diff options
| author | Lennert Buytenhek <buytenh@wantstofly.org> | 2009-05-06 03:01:22 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-05-06 15:33:39 -0700 |
| commit | 7fd96ce47ff83fc17ab78d465d8e067467a7f51e (patch) | |
| tree | 8267f14b3d6fe21feafe6b8dfd5768fc6010f32f | |
| parent | becfad979d1875aca15ef2a1eda68782e7ac7769 (diff) | |
mv643xx_eth: rework receive skb cache alignment
On the platforms that mv643xx_eth is used on, the manual skb->data
alignment logic in mv643xx_eth can be simplified, as the only case we
need to handle is where NET_SKB_PAD is not a multiple of the cache
line size. If this is the case, the extra padding we need can be
computed at compile time, while if NET_SKB_PAD _is_ a multiple of
the cache line size, the code can be optimised out entirely.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/mv643xx_eth.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c index cc16f3e4d89..05bb1c55da6 100644 --- a/drivers/net/mv643xx_eth.c +++ b/drivers/net/mv643xx_eth.c @@ -174,6 +174,7 @@ static char mv643xx_eth_driver_version[] = "1.4"; */ #define DEFAULT_RX_QUEUE_SIZE 128 #define DEFAULT_TX_QUEUE_SIZE 256 +#define SKB_DMA_REALIGN ((PAGE_SIZE - NET_SKB_PAD) % SMP_CACHE_BYTES) /* @@ -649,23 +650,20 @@ static int rxq_refill(struct rx_queue *rxq, int budget) refilled = 0; while (refilled < budget && rxq->rx_desc_count < rxq->rx_ring_size) { struct sk_buff *skb; - int unaligned; int rx; struct rx_desc *rx_desc; skb = __skb_dequeue(&mp->rx_recycle); if (skb == NULL) - skb = dev_alloc_skb(mp->skb_size + - dma_get_cache_alignment() - 1); + skb = dev_alloc_skb(mp->skb_size); if (skb == NULL) { mp->oom = 1; goto oom; } - unaligned = (u32)skb->data & (dma_get_cache_alignment() - 1); - if (unaligned) - skb_reserve(skb, dma_get_cache_alignment() - unaligned); + if (SKB_DMA_REALIGN) + skb_reserve(skb, SKB_DMA_REALIGN); refilled++; rxq->rx_desc_count++; @@ -964,8 +962,7 @@ static int txq_reclaim(struct tx_queue *txq, int budget, int force) if (skb != NULL) { if (skb_queue_len(&mp->rx_recycle) < mp->rx_ring_size && - skb_recycle_check(skb, mp->skb_size + - dma_get_cache_alignment() - 1)) + skb_recycle_check(skb, mp->skb_size)) __skb_queue_head(&mp->rx_recycle, skb); else dev_kfree_skb(skb); @@ -2336,6 +2333,14 @@ static void mv643xx_eth_recalc_skb_size(struct mv643xx_eth_private *mp) * size field are ignored by the hardware. */ mp->skb_size = (skb_size + 7) & ~7; + + /* + * If NET_SKB_PAD is smaller than a cache line, + * netdev_alloc_skb() will cause skb->data to be misaligned + * to a cache line boundary. If this is the case, include + * some extra space to allow re-aligning the data area. + */ + mp->skb_size += SKB_DMA_REALIGN; } static int mv643xx_eth_open(struct net_device *dev) |