netdev - Re: [net-next PATCH] net: ipv4: fix listify ip_rcv

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Date:   Wed, 11 Jul 2018 22:06:49 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Saeed Mahameed <saeedm@...lanox.com>
Cc:     Edward Cree <ecree@...arflare.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        brouer@...hat.com
Subject: Re: [net-next PATCH] net: ipv4: fix listify ip_rcv_finish in case
 of forwarding

On Wed, 11 Jul 2018 19:05:20 +0000
Saeed Mahameed <saeedm@...lanox.com> wrote:

> On Wed, 2018-07-11 at 17:01 +0200, Jesper Dangaard Brouer wrote:
> > Only driver sfc actually uses this, but I don't have this NIC, so I
> > tested this on mlx5, with my own changes to make it use
> > netif_receive_skb_list(),
> > but I'm not ready to upstream the mlx5 driver change yet.  
> 
> 
> Thanks Jesper for sharing this, should we look forward to those patches
> or do you want us to implement them ?

Well, I would prefer you to implement those.  I just did a quick
implementation (its trivially easy) so I have something to benchmark
with.  The performance boost is quite impressive!

One reason I didn't "just" send a patch, is that Edward so-fare only
implemented netif_receive_skb_list() and not napi_gro_receive_list().
And your driver uses napi_gro_receive().  This sort-of disables GRO for
your driver, which is not a choice I can make.  Interestingly I get
around the same netperf TCP_STREAM performance.  I assume we can get
even better perf if we "listify" napi_gro_receive.

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