netdev - Re: [PATCH net-next] r8169: use netif_receive_skb

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Message-ID: <20190401145326.0196c746@carbon>
Date:   Mon, 1 Apr 2019 14:53:26 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     David Miller <davem@...emloft.net>, hkallweit1@...il.com,
        nic_swsd@...ltek.com, netdev@...r.kernel.org, ecree@...arflare.com,
        brouer@...hat.com
Subject: Re: [PATCH net-next] r8169: use netif_receive_skb_list batching

On Mon, 1 Apr 2019 02:17:12 -0700
Eric Dumazet <eric.dumazet@...il.com> wrote:

> On 03/31/2019 11:11 AM, David Miller wrote:
> > From: Heiner Kallweit <hkallweit1@...il.com>
> > Date: Sun, 31 Mar 2019 15:18:48 +0200
> >   
> >> Use netif_receive_skb_list() instead of napi_gro_receive() to benefit
> >> from batched skb processing.
> >>
> >> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>  
> > 
> > Applied.
> >   
> 
> This means no GRO at all, and reduced performance in many useful
> cases.

As Eric says, this in-effect disables GRO for this driver.  This will
very likely give a slowdown for local TCP delivery (while it might
helps for UDP and forwarding). 

That is why I was saying we need a GRO version of this...
(which need to be combined with bulk SKB alloc, to compete with GRO
fast-recycle of same SKB).

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer