netdev - Re: Kernel memory leak in bnx2x driver with vxlan tunnel

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Date:	Thu, 21 Jan 2016 03:27:34 +0100
From:	Thomas Graf <tgraf@...g.ch>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Jesse Gross <jesse@...nel.org>, John <john.phillips5@....com>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Tom Herbert <tom@...bertland.com>, david.roth@....com,
	Pravin B Shelar <pshelar@...ira.com>
Subject: Re: Kernel memory leak in bnx2x driver with vxlan tunnel

On 01/20/16 at 04:34pm, Eric Dumazet wrote:
> On Wed, 2016-01-20 at 16:19 -0800, Jesse Gross wrote:
> 
> > I have a patch that implements the comparison between dsts. For
> > packets without a dst, there isn't really a cost and if we do have a
> > dst then GRO is still a benefit. So it seems like it is worth doing,
> > even if it is more expensive than is ideal.
> 
> You guys really want to kill GRO performance.
> 
> Really the aggregation should happen at the first layer (ethernet
> device), instead of doing it after tunnel decap.
> 
> This is already done for GRE, IPIP, SIT, ...
> 
> GRO having to access metadata looks wrong, if you think about trying to
> do the same function in hardware (offload)

If I understand Jesse correctly then the added cost is only for
metadata enabled packets. Though I agree, what's the benefit of
doing GRO after decap?

It seems like it's way too late and we've already paid the cost
by going through the stack for each outer header packet.