netdev - Re: [PATCH] bgmac: Remove all offloading features, including GRO.

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Date:   Fri, 15 Sep 2017 17:34:56 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Rosen Penev <rosenp@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH] bgmac: Remove all offloading features, including GRO.

On Fri, 2017-09-15 at 17:23 -0700, Rosen Penev wrote:
> On a linksys E1200v1 (actually a crossflashed E1000v2), the offloading features give no measurable benefit to speed or latency. Furthermore, disabling GRO actually improves iperf performance by a whoppimg 3mbps. Results:
> 
> Currently:

> 
> v2: Changed napi_gro_receive to netif_receive_skb. Seems to have an identical result.
> 
> Signed-off-by: Rosen Penev <rosenp@...il.com>
> ---
>  drivers/net/ethernet/broadcom/bgmac.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c
> index 48d672b204a4..1fb0053aeee7 100644
> --- a/drivers/net/ethernet/broadcom/bgmac.c
> +++ b/drivers/net/ethernet/broadcom/bgmac.c
> @@ -483,7 +483,7 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
>  			skb->protocol = eth_type_trans(skb, bgmac->net_dev);
>  			bgmac->net_dev->stats.rx_bytes += len;
>  			bgmac->net_dev->stats.rx_packets++;
> -			napi_gro_receive(&bgmac->napi, skb);
> +			netif_receive_skb(skb);
>  			handled++;
>  		} while (0);
>  

And have you tested 1Gbit link speed ?
( Or 2.5 Gbit link speed )

If you want to disable GRO on your host, fine : you can use ethtool -K