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e1000e: save skb counts in TX to avoid cache misses 

In e1000_tx_map, precompute number of segements and bytecounts which
are derived from fields in skb; these are stored in buffer_info.  When
cleaning tx in e1000_clean_tx_irq use the values in the associated
buffer_info for statistics counting, this eliminates cache misses
on skb fields.

Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Bruce Allan <bruce.w.allan@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:
Tom Herbert 2010-05-05 14:02:27 +00:00 committed by David S. Miller
parent 4447957a82
commit 9ed318d546
2 changed files with 11 additions and 9 deletions
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2
drivers/net/e1000e/e1000.h
View File

@ -189,6 +189,8 @@ struct e1000_buffer {
unsigned long time_stamp;
u16 length;
u16 next_to_watch;
unsigned int segs;
unsigned int bytecount;
u16 mapped_as_page;
};
/* Rx */

18
drivers/net/e1000e/netdev.c
View File

@ -1001,14 +1001,8 @@ static bool e1000_clean_tx_irq(struct e1000_adapter *adapter)
cleaned = (i == eop);
if (cleaned) {
struct sk_buff *skb = buffer_info->skb;
unsigned int segs, bytecount;
segs = skb_shinfo(skb)->gso_segs ?: 1;
/* multiply data chunks by size of headers */
bytecount = ((segs - 1) * skb_headlen(skb)) +
skb->len;
total_tx_packets += segs;
total_tx_bytes += bytecount;
total_tx_packets += buffer_info->segs;
total_tx_bytes += buffer_info->bytecount;
}
e1000_put_txbuf(adapter, buffer_info);
@ -4261,7 +4255,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
struct e1000_buffer *buffer_info;
unsigned int len = skb_headlen(skb);
unsigned int offset = 0, size, count = 0, i;
unsigned int f;
unsigned int f, bytecount, segs;
i = tx_ring->next_to_use;
@ -4321,7 +4315,13 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
}
}
segs = skb_shinfo(skb)->gso_segs ?: 1;
/* multiply data chunks by size of headers */
bytecount = ((segs - 1) * skb_headlen(skb)) + skb->len;
tx_ring->buffer_info[i].skb = skb;
tx_ring->buffer_info[i].segs = segs;
tx_ring->buffer_info[i].bytecount = bytecount;
tx_ring->buffer_info[first].next_to_watch = i;
return count;