> -----Original Message-----
> From: Mattias Rönnblom <mattias.ronnb...@ericsson.com>
> Sent: Friday, March 28, 2025 11:14 AM
> To: dev@dpdk.org
> Cc: Mattias Rönnblom <hof...@lysator.liu.se>; Naga Harish K, S V
> <s.v.naga.haris...@intel.com>; Jerin Jacob <jer...@marvell.com>; Mattias
> Rönnblom <mattias.ronnb...@ericsson.com>; Peter Nilsson
> <peter.j.nils...@ericsson.com>
> Subject: [PATCH] event/eth_tx: prefetch mbuf headers
>
> Prefetch mbuf headers, resulting in ~10% throughput improvement when the
> Ethernet RX and TX Adapters are hosted on the same core (likely ~2x in case a
> dedicated TX core is used).
>
> Signed-off-by: Mattias Rönnblom <mattias.ronnb...@ericsson.com>
> Tested-by: Peter Nilsson <peter.j.nils...@ericsson.com>
> ---
> lib/eventdev/rte_event_eth_tx_adapter.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/lib/eventdev/rte_event_eth_tx_adapter.c
> b/lib/eventdev/rte_event_eth_tx_adapter.c
> index 67fff8b7d6..d740ae00f9 100644
> --- a/lib/eventdev/rte_event_eth_tx_adapter.c
> +++ b/lib/eventdev/rte_event_eth_tx_adapter.c
> @@ -598,6 +598,12 @@ txa_process_event_vector(struct txa_service_data
> *txa,
> return nb_tx;
> }
>
> +static inline void
> +txa_prefetch_mbuf(struct rte_mbuf *mbuf) {
> + rte_mbuf_prefetch_part1(mbuf);
> +}
> +
> static void
> txa_service_tx(struct txa_service_data *txa, struct rte_event *ev,
> uint32_t n)
> @@ -608,6 +614,20 @@ txa_service_tx(struct txa_service_data *txa, struct
> rte_event *ev,
>
> stats = &txa->stats;
>
> + for (i = 0; i < n; i++) {
> + struct rte_event *event = &ev[i];
> +
> + if (unlikely(event->event_type & RTE_EVENT_TYPE_VECTOR))
This gives a branch prediction advantage to non-vector events. Is that the
intention?
> {
> + struct rte_event_vector *vec = event->vec;
> + struct rte_mbuf **mbufs = vec->mbufs;
> + uint32_t k;
> +
> + for (k = 0; k < vec->nb_elem; k++)
> + txa_prefetch_mbuf(mbufs[k]);
> + } else
> + txa_prefetch_mbuf(event->mbuf);
> + }
> +
> nb_tx = 0;
> for (i = 0; i < n; i++) {
> uint16_t port;
> --
> 2.43.0
