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igb: Improve performance and reduce size of igb_tx_map 

This change is meant to both improve the performance and reduce the size of
igb_tx_map.  To do this I have expanded the work done in the main loop by
pushing first into tx_buffer.  This allows us to pull in the dma_mapping_error
check, the tx_buffer value assignment, and the initial DMA value assignment to
the Tx descriptor.  The net result is that the function reduces in size by a
little over a 100 bytes and is about 1% or 2% faster.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2012-11-13 04:03:24 +00:00 committed by David S. Miller
parent 1d9daf45b4
commit 80d0759e5e
1 changed files with 22 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
drivers/net/ethernet/intel/igb/igb_main.c
View File

@ -4188,29 +4188,34 @@ static void igb_tx_map(struct igb_ring *tx_ring,
struct sk_buff *skb = first->skb;
struct igb_tx_buffer *tx_buffer;
union e1000_adv_tx_desc *tx_desc;
struct skb_frag_struct *frag;
dma_addr_t dma;
struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
unsigned int data_len = skb->data_len;
unsigned int size = skb_headlen(skb);
unsigned int paylen = skb->len - hdr_len;
unsigned int data_len, size;
u32 tx_flags = first->tx_flags;
u32 cmd_type = igb_tx_cmd_type(skb, tx_flags);
u16 i = tx_ring->next_to_use;
tx_desc = IGB_TX_DESC(tx_ring, i);
igb_tx_olinfo_status(tx_ring, tx_desc, tx_flags, paylen);
igb_tx_olinfo_status(tx_ring, tx_desc, tx_flags, skb->len - hdr_len);
size = skb_headlen(skb);
data_len = skb->data_len;
dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
if (dma_mapping_error(tx_ring->dev, dma))
goto dma_error;
/* record length, and DMA address */
dma_unmap_len_set(first, len, size);
dma_unmap_addr_set(first, dma, dma);
tx_desc->read.buffer_addr = cpu_to_le64(dma);
tx_buffer = first;
for (frag = &skb_shinfo(skb)->frags[0];; frag++) {
if (dma_mapping_error(tx_ring->dev, dma))
goto dma_error;
/* record length, and DMA address */
dma_unmap_len_set(tx_buffer, len, size);
dma_unmap_addr_set(tx_buffer, dma, dma);
tx_desc->read.buffer_addr = cpu_to_le64(dma);
for (;;) {
while (unlikely(size > IGB_MAX_DATA_PER_TXD)) {
tx_desc->read.cmd_type_len =
cpu_to_le32(cmd_type ^ IGB_MAX_DATA_PER_TXD);
@ -4221,11 +4226,11 @@ static void igb_tx_map(struct igb_ring *tx_ring,
tx_desc = IGB_TX_DESC(tx_ring, 0);
i = 0;
}
tx_desc->read.olinfo_status = 0;
dma += IGB_MAX_DATA_PER_TXD;
size -= IGB_MAX_DATA_PER_TXD;
tx_desc->read.olinfo_status = 0;
tx_desc->read.buffer_addr = cpu_to_le64(dma);
}
@ -4240,31 +4245,23 @@ static void igb_tx_map(struct igb_ring *tx_ring,
tx_desc = IGB_TX_DESC(tx_ring, 0);
i = 0;
}
tx_desc->read.olinfo_status = 0;
size = skb_frag_size(frag);
data_len -= size;
dma = skb_frag_dma_map(tx_ring->dev, frag, 0,
size, DMA_TO_DEVICE);
if (dma_mapping_error(tx_ring->dev, dma))
goto dma_error;
size, DMA_TO_DEVICE);
tx_buffer = &tx_ring->tx_buffer_info[i];
dma_unmap_len_set(tx_buffer, len, size);
dma_unmap_addr_set(tx_buffer, dma, dma);
tx_desc->read.olinfo_status = 0;
tx_desc->read.buffer_addr = cpu_to_le64(dma);
frag++;
}
netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);
/* write last descriptor with RS and EOP bits */
cmd_type |= size | IGB_TXD_DCMD;
tx_desc->read.cmd_type_len = cpu_to_le32(cmd_type);
netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);
/* set the timestamp */
first->time_stamp = jiffies;