From 9573e0d39ff8d7d1e0bcc10e23d18b9cbc4ca14e Mon Sep 17 00:00:00 2001 From: Tariq Toukan Date: Thu, 15 Jun 2017 14:35:39 +0300 Subject: [PATCH] net/mlx4_en: Replace TXBB_SIZE multiplications with shift operations Define LOG_TXBB_SIZE, log of TXBB_SIZE, and use it with a shift operation instead of a multiplication with TXBB_SIZE. Operations are equivalent as TXBB_SIZE is a power of two. 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: Tariq Toukan Reviewed-by: Saeed Mahameed Cc: kernel-team@fb.com Cc: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/en_tx.c | 26 +++++++++++--------- drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 3 ++- 2 files changed, 16 insertions(+), 13 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index 500442c60342..efc4411b1e44 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -234,23 +234,24 @@ static void mlx4_en_stamp_wqe(struct mlx4_en_priv *priv, u8 owner) { __be32 stamp = cpu_to_be32(STAMP_VAL | (!!owner << STAMP_SHIFT)); - struct mlx4_en_tx_desc *tx_desc = ring->buf + index * TXBB_SIZE; + struct mlx4_en_tx_desc *tx_desc = ring->buf + (index << LOG_TXBB_SIZE); struct mlx4_en_tx_info *tx_info = &ring->tx_info[index]; void *end = ring->buf + ring->buf_size; __be32 *ptr = (__be32 *)tx_desc; int i; /* Optimize the common case when there are no wraparounds */ - if (likely((void *)tx_desc + tx_info->nr_txbb * TXBB_SIZE <= end)) { + if (likely((void *)tx_desc + + (tx_info->nr_txbb << LOG_TXBB_SIZE) <= end)) { /* Stamp the freed descriptor */ - for (i = 0; i < tx_info->nr_txbb * TXBB_SIZE; + for (i = 0; i < tx_info->nr_txbb << LOG_TXBB_SIZE; i += STAMP_STRIDE) { *ptr = stamp; ptr += STAMP_DWORDS; } } else { /* Stamp the freed descriptor */ - for (i = 0; i < tx_info->nr_txbb * TXBB_SIZE; + for (i = 0; i < tx_info->nr_txbb << LOG_TXBB_SIZE; i += STAMP_STRIDE) { *ptr = stamp; ptr += STAMP_DWORDS; @@ -269,7 +270,7 @@ u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv, int napi_mode) { struct mlx4_en_tx_info *tx_info = &ring->tx_info[index]; - struct mlx4_en_tx_desc *tx_desc = ring->buf + index * TXBB_SIZE; + struct mlx4_en_tx_desc *tx_desc = ring->buf + (index << LOG_TXBB_SIZE); struct mlx4_wqe_data_seg *data = (void *) tx_desc + tx_info->data_offset; void *end = ring->buf + ring->buf_size; struct sk_buff *skb = tx_info->skb; @@ -289,7 +290,8 @@ u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv, } /* Optimize the common case when there are no wraparounds */ - if (likely((void *) tx_desc + tx_info->nr_txbb * TXBB_SIZE <= end)) { + 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, @@ -542,7 +544,7 @@ static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv, u32 index, unsigned int desc_size) { - u32 copy = (ring->size - index) * TXBB_SIZE; + u32 copy = (ring->size - index) << LOG_TXBB_SIZE; int i; for (i = desc_size - copy - 4; i >= 0; i -= 4) { @@ -557,12 +559,12 @@ static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv, if ((i & (TXBB_SIZE - 1)) == 0) wmb(); - *((u32 *) (ring->buf + index * TXBB_SIZE + i)) = + *((u32 *)(ring->buf + (index << LOG_TXBB_SIZE) + i)) = *((u32 *) (ring->bounce_buf + i)); } /* Return real descriptor location */ - return ring->buf + index * TXBB_SIZE; + return ring->buf + (index << LOG_TXBB_SIZE); } /* Decide if skb can be inlined in tx descriptor to avoid dma mapping @@ -881,7 +883,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) /* Align descriptor to TXBB size */ desc_size = ALIGN(real_size, TXBB_SIZE); - nr_txbb = desc_size / TXBB_SIZE; + nr_txbb = desc_size >> LOG_TXBB_SIZE; if (unlikely(nr_txbb > MAX_DESC_TXBBS)) { if (netif_msg_tx_err(priv)) en_warn(priv, "Oversized header or SG list\n"); @@ -916,7 +918,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) /* See if we have enough space for whole descriptor TXBB for setting * SW ownership on next descriptor; if not, use a bounce buffer. */ if (likely(index + nr_txbb <= ring->size)) - tx_desc = ring->buf + index * TXBB_SIZE; + tx_desc = ring->buf + (index << LOG_TXBB_SIZE); else { tx_desc = (struct mlx4_en_tx_desc *) ring->bounce_buf; bounce = true; @@ -1129,7 +1131,7 @@ netdev_tx_t mlx4_en_xmit_frame(struct mlx4_en_rx_ring *rx_ring, AVG_PERF_COUNTER(priv->pstats.inflight_avg, (u32)(ring->prod - READ_ONCE(ring->cons) - 1)); - tx_desc = ring->buf + index * TXBB_SIZE; + tx_desc = ring->buf + (index << LOG_TXBB_SIZE); data = &tx_desc->data; dma = frame->dma; diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h index 7f61b5829709..963b77d51b48 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h @@ -72,7 +72,8 @@ #define DEF_RX_RINGS 16 #define MAX_RX_RINGS 128 #define MIN_RX_RINGS 4 -#define TXBB_SIZE 64 +#define LOG_TXBB_SIZE 6 +#define TXBB_SIZE BIT(LOG_TXBB_SIZE) #define HEADROOM (2048 / TXBB_SIZE + 1) #define STAMP_STRIDE 64 #define STAMP_DWORDS (STAMP_STRIDE / 4) -- 2.20.1