From 042a53a9e437feaf2230dd2cadcecfae9c7bfe05 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 5 Jun 2009 04:04:16 +0000 Subject: [PATCH] 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/bnx2.c | 6 +++--- drivers/net/e1000/e1000_main.c | 4 ++-- drivers/net/e1000e/netdev.c | 4 ++-- drivers/net/igb/igb_main.c | 5 ++--- drivers/net/igbvf/netdev.c | 5 ++--- drivers/net/ixgb/ixgb_main.c | 4 ++-- drivers/net/ixgbe/ixgbe_main.c | 4 ++-- drivers/net/tg3.c | 10 +++++----- include/linux/skbuff.h | 5 ++++- net/core/skb_dma_map.c | 12 ++++++------ 10 files changed, 30 insertions(+), 29 deletions(-) diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c index f530172..391d2d4 100644 --- a/drivers/net/bnx2.c +++ b/drivers/net/bnx2.c @@ -5487,7 +5487,7 @@ bnx2_run_loopback(struct bnx2 *bp, int loopback_mode) dev_kfree_skb(skb); return -EIO; } - map = skb_shinfo(skb)->dma_maps[0]; + map = skb_shinfo(skb)->dma_head; REG_WR(bp, BNX2_HC_COMMAND, bp->hc_cmd | BNX2_HC_COMMAND_COAL_NOW_WO_INT); @@ -6167,7 +6167,7 @@ bnx2_start_xmit(struct sk_buff *skb, struct net_device *dev) } sp = skb_shinfo(skb); - mapping = sp->dma_maps[0]; + mapping = sp->dma_head; tx_buf = &txr->tx_buf_ring[ring_prod]; tx_buf->skb = skb; @@ -6191,7 +6191,7 @@ bnx2_start_xmit(struct sk_buff *skb, struct net_device *dev) txbd = &txr->tx_desc_ring[ring_prod]; len = frag->size; - mapping = sp->dma_maps[i + 1]; + mapping = sp->dma_maps[i]; txbd->tx_bd_haddr_hi = (u64) mapping >> 32; txbd->tx_bd_haddr_lo = (u64) mapping & 0xffffffff; diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c index 05e87a5..8d36743 100644 --- a/drivers/net/e1000/e1000_main.c +++ b/drivers/net/e1000/e1000_main.c @@ -2998,7 +2998,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter, size -= 4; buffer_info->length = size; - buffer_info->dma = map[0] + offset; + buffer_info->dma = skb_shinfo(skb)->dma_head + offset; buffer_info->time_stamp = jiffies; buffer_info->next_to_watch = i; @@ -3039,7 +3039,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter, size -= 4; buffer_info->length = size; - buffer_info->dma = map[f + 1] + offset; + buffer_info->dma = map[f] + offset; buffer_info->time_stamp = jiffies; buffer_info->next_to_watch = i; diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c index 38694c7..9043f1b 100644 --- a/drivers/net/e1000e/netdev.c +++ b/drivers/net/e1000e/netdev.c @@ -3916,7 +3916,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter, buffer_info->length = size; buffer_info->time_stamp = jiffies; buffer_info->next_to_watch = i; - buffer_info->dma = map[0] + offset; + buffer_info->dma = skb_shinfo(skb)->dma_head + offset; count++; len -= size; @@ -3947,7 +3947,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter, buffer_info->length = size; buffer_info->time_stamp = jiffies; buffer_info->next_to_watch = i; - buffer_info->dma = map[f + 1] + offset; + buffer_info->dma = map[f] + offset; len -= size; offset += size; diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c index 958b287..ea17319 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, /* set time_stamp *before* dma to help avoid a possible race */ buffer_info->time_stamp = jiffies; buffer_info->next_to_watch = i; - buffer_info->dma = map[count]; - count++; + buffer_info->dma = skb_shinfo(skb)->dma_head; for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) { struct skb_frag_struct *frag; @@ -3164,7 +3163,7 @@ static inline int igb_tx_map_adv(struct igb_adapter *adapter, tx_ring->buffer_info[i].skb = skb; tx_ring->buffer_info[first].next_to_watch = i; - return count; + return count + 1; } static inline void igb_tx_queue_adv(struct igb_adapter *adapter, diff --git a/drivers/net/igbvf/netdev.c b/drivers/net/igbvf/netdev.c index 5f7ba1a4..22aadb7 100644 --- a/drivers/net/igbvf/netdev.c +++ b/drivers/net/igbvf/netdev.c @@ -2119,8 +2119,7 @@ static inline int igbvf_tx_map_adv(struct igbvf_adapter *adapter, /* set time_stamp *before* dma to help avoid a possible race */ buffer_info->time_stamp = jiffies; buffer_info->next_to_watch = i; - buffer_info->dma = map[count]; - count++; + buffer_info->dma = skb_shinfo(skb)->dma_head; for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) { struct skb_frag_struct *frag; @@ -2144,7 +2143,7 @@ static inline int igbvf_tx_map_adv(struct igbvf_adapter *adapter, tx_ring->buffer_info[i].skb = skb; tx_ring->buffer_info[first].next_to_watch = i; - return count; + return count + 1; } static inline void igbvf_tx_queue_adv(struct igbvf_adapter *adapter, diff --git a/drivers/net/ixgb/ixgb_main.c b/drivers/net/ixgb/ixgb_main.c index 6eb7f37..9c897cf 100644 --- a/drivers/net/ixgb/ixgb_main.c +++ b/drivers/net/ixgb/ixgb_main.c @@ -1300,7 +1300,7 @@ ixgb_tx_map(struct ixgb_adapter *adapter, struct sk_buff *skb, buffer_info->length = size; WARN_ON(buffer_info->dma != 0); buffer_info->time_stamp = jiffies; - buffer_info->dma = map[0] + offset; + buffer_info->dma = skb_shinfo(skb)->dma_head + offset; pci_map_single(adapter->pdev, skb->data + offset, size, @@ -1340,7 +1340,7 @@ ixgb_tx_map(struct ixgb_adapter *adapter, struct sk_buff *skb, buffer_info->length = size; buffer_info->time_stamp = jiffies; - buffer_info->dma = map[f + 1] + offset; + buffer_info->dma = map[f] + offset; buffer_info->next_to_watch = 0; len -= size; diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c index d36003c..09994e9 100644 --- a/drivers/net/ixgbe/ixgbe_main.c +++ b/drivers/net/ixgbe/ixgbe_main.c @@ -4837,7 +4837,7 @@ static int ixgbe_tx_map(struct ixgbe_adapter *adapter, size = min(len, (uint)IXGBE_MAX_DATA_PER_TXD); tx_buffer_info->length = size; - tx_buffer_info->dma = map[0] + offset; + tx_buffer_info->dma = skb_shinfo(skb)->dma_head + offset; tx_buffer_info->time_stamp = jiffies; tx_buffer_info->next_to_watch = i; @@ -4869,7 +4869,7 @@ static int ixgbe_tx_map(struct ixgbe_adapter *adapter, size = min(len, (uint)IXGBE_MAX_DATA_PER_TXD); tx_buffer_info->length = size; - tx_buffer_info->dma = map[f + 1] + offset; + tx_buffer_info->dma = map[f] + offset; tx_buffer_info->time_stamp = jiffies; tx_buffer_info->next_to_watch = i; diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c index a39b534..46a3f86 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; diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 74850581..aad484c 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -189,6 +189,9 @@ struct skb_shared_info { atomic_t dataref; unsigned short nr_frags; unsigned short gso_size; +#ifdef CONFIG_HAS_DMA + dma_addr_t dma_head; +#endif /* Warning: this field is not always filled in (UFO)! */ unsigned short gso_segs; unsigned short gso_type; @@ -198,7 +201,7 @@ struct skb_shared_info { struct skb_shared_hwtstamps hwtstamps; skb_frag_t frags[MAX_SKB_FRAGS]; #ifdef CONFIG_HAS_DMA - dma_addr_t dma_maps[MAX_SKB_FRAGS + 1]; + dma_addr_t dma_maps[MAX_SKB_FRAGS]; #endif /* Intermediate layers must ensure that destructor_arg * remains valid until skb destructor */ diff --git a/net/core/skb_dma_map.c b/net/core/skb_dma_map.c index 7adb623..79687df 100644 --- a/net/core/skb_dma_map.c +++ b/net/core/skb_dma_map.c @@ -20,7 +20,7 @@ int skb_dma_map(struct device *dev, struct sk_buff *skb, if (dma_mapping_error(dev, map)) goto out_err; - sp->dma_maps[0] = map; + sp->dma_head = map; for (i = 0; i < sp->nr_frags; i++) { skb_frag_t *fp = &sp->frags[i]; @@ -28,7 +28,7 @@ int skb_dma_map(struct device *dev, struct sk_buff *skb, fp->size, dir); if (dma_mapping_error(dev, map)) goto unwind; - sp->dma_maps[i + 1] = map; + sp->dma_maps[i] = map; } return 0; @@ -37,10 +37,10 @@ unwind: while (--i >= 0) { skb_frag_t *fp = &sp->frags[i]; - dma_unmap_page(dev, sp->dma_maps[i + 1], + dma_unmap_page(dev, sp->dma_maps[i], fp->size, dir); } - dma_unmap_single(dev, sp->dma_maps[0], + dma_unmap_single(dev, sp->dma_head, skb_headlen(skb), dir); out_err: return -ENOMEM; @@ -53,12 +53,12 @@ void skb_dma_unmap(struct device *dev, struct sk_buff *skb, struct skb_shared_info *sp = skb_shinfo(skb); int i; - dma_unmap_single(dev, sp->dma_maps[0], + dma_unmap_single(dev, sp->dma_head, skb_headlen(skb), dir); for (i = 0; i < sp->nr_frags; i++) { skb_frag_t *fp = &sp->frags[i]; - dma_unmap_page(dev, sp->dma_maps[i + 1], + dma_unmap_page(dev, sp->dma_maps[i], fp->size, dir); } } -- 2.7.4