> diff --git a/examples/l3fwd/l3fwd_common.h b/examples/l3fwd/l3fwd_common.h
> index d94e5f1357..6cb7de5144 100644
> --- a/examples/l3fwd/l3fwd_common.h
> +++ b/examples/l3fwd/l3fwd_common.h
> @@ -25,6 +25,9 @@
> */
> #define SENDM_PORT_OVERHEAD(x) (x)
>
> +extern uint32_t nb_pkt_per_burst;
> +extern uint32_t max_tx_burst;
> +
> /*
> * From http://www.rfc-editor.org/rfc/rfc1812.txt section 5.2.2:
> * - The IP version number must be 4.
> @@ -71,7 +74,7 @@ send_packetsx4(struct lcore_conf *qconf, uint16_t port,
> struct rte_mbuf *m[],
> * If TX buffer for that queue is empty, and we have enough packets,
> * then send them straightway.
> */
> - if (num >= MAX_TX_BURST && len == 0) {
> + if (num >= max_tx_burst && len == 0) {
> n = rte_eth_tx_burst(port, qconf->tx_queue_id[port], m, num);
> if (unlikely(n < num)) {
> do {
> @@ -86,7 +89,7 @@ send_packetsx4(struct lcore_conf *qconf, uint16_t port,
> struct rte_mbuf *m[],
> */
>
> n = len + num;
> - n = (n > MAX_PKT_BURST) ? MAX_PKT_BURST - len : num;
> + n = (n > nb_pkt_per_burst) ? nb_pkt_per_burst - len : num;
>
> j = 0;
> switch (n % FWDSTEP) {
> @@ -112,9 +115,9 @@ send_packetsx4(struct lcore_conf *qconf, uint16_t port,
> struct rte_mbuf *m[],
> len += n;
>
> /* enough pkts to be sent */
> - if (unlikely(len == MAX_PKT_BURST)) {
> + if (unlikely(len == nb_pkt_per_burst)) {
>
> - send_burst(qconf, MAX_PKT_BURST, port);
> + send_burst(qconf, nb_pkt_per_burst, port);
>
> /* copy rest of the packets into the TX buffer. */
> len = num - n;
> diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
> index 994b7dd8e5..4cabd05be2 100644
> --- a/examples/l3fwd/main.c
> +++ b/examples/l3fwd/main.c
> @@ -59,6 +59,7 @@ uint16_t nb_rxd = RX_DESC_DEFAULT;
> uint16_t nb_txd = TX_DESC_DEFAULT;
> uint32_t nb_pkt_per_burst = DEFAULT_PKT_BURST;
> uint32_t mb_mempool_cache_size = MEMPOOL_CACHE_SIZE;
> +uint32_t max_tx_burst = MAX_TX_BURST;
>
> /**< Ports set in promiscuous mode off by default. */
> static int promiscuous_on;
> @@ -733,6 +734,7 @@ parse_pkt_burst(const char *optarg)
> return;
> }
> nb_pkt_per_burst = burst_size;
> + max_tx_burst = burst_size / 2;
Might be a bit better then to completely remove MAX_TX_BURST,
and just always set:
max_tx_burst = nb_pkt_per_burst / 2;
> RTE_LOG(INFO, L3FWD, "Using PMD-provided burst value %d\n", burst_size);
> }
>
> --
> 2.34.1
