On Fri, Dec 04, 2020 at 10:50:45AM +0100, Eric Dumazet wrote: > > > On 12/4/20 6:46 AM, Sieng Piaw Liew wrote: > > Use netif_receive_skb_list to batch process rx skb. > > Tested on BCM6328 320 MHz using iperf3 -M 512, increasing performance > > by 12.5%. > > > > > > Well, the real question is why you do not simply use GRO, > to get 100% performance gain or more for TCP flows. > > > netif_receive_skb_list() is no longer needed, > GRO layer already uses batching for non TCP packets. > > We probably should mark is deprecated. > > diff --git a/drivers/net/ethernet/broadcom/bcm63xx_enet.c > b/drivers/net/ethernet/broadcom/bcm63xx_enet.c > index > 916824cca3fda194c42fefec7f514ced1a060043..6fdbe231b7c1b27f523889bda8a20ab7eaab65a6 > 100644 > --- a/drivers/net/ethernet/broadcom/bcm63xx_enet.c > +++ b/drivers/net/ethernet/broadcom/bcm63xx_enet.c > @@ -391,7 +391,7 @@ static int bcm_enet_receive_queue(struct net_device *dev, > int budget) > skb->protocol = eth_type_trans(skb, dev); > dev->stats.rx_packets++; > dev->stats.rx_bytes += len; > - netif_receive_skb(skb); > + napi_gro_receive_skb(&priv->napi, skb); > > } while (--budget > 0); >
The bcm63xx router SoC does not have enough CPU power nor hardware accelerator to process checksum validation fast enough for GRO/GSO. I have tested napi_gro_receive() on LAN-WAN setup. The resulting bandwidth dropped from 95Mbps wire speed down to 80Mbps. And it's inconsistent, with spikes and drops of >5Mbps. The ag71xx driver for ath79 router SoC reverted its use for the same reason. http://lists.infradead.org/pipermail/lede-commits/2017-October/004864.html
