[dpdk-dev] [PATCH] net/i40e: add additional prefetch instructions for bulk rx

[Vladyslav Buslov]

Added prefetch of first packet payload cacheline in i40e_rx_scan_hw_ring
Added prefetch of second mbuf cacheline in i40e_rx_alloc_bufs

Signed-off-by: Vladyslav Buslov <vladyslav.buslov at harmonicinc.com>
---
 drivers/net/i40e/i40e_rxtx.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
index d3cfb98..e493fb4 100644
--- a/drivers/net/i40e/i40e_rxtx.c
+++ b/drivers/net/i40e/i40e_rxtx.c
@@ -1003,6 +1003,7 @@ i40e_rx_scan_hw_ring(struct i40e_rx_queue *rxq)
 		/* Translate descriptor info to mbuf parameters */
 		for (j = 0; j < nb_dd; j++) {
 			mb = rxep[j].mbuf;
+			rte_prefetch0(RTE_PTR_ADD(mb->buf_addr, RTE_PKTMBUF_HEADROOM));
 			qword1 = rte_le_to_cpu_64(\
 				rxdp[j].wb.qword1.status_error_len);
 			pkt_len = ((qword1 & I40E_RXD_QW1_LENGTH_PBUF_MASK) >>
@@ -1086,9 +1087,11 @@ i40e_rx_alloc_bufs(struct i40e_rx_queue *rxq)
 
 	rxdp = &rxq->rx_ring[alloc_idx];
 	for (i = 0; i < rxq->rx_free_thresh; i++) {
-		if (likely(i < (rxq->rx_free_thresh - 1)))
+		if (likely(i < (rxq->rx_free_thresh - 1))) {
 			/* Prefetch next mbuf */
-			rte_prefetch0(rxep[i + 1].mbuf);
+			rte_prefetch0(&rxep[i + 1].mbuf->cacheline0);
+			rte_prefetch0(&rxep[i + 1].mbuf->cacheline1);
+		}
 
 		mb = rxep[i].mbuf;
 		rte_mbuf_refcnt_set(mb, 1);
-- 
2.8.3