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

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Message-ID: <207c232c-1ade-ff54-4384-76f4d0280a7d@gmail.com>
Date:   Mon, 1 Apr 2019 19:39:06 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Edward Cree <ecree@...arflare.com>,
        David Miller <davem@...emloft.net>, eric.dumazet@...il.com
Cc:     nic_swsd@...ltek.com, netdev@...r.kernel.org, brouer@...hat.com
Subject: Re: [PATCH net-next] r8169: use netif_receive_skb_list batching

On 01.04.2019 19:31, Edward Cree wrote:
> On 01/04/2019 18:14, David Miller wrote:
>> From: Eric Dumazet <eric.dumazet@...il.com>
>> Date: Mon, 1 Apr 2019 02:17:12 -0700
>>
>>> This means no GRO at all
>> I do not think that is true as the SKB list layer does queue up to
>> GRO.
> No, Eric is right; the current list layer bypasses GRO completely.
> 
> netif_receive_skb_list() ends up doing the same things netif_receive_skb()
> would do on each SKB in the list, and that does not include GRO.
> (For this reason the sfc driver only uses netif_receive_skb_list() for
> non-TCP packets; TCP packets go to napi_gro_frags().)
> I had a patch series to add napi_gro_receive_list() which would use the
> SKB list layer to handle the packets GRO didn't coalesce ([1]) but the
> performance tests I ran were inconclusive and it never got applied.
> 
> -Ed
> 
> [1]: https://marc.info/?l=linux-netdev&m=154221888012410&w=2
> 
Patch 0a25d92c6f4f ("dpaa2-eth: use netif_receive_skb_list") was well
perceived [1], therefore I was under the assumption that
netif_receive_skb_list is kind of successor for napi_gro_receive().
Does what you say apply to that patch too?

Based on feedback so far it seems to best if I revert the patch.

Heiner

[1] https://patchwork.ozlabs.org/patch/1064334/