[PATCH] net/null: Add fast mbuf release TX offload

[Morten Brørup]

Added fast mbuf release, re-using the existing mbuf pool pointer
in the queue structure.

Signed-off-by: Morten Brørup <m...@smartsharesystems.com>
---
 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;
        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;
-- 
2.43.0