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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 <tariqt@mellanox.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Cc: kernel-team@fb.com
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tariq Toukan 2017-06-15 14:35:39 +03:00 committed by David S. Miller
parent 77788b5bf6
commit 9573e0d39f
2 changed files with 16 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
drivers/net/ethernet/mellanox/mlx4/en_tx.c
View File

@ -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;

3
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
View File

@ -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)