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igb: use buffer_info->dma instead of shinfo->nr_frags to determine unmap

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This change makes it so that we use buffer_info->dma instead of
shinfo->nr_frags to determine if we need to unmap a received skb.  By doing
this we can avoid a cache miss on small packets since the buffer_info
structure should already be prefetched.

Signed-off-by: Alexander Duyck <alexander.h.duyck@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 2009-07-23 18:10:06 +00:00 committed by David S. Miller
parent 4703bf73bd
commit 2d94d8ab76
1 changed files with 18 additions and 12 deletions
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30
drivers/net/igb/igb_main.c
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@ -4538,6 +4538,20 @@ static inline void igb_rx_checksum_adv(struct igb_adapter *adapter,
adapter->hw_csum_good++;
}
static inline u16 igb_get_hlen(struct igb_adapter *adapter,
union e1000_adv_rx_desc *rx_desc)
{
/* HW will not DMA in data larger than the given buffer, even if it
* parses the (NFS, of course) header to be larger. In that case, it
* fills the header buffer and spills the rest into the page.
*/
u16 hlen = (le16_to_cpu(rx_desc->wb.lower.lo_dword.hdr_info) &
E1000_RXDADV_HDRBUFLEN_MASK) >> E1000_RXDADV_HDRBUFLEN_SHIFT;
if (hlen > adapter->rx_ps_hdr_size)
hlen = adapter->rx_ps_hdr_size;
return hlen;
}
static bool igb_clean_rx_irq_adv(struct igb_ring *rx_ring,
int *work_done, int budget)
{
@ -4552,7 +4566,8 @@ static bool igb_clean_rx_irq_adv(struct igb_ring *rx_ring,
int cleaned_count = 0;
unsigned int total_bytes = 0, total_packets = 0;
unsigned int i;
u32 length, hlen, staterr;
u32 staterr;
u16 length;
i = rx_ring->next_to_clean;
buffer_info = &rx_ring->buffer_info[i];
@ -4589,17 +4604,8 @@ static bool igb_clean_rx_irq_adv(struct igb_ring *rx_ring,
goto send_up;
}
/* HW will not DMA in data larger than the given buffer, even
* if it parses the (NFS, of course) header to be larger. In
* that case, it fills the header buffer and spills the rest
* into the page.
*/
hlen = (le16_to_cpu(rx_desc->wb.lower.lo_dword.hdr_info) &
E1000_RXDADV_HDRBUFLEN_MASK) >> E1000_RXDADV_HDRBUFLEN_SHIFT;
if (hlen > adapter->rx_ps_hdr_size)
hlen = adapter->rx_ps_hdr_size;
if (!skb_shinfo(skb)->nr_frags) {
if (buffer_info->dma) {
u16 hlen = igb_get_hlen(adapter, rx_desc);
pci_unmap_single(pdev, buffer_info->dma,
adapter->rx_ps_hdr_size,
PCI_DMA_FROMDEVICE);