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| author |   Eric Dumazet <eric.dumazet@gmail.com> | 2009-06-05 04:04:16 +0000 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2009-06-08 00:21:48 -0700 |
| commit | 042a53a9e437feaf2230dd2cadcecfae9c7bfe05 (patch) | |
| tree | ae9078f61e390a3014aecb3fe80d3438ab25ee51 /drivers/net/tg3.c | |
| parent | net: num_dma_maps is not used (diff) | |
| download | linux-dev-042a53a9e437feaf2230dd2cadcecfae9c7bfe05.tar.xz linux-dev-042a53a9e437feaf2230dd2cadcecfae9c7bfe05.zip | |
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.c | 10 |
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; |