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pasemi_mac: SKB unmap optimization 

pasemi_mac: SKB unmap optimization

Avoid touching skb_shinfo() in the unmap path, since it turns out to
normally cause cache misses and delays. instead, save number of fragments
in the TX_RING_INFO structures since that's all that's needed anyway.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This commit is contained in:
Olof Johansson 2007-11-28 20:57:45 -06:00 committed by David S. Miller
parent 28ae79f531
commit 7e9916e9dd
1 changed files with 26 additions and 15 deletions
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41
drivers/net/pasemi_mac.c
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@ -253,11 +253,11 @@ static int get_skb_hdr(struct sk_buff *skb, void **iphdr,
}
static int pasemi_mac_unmap_tx_skb(struct pasemi_mac *mac,
const int nfrags,
struct sk_buff *skb,
const dma_addr_t *dmas)
{
int f;
int nfrags = skb_shinfo(skb)->nr_frags;
struct pci_dev *pdev = mac->dma_pdev;
pci_unmap_single(pdev, dmas[0], skb_headlen(skb), PCI_DMA_TODEVICE);
@ -425,7 +425,7 @@ static void pasemi_mac_free_tx_resources(struct pasemi_mac *mac)
unsigned int i, j;
struct pasemi_mac_buffer *info;
dma_addr_t dmas[MAX_SKB_FRAGS+1];
int freed;
int freed, nfrags;
int start, limit;
start = txring->next_to_clean;
@ -438,10 +438,12 @@ static void pasemi_mac_free_tx_resources(struct pasemi_mac *mac)
for (i = start; i < limit; i += freed) {
info = &txring->ring_info[(i+1) & (TX_RING_SIZE-1)];
if (info->dma && info->skb) {
for (j = 0; j <= skb_shinfo(info->skb)->nr_frags; j++)
nfrags = skb_shinfo(info->skb)->nr_frags;
for (j = 0; j <= nfrags; j++)
dmas[j] = txring->ring_info[(i+1+j) &
(TX_RING_SIZE-1)].dma;
freed = pasemi_mac_unmap_tx_skb(mac, info->skb, dmas);
freed = pasemi_mac_unmap_tx_skb(mac, nfrags,
info->skb, dmas);
} else
freed = 2;
}
@ -749,6 +751,8 @@ static int pasemi_mac_clean_tx(struct pasemi_mac_txring *txring)
unsigned long flags;
struct sk_buff *skbs[TX_CLEAN_BATCHSIZE];
dma_addr_t dmas[TX_CLEAN_BATCHSIZE][MAX_SKB_FRAGS+1];
int nf[TX_CLEAN_BATCHSIZE];
int nr_frags;
total_count = 0;
batch_limit = TX_CLEAN_BATCHSIZE;
@ -758,6 +762,8 @@ static int pasemi_mac_clean_tx(struct pasemi_mac_txring *txring)
start = txring->next_to_clean;
ring_limit = txring->next_to_fill;
prefetch(&TX_DESC_INFO(txring, start+1).skb);
/* Compensate for when fill has wrapped but clean has not */
if (start > ring_limit)
ring_limit += TX_RING_SIZE;
@ -771,6 +777,9 @@ static int pasemi_mac_clean_tx(struct pasemi_mac_txring *txring)
u64 mactx = TX_DESC(txring, i);
struct sk_buff *skb;
skb = TX_DESC_INFO(txring, i+1).skb;
nr_frags = TX_DESC_INFO(txring, i).dma;
if ((mactx & XCT_MACTX_E) ||
(*chan->status & PAS_STATUS_ERROR))
pasemi_mac_tx_error(mac, mactx);
@ -779,21 +788,22 @@ static int pasemi_mac_clean_tx(struct pasemi_mac_txring *txring)
/* Not yet transmitted */
break;
skb = TX_DESC_INFO(txring, i+1).skb;
skbs[descr_count] = skb;
buf_count = 2 + skb_shinfo(skb)->nr_frags;
for (j = 0; j <= skb_shinfo(skb)->nr_frags; j++)
dmas[descr_count][j] = TX_DESC_INFO(txring, i+1+j).dma;
TX_DESC(txring, i) = 0;
TX_DESC(txring, i+1) = 0;
buf_count = 2 + nr_frags;
/* Since we always fill with an even number of entries, make
* sure we skip any unused one at the end as well.
*/
if (buf_count & 1)
buf_count++;
for (j = 0; j <= nr_frags; j++)
dmas[descr_count][j] = TX_DESC_INFO(txring, i+1+j).dma;
skbs[descr_count] = skb;
nf[descr_count] = nr_frags;
TX_DESC(txring, i) = 0;
TX_DESC(txring, i+1) = 0;
descr_count++;
}
txring->next_to_clean = i & (TX_RING_SIZE-1);
@ -802,7 +812,7 @@ static int pasemi_mac_clean_tx(struct pasemi_mac_txring *txring)
netif_wake_queue(mac->netdev);
for (i = 0; i < descr_count; i++)
pasemi_mac_unmap_tx_skb(mac, skbs[i], dmas[i]);
pasemi_mac_unmap_tx_skb(mac, nf[i], skbs[i], dmas[i]);
total_count += descr_count;
@ -1299,6 +1309,7 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev)
}
TX_DESC(txring, fill) = mactx;
TX_DESC_INFO(txring, fill).dma = nfrags;
fill++;
TX_DESC_INFO(txring, fill).skb = skb;
for (i = 0; i <= nfrags; i++) {