[dpdk-dev] [PATCH v2 1/7] net/qede: remove flags from Tx entry

[Balazs Nemeth]

Each sw_tx_ring entry was of type struct qede_tx_entry:

struct qede_tx_entry {
       struct rte_mbuf *mbuf;
       uint8_t flags;
};

Leaving the unused flags member here has a few performance implications.
First, each qede_tx_entry takes up more memory which has caching
implications as less entries fit in a cache line while multiple entries
are frequently handled in batches. Second, an array of qede_tx_entry
entries is incompatible with existing APIs that expect an array of
rte_mbuf pointers. Consequently, an extra array need to be allocated
before calling such APIs and each entry needs to be copied over.

This patch omits the flags field and replaces the qede_tx_entry entry
by a simple rte_mbuf pointer.

Signed-off-by: Balazs Nemeth <bnemeth at redhat.com>
Reviewed-by: Igor Russkikh <irusskikh at marvell.com>
---
 drivers/net/qede/qede_rxtx.c | 22 ++++++++++++----------
 drivers/net/qede/qede_rxtx.h | 10 +---------
 2 files changed, 13 insertions(+), 19 deletions(-)

diff --git a/drivers/net/qede/qede_rxtx.c b/drivers/net/qede/qede_rxtx.c
index 87f52d725..d2f77ed2e 100644
--- a/drivers/net/qede/qede_rxtx.c
+++ b/drivers/net/qede/qede_rxtx.c
@@ -393,6 +393,7 @@ qede_alloc_tx_queue_mem(struct rte_eth_dev *dev,
 	struct ecore_dev *edev = &qdev->edev;
 	struct qede_tx_queue *txq;
 	int rc;
+	size_t sw_tx_ring_size;
 
 	txq = rte_zmalloc_socket("qede_tx_queue", sizeof(struct qede_tx_queue),
 				 RTE_CACHE_LINE_SIZE, socket_id);
@@ -425,9 +426,9 @@ qede_alloc_tx_queue_mem(struct rte_eth_dev *dev,
 	}
 
 	/* Allocate software ring */
+	sw_tx_ring_size = sizeof(txq->sw_tx_ring) * txq->nb_tx_desc;
 	txq->sw_tx_ring = rte_zmalloc_socket("txq->sw_tx_ring",
-					     (sizeof(struct qede_tx_entry) *
-					      txq->nb_tx_desc),
+					     sw_tx_ring_size,
 					     RTE_CACHE_LINE_SIZE, socket_id);
 
 	if (!txq->sw_tx_ring) {
@@ -523,9 +524,9 @@ static void qede_tx_queue_release_mbufs(struct qede_tx_queue *txq)
 
 	if (txq->sw_tx_ring) {
 		for (i = 0; i < txq->nb_tx_desc; i++) {
-			if (txq->sw_tx_ring[i].mbuf) {
-				rte_pktmbuf_free(txq->sw_tx_ring[i].mbuf);
-				txq->sw_tx_ring[i].mbuf = NULL;
+			if (txq->sw_tx_ring[i]) {
+				rte_pktmbuf_free(txq->sw_tx_ring[i]);
+				txq->sw_tx_ring[i] = NULL;
 			}
 		}
 	}
@@ -889,10 +890,11 @@ qede_free_tx_pkt(struct qede_tx_queue *txq)
 	uint16_t idx;
 
 	idx = TX_CONS(txq);
-	mbuf = txq->sw_tx_ring[idx].mbuf;
+	mbuf = txq->sw_tx_ring[idx];
 	if (mbuf) {
 		nb_segs = mbuf->nb_segs;
 		PMD_TX_LOG(DEBUG, txq, "nb_segs to free %u\n", nb_segs);
+
 		while (nb_segs) {
 			/* It's like consuming rxbuf in recv() */
 			ecore_chain_consume(&txq->tx_pbl);
@@ -900,7 +902,7 @@ qede_free_tx_pkt(struct qede_tx_queue *txq)
 			nb_segs--;
 		}
 		rte_pktmbuf_free(mbuf);
-		txq->sw_tx_ring[idx].mbuf = NULL;
+		txq->sw_tx_ring[idx] = NULL;
 		txq->sw_tx_cons++;
 		PMD_TX_LOG(DEBUG, txq, "Freed tx packet\n");
 	} else {
@@ -2243,7 +2245,7 @@ qede_xmit_pkts_regular(void *p_txq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	struct eth_tx_3rd_bd *bd3;
 	struct rte_mbuf *m_seg = NULL;
 	struct rte_mbuf *mbuf;
-	struct qede_tx_entry *sw_tx_ring;
+	struct rte_mbuf **sw_tx_ring;
 	uint16_t nb_tx_pkts;
 	uint16_t bd_prod;
 	uint16_t idx;
@@ -2306,7 +2308,7 @@ qede_xmit_pkts_regular(void *p_txq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 
 		/* Fill the entry in the SW ring and the BDs in the FW ring */
 		idx = TX_PROD(txq);
-		sw_tx_ring[idx].mbuf = mbuf;
+		sw_tx_ring[idx] = mbuf;
 
 		/* BD1 */
 		bd1 = (struct eth_tx_1st_bd *)ecore_chain_produce(&txq->tx_pbl);
@@ -2612,7 +2614,7 @@ qede_xmit_pkts(void *p_txq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 
 		/* Fill the entry in the SW ring and the BDs in the FW ring */
 		idx = TX_PROD(txq);
-		txq->sw_tx_ring[idx].mbuf = mbuf;
+		txq->sw_tx_ring[idx] = mbuf;
 
 		/* BD1 */
 		bd1 = (struct eth_tx_1st_bd *)ecore_chain_produce(&txq->tx_pbl);
diff --git a/drivers/net/qede/qede_rxtx.h b/drivers/net/qede/qede_rxtx.h
index fcb564a1b..335016847 100644
--- a/drivers/net/qede/qede_rxtx.h
+++ b/drivers/net/qede/qede_rxtx.h
@@ -203,14 +203,6 @@ struct qede_rx_queue {
 	void *handle;
 };
 
-/*
- * TX BD descriptor ring
- */
-struct qede_tx_entry {
-	struct rte_mbuf *mbuf;
-	uint8_t flags;
-};
-
 union db_prod {
 	struct eth_db_data data;
 	uint32_t raw;
@@ -220,7 +212,7 @@ struct qede_tx_queue {
 	/* Always keep qdev as first member */
 	struct qede_dev *qdev;
 	struct ecore_chain tx_pbl;
-	struct qede_tx_entry *sw_tx_ring;
+	struct rte_mbuf **sw_tx_ring;
 	uint16_t nb_tx_desc;
 	uint16_t nb_tx_avail;
 	uint16_t tx_free_thresh;
-- 
2.30.2