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authorEric Dumazet <eric.dumazet@gmail.com>2009-06-05 00:04:16 -0400
committerDavid S. Miller <davem@davemloft.net>2009-06-08 03:21:48 -0400
commit042a53a9e437feaf2230dd2cadcecfae9c7bfe05 (patch)
treeae9078f61e390a3014aecb3fe80d3438ab25ee51 /drivers/net/igb
parenteae3f29cc73f83cc3f1891d3ad40021b5172c630 (diff)
net: skb_shared_info optimization
skb_dma_unmap() is quite expensive for small packets, because we use two different cache lines from skb_shared_info. One to access nr_frags, one to access dma_maps[0] Instead of dma_maps being an array of MAX_SKB_FRAGS + 1 elements, let dma_head alone in a new dma_head field, close to nr_frags, to reduce cache lines misses. Tested on my dev machine (bnx2 & tg3 adapters), nice speedup ! Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/igb')
-rw-r--r--drivers/net/igb/igb_main.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 958b2879da48..ea17319624aa 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -3139,8 +3139,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
3139 /* set time_stamp *before* dma to help avoid a possible race */ 3139 /* set time_stamp *before* dma to help avoid a possible race */
3140 buffer_info->time_stamp = jiffies; 3140 buffer_info->time_stamp = jiffies;
3141 buffer_info->next_to_watch = i; 3141 buffer_info->next_to_watch = i;
3142 buffer_info->dma = map[count]; 3142 buffer_info->dma = skb_shinfo(skb)->dma_head;
3143 count++;
3144 3143
3145 for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) { 3144 for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) {
3146 struct skb_frag_struct *frag; 3145 struct skb_frag_struct *frag;
@@ -3164,7 +3163,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter,
3164 tx_ring->buffer_info[i].skb = skb; 3163 tx_ring->buffer_info[i].skb = skb;
3165 tx_ring->buffer_info[first].next_to_watch = i; 3164 tx_ring->buffer_info[first].next_to_watch = i;
3166 3165
3167 return count; 3166 return count + 1;
3168} 3167}
3169 3168
3170static inline void igb_tx_queue_adv(struct igb_adapter *adapter, 3169static inline void igb_tx_queue_adv(struct igb_adapter *adapter,