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authorEric Dumazet <eric.dumazet@gmail.com>2009-06-05 04:04:16 +0000
committerDavid S. Miller <davem@davemloft.net>2009-06-08 00:21:48 -0700
commit042a53a9e437feaf2230dd2cadcecfae9c7bfe05 (patch)
treeae9078f61e390a3014aecb3fe80d3438ab25ee51 /drivers/net/tg3.c
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/tg3.c')
-rw-r--r--drivers/net/tg3.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index a39b534fb43e..46a3f86125be 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -5021,7 +5021,7 @@ static int tigon3_dma_hwbug_workaround(struct tg3 *tp, struct sk_buff *skb,
/* New SKB is guaranteed to be linear. */
entry = *start;
ret = skb_dma_map(&tp->pdev->dev, new_skb, DMA_TO_DEVICE);
- new_addr = skb_shinfo(new_skb)->dma_maps[0];
+ new_addr = skb_shinfo(new_skb)->dma_head;
/* Make sure new skb does not cross any 4G boundaries.
* Drop the packet if it does.
@@ -5155,7 +5155,7 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
sp = skb_shinfo(skb);
- mapping = sp->dma_maps[0];
+ mapping = sp->dma_head;
tp->tx_buffers[entry].skb = skb;
@@ -5173,7 +5173,7 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
len = frag->size;
- mapping = sp->dma_maps[i + 1];
+ mapping = sp->dma_maps[i];
tp->tx_buffers[entry].skb = NULL;
tg3_set_txd(tp, entry, mapping, len,
@@ -5331,7 +5331,7 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev)
sp = skb_shinfo(skb);
- mapping = sp->dma_maps[0];
+ mapping = sp->dma_head;
tp->tx_buffers[entry].skb = skb;
@@ -5356,7 +5356,7 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev)
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
len = frag->size;
- mapping = sp->dma_maps[i + 1];
+ mapping = sp->dma_maps[i];
tp->tx_buffers[entry].skb = NULL;