On Tue, 24 Jun 2025 18:14:16 +0000
Morten Brørup <m...@smartsharesystems.com> wrote:
> Added fast mbuf release, re-using the existing mbuf pool pointer
> in the queue structure.
>
> Signed-off-by: Morten Brørup <m...@smartsharesystems.com>
Makes sense.
> ---
> drivers/net/null/rte_eth_null.c | 30 +++++++++++++++++++++++++++---
> 1 file changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/null/rte_eth_null.c b/drivers/net/null/rte_eth_null.c
> index 8a9b74a03b..12c0d8d1ff 100644
> --- a/drivers/net/null/rte_eth_null.c
> +++ b/drivers/net/null/rte_eth_null.c
> @@ -34,6 +34,17 @@ struct pmd_internals;
> struct null_queue {
> struct pmd_internals *internals;
>
> + /**
> + * For RX queue:
> + * Mempool to allocate mbufs from.
> + *
> + * For TX queue:
> + * Mempool to free mbufs to, if fast release of mbufs is enabled.
> + * UINTPTR_MAX if the mempool for fast release of mbufs has not yet
> been detected.
> + * NULL if fast release of mbufs is not enabled.
> + *
> + * @see RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE
> + */
> struct rte_mempool *mb_pool;
Do all drivers to it this way?
Is it documented in ethdev?
> void *dummy_packet;
>
> @@ -151,7 +162,16 @@ eth_null_tx(void *q, struct rte_mbuf **bufs, uint16_t
> nb_bufs)
> for (i = 0; i < nb_bufs; i++)
> bytes += rte_pktmbuf_pkt_len(bufs[i]);
>
> - rte_pktmbuf_free_bulk(bufs, nb_bufs);
> + if (h->mb_pool != NULL) { /* RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE */
> + if (unlikely(h->mb_pool == (void *)UINTPTR_MAX)) {
> + if (unlikely(nb_bufs == 0))
> + return 0; /* Do not dereference uninitialized
> bufs[0]. */
> + h->mb_pool = bufs[0]->pool;
> + }
> + rte_mbuf_raw_free_bulk(h->mb_pool, bufs, nb_bufs);
> + } else {
> + rte_pktmbuf_free_bulk(bufs, nb_bufs);
> + }
> rte_atomic_fetch_add_explicit(&h->tx_pkts, nb_bufs,
> rte_memory_order_relaxed);
> rte_atomic_fetch_add_explicit(&h->tx_bytes, bytes,
> rte_memory_order_relaxed);
>
> @@ -259,7 +279,7 @@ static int
> eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t tx_queue_id,
> uint16_t nb_tx_desc __rte_unused,
> unsigned int socket_id __rte_unused,
> - const struct rte_eth_txconf *tx_conf __rte_unused)
> + const struct rte_eth_txconf *tx_conf)
> {
> struct rte_mbuf *dummy_packet;
> struct pmd_internals *internals;
> @@ -284,6 +304,9 @@ eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t
> tx_queue_id,
>
> internals->tx_null_queues[tx_queue_id].internals = internals;
> internals->tx_null_queues[tx_queue_id].dummy_packet = dummy_packet;
> + internals->tx_null_queues[tx_queue_id].mb_pool =
> + tx_conf->offloads & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE ?
> + (void *)UINTPTR_MAX : NULL;
>
> return 0;
> }
> @@ -309,7 +332,8 @@ eth_dev_info(struct rte_eth_dev *dev,
> dev_info->max_rx_queues = RTE_DIM(internals->rx_null_queues);
> dev_info->max_tx_queues = RTE_DIM(internals->tx_null_queues);
> dev_info->min_rx_bufsize = 0;
> - dev_info->tx_offload_capa = RTE_ETH_TX_OFFLOAD_MULTI_SEGS |
> RTE_ETH_TX_OFFLOAD_MT_LOCKFREE;
> + dev_info->tx_offload_capa = RTE_ETH_TX_OFFLOAD_MULTI_SEGS |
> + RTE_ETH_TX_OFFLOAD_MT_LOCKFREE |
> RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE;
>
> dev_info->reta_size = internals->reta_size;
> dev_info->flow_type_rss_offloads = internals->flow_type_rss_offloads;
