[dpdk-dev] [PATCH v2 1/2] net/mlx5: replace memory barrier type

[Shahaf Shuler <shahafs@mellanox.com>]

The reason for the requirement of a barrier between the txq writes
and the doorbell record writes is to avoid a case where the device
reads the doorbell record's new value before the txq writes are flushed
to memory.

The current use of rte_wmb is not necessary, and can be replaced by
rte_io_wmb which is more relaxed.

Replacing the rte_wmb is also expected to improve the throughput.

on v2:
 * replace compiler barrier with rte_io_wmb.

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Signed-off-by: Alexander Solganik <solganik@gmail.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
---
 drivers/net/mlx5/mlx5_rxtx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
index b3b161da5..e9895a9c0 100644
--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -591,7 +591,7 @@ mlx5_tx_dbrec(struct txq *txq, volatile struct mlx5_wqe *wqe)
 	uint64_t *dst = (uint64_t *)((uintptr_t)txq->bf_reg);
 	volatile uint64_t *src = ((volatile uint64_t *)wqe);
 
-	rte_wmb();
+	rte_io_wmb();
 	*txq->qp_db = htonl(txq->wqe_ci);
 	/* Ensure ordering between DB record and BF copy. */
 	rte_wmb();
-- 
2.12.0