netdev - Re: LRO/GRO and libpcap packet reordering

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Date:	Fri, 15 Mar 2013 00:21:29 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Ben Hutchings <bhutchings@...arflare.com>,
	Network Development <netdev@...r.kernel.org>
Subject: Re: LRO/GRO and libpcap packet reordering

On Fri, 2013-03-15 at 00:16 +0100, Eric Dumazet wrote:
> On Thu, 2013-03-14 at 15:58 -0700, Andy Lutomirski wrote:
> 
> > Right.  This is the part that I'm wondering about an efficient fix to
> > (i.e. flush GRO state for one flow whenever a packet for the reversed
> > flow is seen).
> 
> It doesnt seem doable easily, because network header and tcp headers are
> handled in two separate functions in GRO stack (inet_gro_receive() &
> tcp_gro_receive()
> 
> What you could do is changing MAX_GRO_SKBS from 8 to 1
> (basically allowing only one flow in GRO stack)
> 
> 
Well, its not enough, some changes would be needed to force a flush each
time a new flow is detected.



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