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Commit 4c07c132 authored by Tariq Toukan's avatar Tariq Toukan Committed by David S. Miller
Browse files

net/mlx4_en: Refactor mlx4_en_free_tx_desc 



Some code re-ordering, functionally equivalent.

- The !tx_info->inl check is evaluated anyway in both flows
  (common case/end case). Run it first, this might finish
  the flows earlier.
- dma_unmap calls are identical in both flows, get it out
  of the if block into the common area.

Performance tests:
Tested on ConnectX3Pro, Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz

Gain is too small to be measurable, no degradation sensed.
Results are similar for IPv4 and IPv6.

Signed-off-by: default avatarTariq Toukan <tariqt@mellanox.com>
Reviewed-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
Cc: kernel-team@fb.com
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9573e0d3

drivers/net/ethernet/mellanox/mlx4/en_tx.c

+16 −29
Original line number Diff line number Diff line
@@ -289,9 +289,6 @@ u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv, 
		skb_tstamp_tx(skb, &hwts);

	}



	/* Optimize the common case when there are no wraparounds */

	if (likely((void *)tx_desc +

		   (tx_info->nr_txbb << LOG_TXBB_SIZE) <= end)) {

	if (!tx_info->inl) {

		if (tx_info->linear)

			dma_unmap_single(priv->ddev,
@@ -303,6 +300,9 @@ u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv, 
				       tx_info->map0_dma,

				       tx_info->map0_byte_count,

				       PCI_DMA_TODEVICE);

		/* Optimize the common case when there are no wraparounds */

		if (likely((void *)tx_desc +

			   (tx_info->nr_txbb << LOG_TXBB_SIZE) <= end)) {

			for (i = 1; i < nr_maps; i++) {

				data++;

				dma_unmap_page(priv->ddev,
@@ -310,23 +310,10 @@ u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv, 
					be32_to_cpu(data->byte_count),

					PCI_DMA_TODEVICE);

			}

		}

		} else {

		if (!tx_info->inl) {

			if ((void *) data >= end) {

			if ((void *)data >= end)

				data = ring->buf + ((void *)data - end);

			}



			if (tx_info->linear)

				dma_unmap_single(priv->ddev,

						tx_info->map0_dma,

						tx_info->map0_byte_count,

						PCI_DMA_TODEVICE);

			else

				dma_unmap_page(priv->ddev,

					       tx_info->map0_dma,

					       tx_info->map0_byte_count,

					       PCI_DMA_TODEVICE);

			for (i = 1; i < nr_maps; i++) {

				data++;

				/* Check for wraparound before unmapping */