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Message-ID: <4A2925E0.6060508@gmail.com>
Date: Fri, 05 Jun 2009 16:04:16 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: "David S. Miller" <davem@...emloft.net>
CC: Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH 2/2] 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@...il.com>
---
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/include/linux/skbuff.h b/include/linux/skbuff.h
index 7485058..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/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 5f7ba1a..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 de70a2d..fe55adc 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -4619,7 +4619,7 @@ 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;
@@ -4651,7 +4651,7 @@ 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/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);
}
}
--
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