On Thu, Sep 27, 2012 at 5:48 AM, Eric Dumazet [off-list ref] wrote:

From: Eric Dumazet <edumazet@google.com>

Add GRO capability to IPv4 GRE tunnels, using the gro_cells
infrastructure.

Tested using IPv4 and IPv6 TCP traffic inside this tunnel, and
checking GRO is building large packets.

Signed-off-by: Eric Dumazet <edumazet@google.com>

When I was thinking about doing this, my original plan was to handle
GRO/GSO by extending the current handlers to be able to look inside
GRE and then loop around to process the inner packet (similar to what
is done today with skb_flow_dissect() for RPS).  Is there a reason to
do it in the device?

Pushing it earlier/later in the stack obviously increases the benefit
and it will also be more compatible with the forthcoming OVS tunneling
hooks, which will be flow based and therefore won't have a device.

Also, the next generation of NICs will support this type of thing in
hardware so putting the software versions very close to the NIC will
give us a more similar abstraction.