[PATCH] event/eth_tx: prefetch mbuf headers

[Mattias Rönnblom]

On 2025-03-28 06:43, Mattias Rönnblom wrote:
> 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.ronnblom at ericsson.com>
> Tested-by: Peter Nilsson <peter.j.nilsson at ericsson.com>

What should be added is that what's been tested is the 
non-RTE_EVENT_TYPE_VECTOR case.

> ---
>   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)) {
> +			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;