net/mlx5e: Support enhanced CQE compression

CQE compression feature improves performance by reducing PCI bandwidth
bottleneck on CQEs write.
Enhanced CQE compression introduced in ConnectX-6 and it aims to reduce
CPU utilization of SW side packets decompression by eliminating the
need to rewrite ownership bit, which is likely to cost a cache-miss, is
replaced by validity byte handled solely by HW.
Another advantage of the enhanced feature is that session packets are
available to SW as soon as a single CQE slot is filled, instead of
waiting for session to close, this improves packet latency from NIC to
host.

Performance:
Following are tested scenarios and reults comparing basic and enahnced
CQE compression.

setup: IXIA 100GbE connected directly to port 0 and port 1 of
ConnectX-6 Dx 100GbE dual port.

Case #1 RX only, single flow goes to single queue:
IRQ rate reduced by ~ 30%, CPU utilization improved by 2%.

Case #2 IP forwarding from port 1 to port 0 single flow goes to
single queue:
Avg latency improved from 60us to 21us, frame loss improved from 0.5% to 0.0%.

Case #3 IP forwarding from port 1 to port 0 Max Throughput IXIA sends
100%, 8192 UDP flows, goes to 24 queues:
Enhanced is equal or slightly better than basic.

Testing the basic compression feature with this patch shows there is
no perfrormance degradation of the basic compression feature.

Signed-off-by: Ofer Levi <oferle@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/wq.h b/drivers/net/ethernet/mellanox/mlx5/core/wq.h
index 4d629e5ddbc7..e4ef1d24a3ad 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/wq.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/wq.h
@@ -243,6 +243,23 @@ static inline struct mlx5_cqe64 *mlx5_cqwq_get_cqe(struct mlx5_cqwq *wq)
 	return cqe;
 }
 
+static inline
+struct mlx5_cqe64 *mlx5_cqwq_get_cqe_enahnced_comp(struct mlx5_cqwq *wq)
+{
+	u8 sw_validity_iteration_count = mlx5_cqwq_get_wrap_cnt(wq) & 0xff;
+	u32 ci = mlx5_cqwq_get_ci(wq);
+	struct mlx5_cqe64 *cqe;
+
+	cqe = mlx5_cqwq_get_wqe(wq, ci);
+	if (cqe->validity_iteration_count != sw_validity_iteration_count)
+		return NULL;
+
+	/* ensure cqe content is read after cqe ownership bit/validity byte */
+	dma_rmb();
+
+	return cqe;
+}
+
 static inline u32 mlx5_wq_ll_get_size(struct mlx5_wq_ll *wq)
 {
 	return (u32)wq->fbc.sz_m1 + 1;