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sky2: optimize transmit completion
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Don't reference the list element in hardware transmit ring on transmit
completion. The list element is updated by hardware, therefore
it causes a cache miss. Do book keeping in software structure.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Stephen Hemminger authored and David S. Miller committed Aug 19, 2009
1 parent ee5f68f commit 6b84dac
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Showing 2 changed files with 34 additions and 49 deletions.
80 changes: 31 additions & 49 deletions drivers/net/sky2.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1001,8 +1001,11 @@ static void sky2_prefetch_init(struct sky2_hw *hw, u32 qaddr,
static inline struct sky2_tx_le *get_tx_le(struct sky2_port *sky2, u16 *slot)
{
struct sky2_tx_le *le = sky2->tx_le + *slot;
struct tx_ring_info *re = sky2->tx_ring + *slot;

*slot = RING_NEXT(*slot, sky2->tx_ring_size);
re->flags = 0;
re->skb = NULL;
le->ctrl = 0;
return le;
}
Expand All @@ -1021,12 +1024,6 @@ static void tx_init(struct sky2_port *sky2)
sky2->tx_last_upper = 0;
}

static inline struct tx_ring_info *tx_le_re(struct sky2_port *sky2,
struct sky2_tx_le *le)
{
return sky2->tx_ring + (le - sky2->tx_le);
}

/* Update chip's next pointer */
static inline void sky2_put_idx(struct sky2_hw *hw, unsigned q, u16 idx)
{
Expand Down Expand Up @@ -1563,6 +1560,19 @@ static unsigned tx_le_req(const struct sk_buff *skb)
return count;
}

static void sky2_tx_unmap(struct pci_dev *pdev,
const struct tx_ring_info *re)
{
if (re->flags & TX_MAP_SINGLE)
pci_unmap_single(pdev, pci_unmap_addr(re, mapaddr),
pci_unmap_len(re, maplen),
PCI_DMA_TODEVICE);
else if (re->flags & TX_MAP_PAGE)
pci_unmap_page(pdev, pci_unmap_addr(re, mapaddr),
pci_unmap_len(re, maplen),
PCI_DMA_TODEVICE);
}

/*
* Put one packet in ring for transmit.
* A single packet can generate multiple list elements, and
Expand Down Expand Up @@ -1667,16 +1677,17 @@ static int sky2_xmit_frame(struct sk_buff *skb, struct net_device *dev)
}
}

re = sky2->tx_ring + slot;
re->flags = TX_MAP_SINGLE;
pci_unmap_addr_set(re, mapaddr, mapping);
pci_unmap_len_set(re, maplen, len);

le = get_tx_le(sky2, &slot);
le->addr = cpu_to_le32(lower_32_bits(mapping));
le->length = cpu_to_le16(len);
le->ctrl = ctrl;
le->opcode = mss ? (OP_LARGESEND | HW_OWNER) : (OP_PACKET | HW_OWNER);

re = tx_le_re(sky2, le);
re->skb = skb;
pci_unmap_addr_set(re, mapaddr, mapping);
pci_unmap_len_set(re, maplen, len);

for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
Expand All @@ -1695,18 +1706,19 @@ static int sky2_xmit_frame(struct sk_buff *skb, struct net_device *dev)
le->opcode = OP_ADDR64 | HW_OWNER;
}

re = sky2->tx_ring + slot;
re->flags = TX_MAP_PAGE;
pci_unmap_addr_set(re, mapaddr, mapping);
pci_unmap_len_set(re, maplen, frag->size);

le = get_tx_le(sky2, &slot);
le->addr = cpu_to_le32(lower_32_bits(mapping));
le->length = cpu_to_le16(frag->size);
le->ctrl = ctrl;
le->opcode = OP_BUFFER | HW_OWNER;

re = tx_le_re(sky2, le);
re->skb = skb;
pci_unmap_addr_set(re, mapaddr, mapping);
pci_unmap_len_set(re, maplen, frag->size);
}

re->skb = skb;
le->ctrl |= EOP;

sky2->tx_prod = slot;
Expand All @@ -1720,23 +1732,9 @@ static int sky2_xmit_frame(struct sk_buff *skb, struct net_device *dev)

mapping_unwind:
for (i = sky2->tx_prod; i != slot; i = RING_NEXT(i, sky2->tx_ring_size)) {
le = sky2->tx_le + i;
re = sky2->tx_ring + i;

switch(le->opcode & ~HW_OWNER) {
case OP_LARGESEND:
case OP_PACKET:
pci_unmap_single(hw->pdev,
pci_unmap_addr(re, mapaddr),
pci_unmap_len(re, maplen),
PCI_DMA_TODEVICE);
break;
case OP_BUFFER:
pci_unmap_page(hw->pdev, pci_unmap_addr(re, mapaddr),
pci_unmap_len(re, maplen),
PCI_DMA_TODEVICE);
break;
}
sky2_tx_unmap(hw->pdev, re);
}

mapping_error:
Expand All @@ -1759,34 +1757,18 @@ static int sky2_xmit_frame(struct sk_buff *skb, struct net_device *dev)
static void sky2_tx_complete(struct sky2_port *sky2, u16 done)
{
struct net_device *dev = sky2->netdev;
struct pci_dev *pdev = sky2->hw->pdev;
unsigned idx;

BUG_ON(done >= sky2->tx_ring_size);

for (idx = sky2->tx_cons; idx != done;
idx = RING_NEXT(idx, sky2->tx_ring_size)) {
struct sky2_tx_le *le = sky2->tx_le + idx;
struct tx_ring_info *re = sky2->tx_ring + idx;
struct sk_buff *skb = re->skb;

switch(le->opcode & ~HW_OWNER) {
case OP_LARGESEND:
case OP_PACKET:
pci_unmap_single(pdev,
pci_unmap_addr(re, mapaddr),
pci_unmap_len(re, maplen),
PCI_DMA_TODEVICE);
break;
case OP_BUFFER:
pci_unmap_page(pdev, pci_unmap_addr(re, mapaddr),
pci_unmap_len(re, maplen),
PCI_DMA_TODEVICE);
break;
}

if (le->ctrl & EOP) {
struct sk_buff *skb = re->skb;
sky2_tx_unmap(sky2->hw->pdev, re);

if (skb) {
if (unlikely(netif_msg_tx_done(sky2)))
printk(KERN_DEBUG "%s: tx done %u\n",
dev->name, idx);
Expand Down
3 changes: 3 additions & 0 deletions drivers/net/sky2.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1984,6 +1984,9 @@ struct sky2_status_le {

struct tx_ring_info {
struct sk_buff *skb;
unsigned long flags;
#define TX_MAP_SINGLE 0x0001
#define TX_MAP_PAGE 000002
DECLARE_PCI_UNMAP_ADDR(mapaddr);
DECLARE_PCI_UNMAP_LEN(maplen);
};
Expand Down

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