Subject: Re: linux-3.0.18+r8169+ipv4/tcp forwarding = tso/gso weirdness and performance degration

From: Timo Teras <[email-masked]>
Date: Wed, 14 Mar 2012 21:51:42 +0200

On Wed, 14 Mar 2012 19:29:14 +0000 Ben Hutchings
<[email-masked]> wrote:

> On Wed, 2012-03-14 at 19:29 +0200, Timo Teras wrote:
> [...]
> > gro off. I am even trying now with:
> > 
> > Offload parameters for eth2:
> > rx-checksumming: off
> > tx-checksumming: off
> > scatter-gather: off
> > tcp segmentation offload: off
> > udp fragmentation offload: off
> > generic segmentation offload: off
> [...]
> 
> GRO isn't even reported there!  Apparently you need a newer version of
> ethtool.

Very good point. I thought gso also enabled gro, but seems that my
ethtool was old.

And GRO was enabled along with some other stuff. Turning GRO off made
my tcp performance immediately a lot better; jumped from 2MB/s to 8MB/s
or so (not ideal yet, though; but the remainder of the difference could
be related to other issue).

So something is definitely broke in 3.0.x with GRO enabled, but GSO off.