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net/mlx4_en: Saving mem access on data path
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Localized the pdev->dev, and using dma_map instead of pci_map
There are multiple map/unmap operations on data path,
optimizing those by saving redundant pointer access.
Those places were identified as hot-spots when running kernel profiling
during some benchmarks.
The fixes had most impact when testing packet rate with small packets,
reducing several % from CPU load, and in some case being the difference
between reaching wire speed or being CPU bound.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Yevgeny Petrilin authored and David S. Miller committed Mar 6, 2012
1 parent 6975f4c commit ebf8c9a
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Showing 4 changed files with 13 additions and 16 deletions.
1 change: 1 addition & 0 deletions drivers/net/ethernet/mellanox/mlx4/en_netdev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1062,6 +1062,7 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
memset(priv, 0, sizeof(struct mlx4_en_priv));
priv->dev = dev;
priv->mdev = mdev;
priv->ddev = &mdev->pdev->dev;
priv->prof = prof;
priv->port = port;
priv->port_up = false;
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14 changes: 5 additions & 9 deletions drivers/net/ethernet/mellanox/mlx4/en_rx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,6 @@ static int mlx4_en_alloc_frag(struct mlx4_en_priv *priv,
struct mlx4_en_rx_alloc *ring_alloc,
int i)
{
struct mlx4_en_dev *mdev = priv->mdev;
struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
struct mlx4_en_rx_alloc *page_alloc = &ring_alloc[i];
struct page *page;
Expand All @@ -72,7 +71,7 @@ static int mlx4_en_alloc_frag(struct mlx4_en_priv *priv,
skb_frags[i].offset = page_alloc->offset;
page_alloc->offset += frag_info->frag_stride;
}
dma = pci_map_single(mdev->pdev, page_address(skb_frags[i].page) +
dma = dma_map_single(priv->ddev, page_address(skb_frags[i].page) +
skb_frags[i].offset, frag_info->frag_size,
PCI_DMA_FROMDEVICE);
rx_desc->data[i].addr = cpu_to_be64(dma);
Expand Down Expand Up @@ -186,7 +185,6 @@ static void mlx4_en_free_rx_desc(struct mlx4_en_priv *priv,
struct mlx4_en_rx_ring *ring,
int index)
{
struct mlx4_en_dev *mdev = priv->mdev;
struct page_frag *skb_frags;
struct mlx4_en_rx_desc *rx_desc = ring->buf + (index << ring->log_stride);
dma_addr_t dma;
Expand All @@ -198,7 +196,7 @@ static void mlx4_en_free_rx_desc(struct mlx4_en_priv *priv,
dma = be64_to_cpu(rx_desc->data[nr].addr);

en_dbg(DRV, priv, "Unmapping buffer at dma:0x%llx\n", (u64) dma);
pci_unmap_single(mdev->pdev, dma, skb_frags[nr].size,
dma_unmap_single(priv->ddev, dma, skb_frags[nr].size,
PCI_DMA_FROMDEVICE);
put_page(skb_frags[nr].page);
}
Expand Down Expand Up @@ -412,7 +410,6 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
int length)
{
struct skb_frag_struct *skb_frags_rx = skb_shinfo(skb)->frags;
struct mlx4_en_dev *mdev = priv->mdev;
struct mlx4_en_frag_info *frag_info;
int nr;
dma_addr_t dma;
Expand All @@ -435,7 +432,7 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
goto fail;

/* Unmap buffer */
pci_unmap_single(mdev->pdev, dma, skb_frag_size(&skb_frags_rx[nr]),
dma_unmap_single(priv->ddev, dma, skb_frag_size(&skb_frags_rx[nr]),
PCI_DMA_FROMDEVICE);
}
/* Adjust size of last fragment to match actual length */
Expand All @@ -461,7 +458,6 @@ static struct sk_buff *mlx4_en_rx_skb(struct mlx4_en_priv *priv,
struct mlx4_en_rx_alloc *page_alloc,
unsigned int length)
{
struct mlx4_en_dev *mdev = priv->mdev;
struct sk_buff *skb;
void *va;
int used_frags;
Expand All @@ -483,10 +479,10 @@ static struct sk_buff *mlx4_en_rx_skb(struct mlx4_en_priv *priv,
/* We are copying all relevant data to the skb - temporarily
* synch buffers for the copy */
dma = be64_to_cpu(rx_desc->data[0].addr);
dma_sync_single_for_cpu(&mdev->pdev->dev, dma, length,
dma_sync_single_for_cpu(priv->ddev, dma, length,
DMA_FROM_DEVICE);
skb_copy_to_linear_data(skb, va, length);
dma_sync_single_for_device(&mdev->pdev->dev, dma, length,
dma_sync_single_for_device(priv->ddev, dma, length,
DMA_FROM_DEVICE);
skb->tail += length;
} else {
Expand Down
13 changes: 6 additions & 7 deletions drivers/net/ethernet/mellanox/mlx4/en_tx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -198,7 +198,6 @@ static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
struct mlx4_en_tx_ring *ring,
int index, u8 owner)
{
struct mlx4_en_dev *mdev = priv->mdev;
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_wqe_data_seg *data = (void *) tx_desc + tx_info->data_offset;
Expand All @@ -214,7 +213,7 @@ static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
if (likely((void *) tx_desc + tx_info->nr_txbb * TXBB_SIZE <= end)) {
if (!tx_info->inl) {
if (tx_info->linear) {
pci_unmap_single(mdev->pdev,
dma_unmap_single(priv->ddev,
(dma_addr_t) be64_to_cpu(data->addr),
be32_to_cpu(data->byte_count),
PCI_DMA_TODEVICE);
Expand All @@ -223,7 +222,7 @@ static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,

for (i = 0; i < frags; i++) {
frag = &skb_shinfo(skb)->frags[i];
pci_unmap_page(mdev->pdev,
dma_unmap_page(priv->ddev,
(dma_addr_t) be64_to_cpu(data[i].addr),
skb_frag_size(frag), PCI_DMA_TODEVICE);
}
Expand All @@ -241,7 +240,7 @@ static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
}

if (tx_info->linear) {
pci_unmap_single(mdev->pdev,
dma_unmap_single(priv->ddev,
(dma_addr_t) be64_to_cpu(data->addr),
be32_to_cpu(data->byte_count),
PCI_DMA_TODEVICE);
Expand All @@ -253,7 +252,7 @@ static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
if ((void *) data >= end)
data = ring->buf;
frag = &skb_shinfo(skb)->frags[i];
pci_unmap_page(mdev->pdev,
dma_unmap_page(priv->ddev,
(dma_addr_t) be64_to_cpu(data->addr),
skb_frag_size(frag), PCI_DMA_TODEVICE);
++data;
Expand Down Expand Up @@ -733,7 +732,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
/* Map fragments */
for (i = skb_shinfo(skb)->nr_frags - 1; i >= 0; i--) {
frag = &skb_shinfo(skb)->frags[i];
dma = skb_frag_dma_map(&mdev->dev->pdev->dev, frag,
dma = skb_frag_dma_map(priv->ddev, frag,
0, skb_frag_size(frag),
DMA_TO_DEVICE);
data->addr = cpu_to_be64(dma);
Expand All @@ -745,7 +744,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)

/* Map linear part */
if (tx_info->linear) {
dma = pci_map_single(mdev->dev->pdev, skb->data + lso_header_size,
dma = dma_map_single(priv->ddev, skb->data + lso_header_size,
skb_headlen(skb) - lso_header_size, PCI_DMA_TODEVICE);
data->addr = cpu_to_be64(dma);
data->lkey = cpu_to_be32(mdev->mr.key);
Expand Down
1 change: 1 addition & 0 deletions drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -482,6 +482,7 @@ struct mlx4_en_priv {
struct mlx4_en_stat_out_mbox hw_stats;
int vids[128];
bool wol;
struct device *ddev;
};

enum mlx4_en_wol {
Expand Down

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