From: Sagi Grimberg <sagi@grimberg.me>
To: dev@dpdk.org
Cc: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>,
Adrien Mazarguil <adrien.mazarguil@6wind.com>,
Shahaf Shuler <shahafs@mellanox.com>
Subject: [dpdk-dev] [PATCH 1/2] net/mlx5: replace memory barrier type
Date: Mon, 21 Aug 2017 10:47:01 +0300 [thread overview]
Message-ID: <1503301622-14220-2-git-send-email-sagi@grimberg.me> (raw)
In-Reply-To: <1503301622-14220-1-git-send-email-sagi@grimberg.me>
From: 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_compiler_barrier as it acts as a write memory barrier.
More details on this type of barrier can be found on [1]
Replacing the rte_wmb is also expected to improve the throughput.
[1] https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html
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>
---
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 7de1d10863e5..59b9ff24fb82 100644
--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -602,7 +602,7 @@ 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_compiler_barrier();
*txq->qp_db = htonl(txq->wqe_ci);
/* Ensure ordering between DB record and BF copy. */
rte_wmb();
--
2.7.4
next prev parent reply other threads:[~2017-08-21 7:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-21 7:47 [dpdk-dev] [PATCH 0/2] mlx5 high latency observed on send operations Sagi Grimberg
2017-08-21 7:47 ` Sagi Grimberg [this message]
2017-08-23 11:39 ` [dpdk-dev] [PATCH 1/2] net/mlx5: replace memory barrier type Nélio Laranjeiro
2017-08-23 13:11 ` Bruce Richardson
2017-08-24 6:56 ` Shahaf Shuler
2017-08-24 9:27 ` Bruce Richardson
2017-08-21 7:47 ` [dpdk-dev] [PATCH 2/2] net/mlx5: don't map doorbell register to write combining Sagi Grimberg
2017-08-23 11:03 ` Ferruh Yigit
2017-08-23 12:06 ` Nélio Laranjeiro
2017-08-27 6:47 ` [dpdk-dev] [PATCH v2 0/2] mlx5 high latency observed on send operations Shahaf Shuler
2017-08-27 6:47 ` [dpdk-dev] [PATCH v2 1/2] net/mlx5: replace memory barrier type Shahaf Shuler
2017-08-27 6:47 ` [dpdk-dev] [PATCH v2 2/2] net/mlx5: don't map doorbell register to write combining Shahaf Shuler
2017-08-29 16:53 ` [dpdk-dev] [PATCH v2 0/2] mlx5 high latency observed on send operations Ferruh Yigit
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