We can increase the efficiency of rx path by using buffers to receive
packets then build SKBs around them just before passing into the network
stack. In contrast, preallocating SKBs too early reduces CPU cache
efficiency.
Check if we're in NAPI context when refilling RX. Normally we're almost
always running in NAPI context. Dispatch to napi_alloc_frag directly
instead of relying on netdev_alloc_frag which does the same but
with the overhead of local_bh_disable/enable.
Tested on BCM6328 320 MHz and iperf3 -M 512 to measure packet/sec
performance. Included netif_receive_skb_list and NET_IP_ALIGN
optimizations.
Before:
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 49.9 MBytes 41.9 Mbits/sec 197 sender
[ 4] 0.00-10.00 sec 49.3 MBytes 41.3 Mbits/secreceiver
After:
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-30.00 sec 171 MBytes 47.8 Mbits/sec 272 sender
[ 4] 0.00-30.00 sec 170 MBytes 47.6 Mbits/secreceiver
Signed-off-by: Sieng Piaw Liew
---
drivers/net/ethernet/broadcom/bcm63xx_enet.c | 111 ++-
drivers/net/ethernet/broadcom/bcm63xx_enet.h | 14 ++-
2 files changed, 71 insertions(+), 54 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bcm63xx_enet.c
b/drivers/net/ethernet/broadcom/bcm63xx_enet.c
index e34b05b10e43..c11491429ed2 100644
--- a/drivers/net/ethernet/broadcom/bcm63xx_enet.c
+++ b/drivers/net/ethernet/broadcom/bcm63xx_enet.c
@@ -220,7 +220,7 @@ static void bcm_enet_mdio_write_mii(struct net_device *dev,
int mii_id,
/*
* refill rx queue
*/
-static int bcm_enet_refill_rx(struct net_device *dev)
+static int bcm_enet_refill_rx(struct net_device *dev, bool napi_mode)
{
struct bcm_enet_priv *priv;
@@ -228,29 +228,29 @@ static int bcm_enet_refill_rx(struct net_device *dev)
while (priv->rx_desc_count < priv->rx_ring_size) {
struct bcm_enet_desc *desc;
- struct sk_buff *skb;
- dma_addr_t p;
int desc_idx;
u32 len_stat;
desc_idx = priv->rx_dirty_desc;
desc = &priv->rx_desc_cpu[desc_idx];
- if (!priv->rx_skb[desc_idx]) {
- if (priv->enet_is_sw)
- skb = netdev_alloc_skb_ip_align(dev,
priv->rx_skb_size);
+ if (!priv->rx_buf[desc_idx]) {
+ void *buf;
+
+ if (likely(napi_mode))
+ buf = napi_alloc_frag(priv->rx_frag_size);
else
- skb = netdev_alloc_skb(dev, priv->rx_skb_size);
- if (!skb)
+ buf = netdev_alloc_frag(priv->rx_frag_size);
+ if (unlikely(!buf))
break;
- priv->rx_skb[desc_idx] = skb;
- p = dma_map_single(&priv->pdev->dev, skb->data,
- priv->rx_skb_size,
- DMA_FROM_DEVICE);
- desc->address = p;
+ priv->rx_buf[desc_idx] = buf;
+ desc->address = dma_map_single(&priv->pdev->dev,
+ buf +
priv->rx_buf_offset,
+ priv->rx_buf_size,
+ DMA_FROM_DEVICE);
}
- len_stat = priv->rx_skb_size << DMADESC_LENGTH_SHIFT;
+ len_stat = priv->rx_buf_size << DMADESC_LENGTH_SHIFT;
len_stat |= DMADESC_OWNER_MASK;
if (priv->rx_dirty_desc == priv->rx_ring_size - 1) {
len_stat |= (DMADESC_WRAP_MASK >> priv->dma_desc_shift);
@@ -290,7 +290,7 @@ static void bcm_enet_refill_rx_timer(struct timer_list *t)
struct net_device *dev = priv->net_dev;
spin_lock(&priv->rx_lock);
- bcm_enet_refill_rx(dev);
+ bcm_enet_refill_rx(dev, false);
spin_unlock(&priv->rx_lock);
}
@@ -320,6 +320,7 @@ static int bcm_enet_receive_queue(struct net_device *dev,
int budget)
int desc_idx;
u32 len_stat;
unsigned int len;
+ void *buf;
desc_idx = priv->rx_curr_desc;
desc = &priv->rx_desc_cpu[desc_idx];
@@ -365,16 +366,14 @@ static int bcm_enet_receive_queue(struct net_device *dev,
int budget)
}
/* valid packet */
- skb = priv->rx_skb[desc_idx];
+ buf = priv->rx_buf[desc_idx];
len = (len_stat & DMADESC_LENGTH_MASK) >> DMADESC_LENGTH_SHIFT;
/* don't include FCS */
len -= 4;
if (len < copybreak) {
- struct sk_buff *nskb;
-
-
