From: Jerry Chu <redacted>
Date: Tue, 29 Oct 2013 19:13:50 -0700

On Tue, Oct 29, 2013 at 7:05 PM, Herbert Xu [off-list ref] wrote:

quoted

On Tue, Oct 29, 2013 at 10:02:53PM -0400, David Miller wrote:

quoted

From: Eric Dumazet <redacted>
Date: Tue, 29 Oct 2013 17:53:48 -0700

quoted

So should we apply the first fix to avoid the BUG_ON() ?

Please be more specific, are you talking about splitting up
this patch in some way?

I think Eric is referring to the patch that removes the BUG_ON
in skb_segment and deals with the new mega-GRO packets.

I think that's fine for stable, but for the long term we should
fix it properly as these new meag-GRO packets still retain the
existing packet boundaries and are trivially segmentable.

If we are indeed able to do that, I doubt we would even need
the sysctl patch since the GRO performance should be vastly
superior to the non-GRO case, even for a router/bridge.

Probably not the case for the simple forwarding case. See my
test result of some small (5-8%) CPU+throughput penalty from
GRO (over GRE tunnel) posted previously. But I can believe
the number may be very different if the forwarding path involves
more work (NAT, iptables filtering,...,etc) resulting in a higher per
pkt cost.

It's that way because it's not implemented properly.

GRO should always win, even on a router, because it decreases the
number of fundamental operations (routing lookups) that the stack
needs to perform.