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

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Date:   Fri, 15 Sep 2017 23:04:29 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     rosenp@...il.com, Eric Dumazet <eric.dumazet@...il.com>
CC:     netdev@...r.kernel.org
Subject: Re: [PATCH] bgmac: Remove all offloading features, including GRO.

On September 15, 2017 5:38:42 PM PDT, rosenp@...il.com wrote:
>I have not. Unfortunately I own no gigabit hardware to test this on.
>The MIPS CPU runs at 300MHz on my unit.
>

bgmac is used on Gigabit capable hardware, like Northstar and Northstar Plus, and others too, so unless you can get access to such HW or get confirmation from someone that your patches changes something, I would just drop this change and not bother. This is already not 100mbits/sec linerate...

>On Fri, 2017-09-15 at 17:34 -0700, Eric Dumazet wrote:
>> 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
>> 
>> 
>> 

(please don't top-post)
-- 
Florian