[dpdk-dev] [PATCH v1 1/2] net/i40e: improve performance for scalar Tx

[Feifei Wang]

For i40e scalar Tx path, if implement FAST_FREE_MBUF mode, it means
per-queue all mbufs come from the same mempool and have refcnt = 1.

Thus we can use bulk free of the buffers when mbuf fast free mode is
enabled.

For scalar path in arm platform:
In n1sdp, performance is improved by 7.8%;
In thunderx2, performance is improved by 6.7%.

For scalar path in x86 platform,
performance is improved by 6%.

Suggested-by: Ruifeng Wang <ruifeng.wang at arm.com>
Signed-off-by: Feifei Wang <feifei.wang2 at arm.com>
---
 drivers/net/i40e/i40e_rxtx.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
index 6c58decece..fe7b20f750 100644
--- a/drivers/net/i40e/i40e_rxtx.c
+++ b/drivers/net/i40e/i40e_rxtx.c
@@ -1295,6 +1295,7 @@ i40e_tx_free_bufs(struct i40e_tx_queue *txq)
 {
 	struct i40e_tx_entry *txep;
 	uint16_t i;
+	struct rte_mbuf *free[RTE_I40E_TX_MAX_FREE_BUF_SZ];
 
 	if ((txq->tx_ring[txq->tx_next_dd].cmd_type_offset_bsz &
 			rte_cpu_to_le_64(I40E_TXD_QW1_DTYPE_MASK)) !=
@@ -1308,9 +1309,11 @@ i40e_tx_free_bufs(struct i40e_tx_queue *txq)
 
 	if (txq->offloads & DEV_TX_OFFLOAD_MBUF_FAST_FREE) {
 		for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
-			rte_mempool_put(txep->mbuf->pool, txep->mbuf);
+			free[i] = txep->mbuf;
 			txep->mbuf = NULL;
 		}
+		rte_mempool_put_bulk(free[0]->pool, (void **)free,
+					txq->tx_rs_thresh);
 	} else {
 		for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
 			rte_pktmbuf_free_seg(txep->mbuf);
-- 
2.25.1