[PATCH net-next v2 0/1] net: lantiq_xrx200: use skb cache

[PATCH net-next v2 0/1] net: lantiq_xrx200: use skb cache

[Aleksander Jan Bajkowski]

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.

Changelog:

  v2:
  - rebased patch to avoid conflicts

Aleksander Jan Bajkowski (1):
  net: lantiq_xrx200: use skb cache

 drivers/net/ethernet/lantiq_xrx200.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.30.2

[PATCH net-next v2 1/1] net: lantiq_xrx200: use skb cache

[Aleksander Jan Bajkowski]

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>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
---
 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 57f27cc7724e..13899720423f 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -239,7 +239,7 @@ 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);
 	if (!skb) {
 		skb_free_frag(buf);
 		net_dev->stats.rx_dropped++;
@@ -328,7 +328,7 @@ 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

Re: [PATCH net-next v2 1/1] net: lantiq_xrx200: use skb cache

[Jakub Kicinski]

On Sun, 28 Aug 2022 21:19:31 +0200 Aleksander Jan Bajkowski wrote:
> @@ -239,7 +239,7 @@ 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);

This gets called on MTU change, outside of softirq context, no?