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Commit 9ed318d5 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
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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: default avatarTom Herbert <therbert@google.com>
Acked-by: default avatarBruce Allan <bruce.w.allan@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4447957a

drivers/net/e1000e/e1000.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */

drivers/net/e1000e/netdev.c

+9 −9
Original line number Diff line number Diff line
@@ -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;