netdev - Re: No GSOs to i40e with VXLAN

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Date:	Fri, 13 Jun 2014 21:38:55 -0700 (PDT)
From:	Joseph Gasparakis <joseph.gasparakis@...el.com>
To:	Tom Herbert <therbert@...gle.com>
cc:	Joseph Gasparakis <joseph.gasparakis@...el.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
Subject: Re: No GSOs to i40e with VXLAN

On Fri, 13 Jun 2014, Tom Herbert wrote:

> On Fri, Jun 13, 2014 at 5:15 PM, Joseph Gasparakis
> <joseph.gasparakis@...el.com> wrote:
> > Hi all,
> >
> > I quickly tested VXLAN on i40e with net-next with commit id
> > f9da455b93f6ba076935b4ef4589f61e529ae046 and the i40e driver has stopped
> > receiving GSOs even when advertising tx-udp_tnl-segmentation which means
> > our VXLAN segmentation offload. I am guessing this has something to do
> > with Tom's recent UDP work but this is just a guess as unfortunatly I
> > do not have the time to debug this, but I am signing up to review and test
> > patches fixing this issue.
> >
> I verified tunnel offload works properly with bnx2x (I'm using simple
> vxlan interfaces not OVS).
> 

Ok, I will try to have a quick look at bnx2x and i40e and see the 
differences in what the two drivers advertise in terms of netdev features and 
hw_enc_features.

> One possibility I can think of is that UDP checksums are somehow
> enabled. If you're using IPv6 this probably the case (but I assume
> you're seeing this with IPv4). If checksums are inadvertently enabled
> somehow in IPv4 this should should up in tcpdump on the Ethernet
> interface.

Let me explain a bit my setup:

I am using two linux boxes back to back, on my DUT I have an i40e and I 
am bringing a vxlan interface in both machines. No bridge, no VMs, no OVS.

I am using some simple perl scripts using TCP sockets to send a number of 
bytes from DUT to my link partner and even if I send 50k in one message I 
don't see any GSOs. Instead I get many non-GSO skbs leading me to the 
conclusion that the stack must have segmented the skb before passing it on 
to the driver. I am also using netperf with TCP_STREAM and I don't see any 
GSOs either. All the above done using IPv4 only. And if I do the same on 
the i40e interface instead of vxlan I do see GSOs again.

Both these tests would result to the stack sending GSOs last time I did a 
smoke test on vxlan and i40e (about 3 weeks ago or so...).  

The checksum offloads seem to be working as before however.

Thanks

Joseph

> 
> Thanks,
> Tom
> 
> > The driver still gets GSOs with non VXLAN traffic (tested with TCP).
> >
> > Thanks
> >
> > Joseph
> 
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