[dpdk-dev] [PATCH v1 1/7] net/mlx5: cleanup memory barriers

[Yongseok Koh <yskoh@mellanox.com>]

Updating a consumer index to HW doesn't require a memory barrier in case
that there's no updated data to be posted to HW, but a compiler barrier is
sufficient. rte_wmb() is replaced with rte_io_wmb() when it makes changes
visible to HW, not other core.

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
---
 drivers/net/mlx5/mlx5_rxtx.c         | 4 ++--
 drivers/net/mlx5/mlx5_rxtx.h         | 2 +-
 drivers/net/mlx5/mlx5_rxtx_vec_sse.c | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 9389383f6..275cd6a4b 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -1928,9 +1928,9 @@ mlx5_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		return 0;
 	/* Update the consumer index. */
 	rxq->rq_ci = rq_ci >> sges_n;
-	rte_wmb();
+	rte_io_wmb();
 	*rxq->cq_db = rte_cpu_to_be_32(rxq->cq_ci);
-	rte_wmb();
+	rte_io_wmb();
 	*rxq->rq_db = rte_cpu_to_be_32(rxq->rq_ci);
 #ifdef MLX5_PMD_SOFT_COUNTERS
 	/* Increment packets counter. */
diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
index 0bb71aeb0..8470a55ba 100644
--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -504,7 +504,7 @@ mlx5_tx_complete(struct mlx5_txq_data *txq)
 	txq->cq_ci = cq_ci;
 	txq->elts_tail = elts_tail;
 	/* Update the consumer index. */
-	rte_wmb();
+	rte_compiler_barrier();
 	*txq->cq_db = rte_cpu_to_be_32(cq_ci);
 }
 
diff --git a/drivers/net/mlx5/mlx5_rxtx_vec_sse.c b/drivers/net/mlx5/mlx5_rxtx_vec_sse.c
index 6d337ecd3..e8f0626a6 100644
--- a/drivers/net/mlx5/mlx5_rxtx_vec_sse.c
+++ b/drivers/net/mlx5/mlx5_rxtx_vec_sse.c
@@ -567,7 +567,7 @@ rxq_replenish_bulk_mbuf(struct mlx5_rxq_data *rxq, uint16_t n)
 		wq[i].addr = rte_cpu_to_be_64((uintptr_t)elts[i]->buf_addr +
 					      RTE_PKTMBUF_HEADROOM);
 	rxq->rq_ci += n;
-	rte_wmb();
+	rte_io_wmb();
 	*rxq->rq_db = rte_cpu_to_be_32(rxq->rq_ci);
 }
 
@@ -1259,7 +1259,7 @@ rxq_burst_v(struct mlx5_rxq_data *rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
 			rcvd_pkt += n;
 		}
 	}
-	rte_wmb();
+	rte_compiler_barrier();
 	*rxq->cq_db = rte_cpu_to_be_32(rxq->cq_ci);
 	return rcvd_pkt;
 }
-- 
2.11.0