From 042a53a9e437feaf2230dd2cadcecfae9c7bfe05 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 5 Jun 2009 04:04:16 +0000 Subject: 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 Signed-off-by: David S. Miller --- drivers/net/tg3.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'drivers/net/tg3.c') diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c index a39b534fb43..46a3f86125b 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; -- cgit v1.2.3-70-g09d2