netdev - [net-next 11/14] net/mlx5e: Use CQE padding for Ethernet CQs

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Date:   Tue, 11 Dec 2018 15:24:06 -0800
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Daniel Jurgens <danielj@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net-next 11/14] net/mlx5e: Use CQE padding for Ethernet CQs

From: Daniel Jurgens <danielj@...lanox.com>

Writing 64B CQEs to 128B cache lines results in a RMW operation. Padding
the CQEs to 128B if possible improves performance on 128B cache line
systems like PPC.

Testing on PPC showed up to a 24% improvement in small packet throughput
vs the default behavior, depending on the workload and system topology.

Signed-off-by: Daniel Jurgens <danielj@...lanox.com>
Reviewed-by: Tariq Toukan <tariqt@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c |  2 ++
 drivers/net/ethernet/mellanox/mlx5/core/wq.c      |  3 ++-
 drivers/net/ethernet/mellanox/mlx5/core/wq.h      |  7 ++++++-
 include/linux/mlx5/cq.h                           | 10 +++++-----
 4 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 88116a4750b0..2188e5ba908f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -2224,6 +2224,8 @@ static void mlx5e_build_common_cq_param(struct mlx5e_priv *priv,
 	void *cqc = param->cqc;
 
 	MLX5_SET(cqc, cqc, uar_page, priv->mdev->priv.uar->index);
+	if (MLX5_CAP_GEN(priv->mdev, cqe_128_always) && cache_line_size() >= 128)
+		MLX5_SET(cqc, cqc, cqe_sz, CQE_STRIDE_128_PAD);
 }
 
 static void mlx5e_build_rx_cq_param(struct mlx5e_priv *priv,
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/wq.c b/drivers/net/ethernet/mellanox/mlx5/core/wq.c
index 2dcbf1ebfd6a..953cc8efba69 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/wq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/wq.c
@@ -155,7 +155,8 @@ int mlx5_cqwq_create(struct mlx5_core_dev *mdev, struct mlx5_wq_param *param,
 		     void *cqc, struct mlx5_cqwq *wq,
 		     struct mlx5_wq_ctrl *wq_ctrl)
 {
-	u8 log_wq_stride = MLX5_GET(cqc, cqc, cqe_sz) + 6;
+	/* CQE_STRIDE_128 and CQE_STRIDE_128_PAD both mean 128B stride */
+	u8 log_wq_stride = MLX5_GET(cqc, cqc, cqe_sz) == CQE_STRIDE_64 ? 6 : 7;
 	u8 log_wq_sz     = MLX5_GET(cqc, cqc, log_cq_size);
 	int err;
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/wq.h b/drivers/net/ethernet/mellanox/mlx5/core/wq.h
index 9bc2184a46bc..ea934a48c90a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/wq.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/wq.h
@@ -179,7 +179,12 @@ static inline u32 mlx5_cqwq_get_ci(struct mlx5_cqwq *wq)
 
 static inline struct mlx5_cqe64 *mlx5_cqwq_get_wqe(struct mlx5_cqwq *wq, u32 ix)
 {
-	return mlx5_frag_buf_get_wqe(&wq->fbc, ix);
+	struct mlx5_cqe64 *cqe = mlx5_frag_buf_get_wqe(&wq->fbc, ix);
+
+	/* For 128B CQEs the data is in the last 64B */
+	cqe += wq->fbc.log_stride == 7;
+
+	return cqe;
 }
 
 static inline u32 mlx5_cqwq_get_ctr_wrap_cnt(struct mlx5_cqwq *wq, u32 ctr)
diff --git a/include/linux/mlx5/cq.h b/include/linux/mlx5/cq.h
index 28b757a64029..612c8c2f2466 100644
--- a/include/linux/mlx5/cq.h
+++ b/include/linux/mlx5/cq.h
@@ -125,9 +125,9 @@ struct mlx5_cq_modify_params {
 };
 
 enum {
-	CQE_SIZE_64 = 0,
-	CQE_SIZE_128 = 1,
-	CQE_SIZE_128_PAD = 2,
+	CQE_STRIDE_64 = 0,
+	CQE_STRIDE_128 = 1,
+	CQE_STRIDE_128_PAD = 2,
 };
 
 #define MLX5_MAX_CQ_PERIOD (BIT(__mlx5_bit_sz(cqc, cq_period)) - 1)
@@ -135,8 +135,8 @@ enum {
 
 static inline int cqe_sz_to_mlx_sz(u8 size, int padding_128_en)
 {
-	return padding_128_en ? CQE_SIZE_128_PAD :
-				size == 64 ? CQE_SIZE_64 : CQE_SIZE_128;
+	return padding_128_en ? CQE_STRIDE_128_PAD :
+				size == 64 ? CQE_STRIDE_64 : CQE_STRIDE_128;
 }
 
 static inline void mlx5_cq_set_ci(struct mlx5_core_cq *cq)
-- 
2.19.2