> -----Original Message-----
> From: Mattias Rönnblom <hof...@lysator.liu.se>
> Sent: Thursday, July 3, 2025 1:50 AM
> To: Naga Harish K, S V <s.v.naga.haris...@intel.com>; Mattias Rönnblom
> <mattias.ronnb...@ericsson.com>; dev@dpdk.org
> Cc: Jerin Jacob <jer...@marvell.com>; Peter Nilsson
> <peter.j.nils...@ericsson.com>
> Subject: Re: [PATCH] event/eth_tx: prefetch mbuf headers
>
> On 2025-05-27 12:55, Naga Harish K, S V wrote:
> >
> >
> >> -----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?
> >
>
> Yes.
I think all event-types need to be equally weighted. My ask was to remove the
"unlikely" for vector events.
>
> >> {
> >> + 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
> >
