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[SK_BUFF]: Convert skb->tail to sk_buff_data_t

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So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arnaldo Carvalho de Melo
2007-04-19 20:29:13 -07:00
committed by David S. Miller
parent be8bd86321
commit 27a884dc3c
110 changed files with 396 additions and 329 deletions
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4
drivers/net/e1000/e1000_main.c
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@@ -3304,7 +3304,7 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
* NOTE: this is a TSO only workaround
* if end byte alignment not correct move us
* into the next dword */
if ((unsigned long)(skb->tail - 1) & 4)
if ((unsigned long)(skb_tail_pointer(skb) - 1) & 4)
break;
/* fall through */
case e1000_82571:
@@ -4388,7 +4388,7 @@ e1000_clean_rx_irq_ps(struct e1000_adapter *adapter,
PCI_DMA_FROMDEVICE);
vaddr = kmap_atomic(ps_page->ps_page[0],
KM_SKB_DATA_SOFTIRQ);
memcpy(skb->tail, vaddr, l1);
memcpy(skb_tail_pointer(skb), vaddr, l1);
kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
pci_dma_sync_single_for_device(pdev,
ps_page_dma->ps_page_dma[0],