[PATCH net-next] net: lantiq_xrx200: use skb cache

Aleksander Jan Bajkowski
2022-07-12T18:15:19Z

napi_build_skb() reuses NAPI skbuff_head cache in order to save some
cycles on freeing/allocating skbuff_heads on every new Rx or completed
Tx.
Use napi_consume_skb() to feed the cache with skbuff_heads of completed
Tx. The budget parameter is added to indicate NAPI context, as a value
of zero can be passed in the case of netpoll.

NAT performance results on BT Home Hub 5A (kernel 5.15.45, mtu 1500):

Fast path (Software Flow Offload):
Up Down
Before 702.4 719.3
After 707.3 739.9

Slow path:
Up Down
Before 91.8 184.1
After 92.0 185.7

Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
---
drivers/net/ethernet/lantiq_xrx200.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c
index 5edb68a8aab1..83e07404803f 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -238,7 +238,7 @@ static int xrx200_hw_receive(struct xrx200_chan *ch)
return ret;
}

- skb = build_skb(buf, priv->rx_skb_size);
+ skb = napi_build_skb(buf, priv->rx_skb_size);
skb_reserve(skb, NET_SKB_PAD);
skb_put(skb, len);

@@ -321,7 +321,7 @@ static int xrx200_tx_housekeeping(struct napi_struct *napi, int budget)
pkts++;
bytes += skb->len;
ch->skb[ch->tx_free] = NULL;
- consume_skb(skb);
+ napi_consume_skb(skb, budget);
memset(&ch->dma.desc_base[ch->tx_free], 0,
sizeof(struct ltq_dma_desc));
ch->tx_free++;
--
2.30.2