[dpdk-dev] [PATCH v2 ] ixgbe: speed up transmit

[Stephen Hemminger <stephen@networkplumber.org>]

From: Stephen Hemminger <shemming@brocade.com>

The freeing of mbuf's in ixgbe is one of the observable hot spots
under load. Optimize it by doing bulk free of mbufs using code similar
to i40e and fm10k.

Drop the no longer needed micro-optimization for the no refcount flag.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
v2 - rebase and use variable names consistent with i40e

 drivers/net/ixgbe/ixgbe_rxtx.c | 32 ++++++++++++++++++++------------
 drivers/net/ixgbe/ixgbe_rxtx.h |  2 +-
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
index 52a263c..0b087c3 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx.c
@@ -126,7 +126,8 @@ ixgbe_tx_free_bufs(struct ixgbe_tx_queue *txq)
 {
 	struct ixgbe_tx_entry *txep;
 	uint32_t status;
-	int i;
+	int i, nb_free = 0;
+	struct rte_mbuf *m, *free[RTE_IXGBE_TX_MAX_FREE_BUF_SZ];
 
 	/* check DD bit on threshold descriptor */
 	status = txq->tx_ring[txq->tx_next_dd].wb.status;
@@ -139,20 +140,27 @@ ixgbe_tx_free_bufs(struct ixgbe_tx_queue *txq)
 	 */
 	txep = &(txq->sw_ring[txq->tx_next_dd - (txq->tx_rs_thresh - 1)]);
 
-	/* free buffers one at a time */
-	if ((txq->txq_flags & (uint32_t)ETH_TXQ_FLAGS_NOREFCOUNT) != 0) {
-		for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
-			txep->mbuf->next = NULL;
-			rte_mempool_put(txep->mbuf->pool, txep->mbuf);
-			txep->mbuf = NULL;
-		}
-	} else {
-		for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
-			rte_pktmbuf_free_seg(txep->mbuf);
-			txep->mbuf = NULL;
+	for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
+		/* free buffers one at a time */
+		m = __rte_pktmbuf_prefree_seg(txep->mbuf);
+		txep->mbuf = NULL;
+
+		if (unlikely(m == NULL))
+			continue;
+
+		if (nb_free >= RTE_IXGBE_TX_MAX_FREE_BUF_SZ ||
+		    (nb_free > 0 && m->pool != free[0]->pool)) {
+			rte_mempool_put_bulk(free[0]->pool,
+					     (void **)free, nb_free);
+			nb_free = 0;
 		}
+
+		free[nb_free++] = m;
 	}
 
+	if (nb_free > 0)
+		rte_mempool_put_bulk(free[0]->pool, (void **)free, nb_free);
+
 	/* buffers were freed, update counters */
 	txq->nb_tx_free = (uint16_t)(txq->nb_tx_free + txq->tx_rs_thresh);
 	txq->tx_next_dd = (uint16_t)(txq->tx_next_dd + txq->tx_rs_thresh);
diff --git a/drivers/net/ixgbe/ixgbe_rxtx.h b/drivers/net/ixgbe/ixgbe_rxtx.h
index 475a800..064cbda 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.h
+++ b/drivers/net/ixgbe/ixgbe_rxtx.h
@@ -58,6 +58,7 @@
 
 #define RTE_PMD_IXGBE_TX_MAX_BURST 32
 #define RTE_PMD_IXGBE_RX_MAX_BURST 32
+#define RTE_IXGBE_TX_MAX_FREE_BUF_SZ 64
 
 #define RTE_IXGBE_DESCS_PER_LOOP    4
 
@@ -70,7 +71,6 @@
 #ifdef RTE_IXGBE_INC_VECTOR
 #define RTE_IXGBE_RXQ_REARM_THRESH      32
 #define RTE_IXGBE_MAX_RX_BURST          RTE_IXGBE_RXQ_REARM_THRESH
-#define RTE_IXGBE_TX_MAX_FREE_BUF_SZ    64
 #endif
 
 #define RX_RING_SZ ((IXGBE_MAX_RING_DESC + RTE_IXGBE_DESCS_PER_LOOP - 1) * \
-- 
2.1.4